Connector Assembly for Film Circuitry

The invention relates to film circuit connectors and to components thereof, in particular, to film circuitry, for circuit board applications.

The increasing miniaturization of electrical devices together with the often conflicting requirements for high volume, mass production at low manufacturing and applied cost but with zero defect, place exacting demands on connectors and associated circuitry.

Attempts to satisfy such requirements are described in the above-mentioned parent application as well as in Japanese patent publication number 3-112082 published May, 1991 in which the receptacle connector 310 of a film connector comprises a housing 311 molded in one piece of insulating plastic material with a plug receiving cavity 311a opening to a mating face 311b, film circuit supporting members 312 and 313 respectively, in each of which flexible film circuits 314 and 315, respectively, are insert molded to form integral bodies retained inserted in the housing 311 by an elongate T-section base member 317. Prior to insertion, a pair of identical helical coil springs 316 are mounted in longitudinally members 312, 313 behind film circuit contact areas 314a and 315a biassing then to protrude into the cavity 311a.

The plug connector 320 comprises a housing 321 having a receptacle connector receiving cavity 312a, first and second film circuit supporting and locating members 322 and 323, respectively, first and second film or sheet-form flexible circuits or boards 324 and 325, respectively, in-molded in respective film circuit supporting members to form integral bodies which are inserted in the housing and retained by a base member 327 of generally T-shaped cross-section. Film circuit contact areas 324a and 325a remain exposed during the in-molding process and are pressed into engagement with contact areas 314a and 314b, respectively, on mating the plug and receptacle connectors with resilient depression of the springs 316. Connection to respective circuit boards 301 ad 302 is effected with training portions of the film circuit which extend out of the respective housings adjacent the circuit boards by a reflow soldering technique.

A disadvantage of such approach is that the counter-force to the spring contact force acts directly on the plastic walls 311 of the receptacle housing tending to distort or distend the walls by bending with a risk of breakage and decrease or loss of contact force. Clearly, increasing the contact force to assure more reliable electrical connection increases the stress on the housing while any distortion of the housing walls, which may be progressive over time, e.g. creep, will reduce the contact force and reduce reliability.

Similar problems may arise with another prior receptacle connector described in Japanese patent publication number and acknowledged as prior art in the parent application with reference to FIGS. 21 and 22 thereof, in which film circuits have leading ends secured around a cylindrical body of metal loaded elastomer located in a housing compartment adjacent the mating face and providing the contact force.

In a different approach, disclosed in Japanese Patent Publication 40-2588 and U.S. Pat. No. 3,154,356 to Crimmins, issued Oct. 27, 1964, reliance for contact pressure between engaging film circuits of matable parts and receptacle connectors is placed on inwardly projecting, curved, protuberances on end portions of walls of a spring which has been bent into channel or U-section within which the film circuit extends in slack condition. The spring is formed by bending a metal plate resulting in risk of an unevenness of the curvature of the protuberance along the length of the spring which may also be subject to relaxation while, the slack condition of the film circuit increases risk of shift and contact misalignment, particularly with conductive tracks at desirably small pitches. In addition, in that construction, the channel walls should be relatively long (high, increasing the size of the connector structure undesirably).

There is clearly a risk that an uneven spring contact force will result in faulty connection to some circuit paths.

Further problems may arise in using conventional film circuitry both on mating, when frictional engagement or butting together of the conductive tracks of the film circuit possibly causes peeling or abrasion thereof, or inadvertent cross connection at the surface of the circuit board arising from using the reflow solder process with conductors at very close pitch.

Other problems arise in securely anchoring the connectors to the circuit board with increased risk of accidental abutment or strain as a result of the high density of components on the circuit board and the consequently increased desirability of at least some degree of effective electrical shielding while occupying a minimum of circuit board area.

It is one object of the invention to obviate or ameliorate the above-mentioned disadvantages in eliminating both the reactive contact spring force acting on the housing wall and ensuring substantially uniform contact force along the length of the spring to respective conductive tracks of the film circuit.

It is a further object of the invention to obviate the problem of cross-connection or short circuiting between the individual conductive tracks by retaining the film circuit in the channel section spring precisely located and in taut condition both after assembly and at an early stage during assembly and maintaining the precise positions throughout the assembly process obviating any requirement for adjustment of the film circuit position at a later stage which would involve difficult and time consuming manipulation.

A further object of the invention is to utilize a channel spring construction to establish contact force while enabling the connector to be of acceptably low height and size while avoiding irregularity in contact force.

It is also desirable to provide a film circuit adapted to minimize problems of cross connection both with the connector and to the circuit board.

Further objects of the invention are to provide connectors which are economic to manufacture and mount on the circuit board using mass production techniques.

According to one aspect of the invention there is provided a connector assembly for film circuitry comprising matable plug and receptacle connector members, the receptacle member including an insulating housing having a mating face and providing a plug receiving cavity opening to the mating face; a channel section spring member having a base and side walls upstanding from opposite sides of the base, film circuit pressing protuberances on opposite side walls at locations remote from the base and extending inwardly of the channel, providing a channel mouth, the receptacle spring being mounted in the housing with the channel mouth opening towards the mating face; a film circuit mounted in the housing in taut condition and having a medial portion inserted in the channel and mating contact areas extending over the protuberances away from the mating face and opposite end portions extending out of the channel over respective channel side walls; the plug connector comprising a plug housing having a mating face and a plug-like film circuit supporting member; and, a film circuit supported on the film circuit supporting member and having mating contact areas extending away from the mating face in taut condition, at least one resiliently compressible spring means extending longitudinally of the film circuit supporting member behind the mating contact areas of the film circuit at locations aligned with the protruberances, in a fully mated condition of the connector whereby, on mating the plug and receptacle members, the film circuit supporting member carrying the film circuit is received in the channel mouth between the protuberances flexing resiliently the side walls apart so that the protuberances and the compressible spring press between them corresponding contact areas of the two film circuits together into engagement to effect permanent electrical connection between respective conductive tracks thereof.

Contact force variations arising from imperfections in forming or subsequent relaxation of the receptacle spring will be accommodated by the resilient compression of the opposed plug spring located behind the film circuit contact area ensuring a substantially predetermined and constant contact force between all circuits.

The compressible plug spring may be formed by an endless, possibly elastomeric band, encircling the film circuit supporting member and may suitably be retained in a groove formed therein or may be constituted by separate strips located on respective opposite sides of the film supporting member.

The receptacle spring may suitably be stamped and formed from sheet metal stock and anchoring tab portions may be struck from respective opposite sides thereof at locations adjacent the base to extend downwardly therefrom and have laterally extending circuit board connecting and anchoring portions to effect both mechanical anchoring to the circuit board and electrical connection thereto so that the receptacle spring member may act as a shield.

Means may be provided on the receptacle housing to maintain the side walls of the receptacle spring resiliently flexed apart in prestressed condition.

Such arrangement may both advantageously reduce the amount of flexure required of the receptacle spring to produce a satisfactory contact force on insertion of the plug member therein thereby in practice reducing the insertion force and frictional effects caused by mating, further reducing the insertion force and abrasive wear of the contact areas.

The prestressing means may conveniently progressively urge the receptacle spring side walls apart during assembly thereof into the housing.

According to another aspect of the invention there is provided a connector assembly as described above in which the receptacle housing cavity has opposite, elongate side walls and opposite end walls extending away from the mating face and defining an aperture remote from the mating face, an elongate film circuit locating rib of greater lateral width than the mouth of the receptacle spring extending along the housing, medially of the aperture, an elongate spring mounting member of rigid insulating material having receptacle spring locating means and film circuit locating portions at opposite sides thereof, the film circuit being receivable in the housing with the medial portion thereof located under the film circuit locating rib and the contact areas extending through the aperture on respective opposite lateral sides of the film circuit locating rib into the cavity towards the mating face and end portions folded back away from the mating face and returned through the aperture on respective opposite lateral sides of the rib, the spring mounting member being insertible into the aperture with the spring base located on the spring locating means by flexure apart of the channel walls riding over the film circuit locating rib with the channel side wall portions and protruberences received in respective folds formed in the film circuit on opposite sides of the medial portion and with the medial portions of the film trapped between the rib and the base of the receptacle spring, the film circuit locating portions engaging trailing end portions of the film circuit trapping them against the respective opposite side walls of the housing and extending out of the housing exposed for connection to a circuit board and with contact areas of the film circuit located by the respective spring protruberences extending inwardly on respective opposite sides of the channel adjacent the mating face, cooperable means being provided for securing the channel spring mounting member to the housing.

This may ensure accurate location of the film circuit is maintained at all stages of assembly with the housing and subsequently during and after mating with the plug connector. Upward and lateral movement of the film circuit is limited so that accurate connection of corresponding tracks of the mating film circuits can be established, in other words.

In one embodiment, the receptacle housing has means engagable with the spring for urging the side walls apart into prestressed condition, preferably, progressively, by insertion of the spring into the housing.

This reduces spring movement and insertion forces, particularly frictional, during mating and decreases risks of misalignment and consequential damage in view of the wider spring mouth in the preloaded condition.

According to another aspect of the invention, the film circuit comprises a series of conductive tracks extending across a web of insulating material away from the medial portion and having a row of mating contact portions in the contact areas exposed to the front mating contact face joined by respective linking portions insulated from the contact face, preferably by location on the rear face of the web, to respective board connecting portions exposed to a rear face for connection to a circuit board.

The isolation of the linking portions of the conductive tracks from the front, mating contact face obviates risk of wear or peeling of the conductors otherwise possibly arising as a result of the high frictional force produced on mating. In addition, since the linking conductors are concealed on the rear surface of the film, there is no risk of shorting between the individual linking conductors otherwise possibly arising if metal granules or metal powder is accidentally accumulated on the front surface of the film member trapped in the receptacle spring.

An insulating coating may advantageously also be place on the linking portions to cover the exposed rear surfaces thereof where the receptacle spring member is of metal.

Specific embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

FIG. 1 is a perspective view, partly in cross section of a first example of receptacle connector according to the invention;

FIGS. 2(a), 2(b) and 2(c) are top plan, side elevation, partly in cross section, and end elevational views of the receptacle connector of claim 1;

FIG. 3 is an underplan view of the first example;

FIGS. 4(a) and 4(b) are, respectively, end elevational and perspective views, partly in cross-section, of a channel-section receptacle spring of the first example of receptacle connector;

FIG. 5 is a plan view of a precursor of a film circuit of the first example of receptacle connector;

FIGS. 6(a) and 6(b) are, respectively, cross-sectional views taken along lines 6(a) and 6(b) of FIG. 2(a);

FIG. 6(c) is a fragmentary cross-sectional view taken along line 6c-6c of FIG. 6(b);

FIG. 7 is a fragmentary perspective view of the first example of receptacle connector;

FIGS. 8(a), 8(b) and 8(c) are cross-sectional views taken, respectively, along lines corresponding to 6b--6b of FIG. 2(a) showing the components of the first example of receptacle connector at progressive stages of assembly;

FIG. 9(a) is a perspective view, partly in cross-section, of a first embodiment of plug connector according to the invention;

FIG. 9(b) is a perspective view of an anchoring element for the plug connector of FIG. 9(a);

FIGS. 10(a), 10(b) and 10(c) are, respectively, plan, side elevational partly in cross-section, and end elevational views of the plug connector of FIG. 9(a);

FIG. 11 is an underplan view of the plug connector of FIG. 9(a);

FIG. 12 is a fragmentary, cross-sectional view taken in a horizontal plane extending through the film circuit supporting member of the connector of FIG. 9(a);

FIGS. 13(a) and 13(b) are, respectively, cross-sectional views taken along lines 13a and 13b of FIG. 10(a);

FIG. 14 is a cross-sectional view of the connector assembly with the plug and receptacle connectors in fully mated condition;

FIG. 15 is a fragmentory perspective view of a second embodiment of plug connector according to the invention;

FIGS. 16(a) and 16(b) are end elevational and fragmentary side elevational views of the second embodiment of plug connector shown in FIG. 15;

FIG. 17 is a cross-sectional view of the second embodiment of plug connector in fully mated condition with the first embodiment of receptacle connector;

FIG. 18 is a cross-sectional view of further embodiments of plug and receptacle connectors aligned for mating;

FIG. 19 is a plan view of a precursor flexible circuit for use in the connectors of FIG. 18;

FIG. 20 is a cross-sectional view of plug and receptacle connectors described in the parent application;

FIG. 21 is a perspective view, partly in cross section, of another embodiment of receptacle connector incorporating modified film circuitry;

FIGS. 22(a) and 22(b) are front, plan and rear, underplan views of mating contact and rear faces of a modified film circuit for use in the connector;

FIG. 23 is a fragmentary cross-sectional view of the modified film circuitry;

FIG. 24(a) is a perspective view, partly in cross-section of a further embodiment of receptacle connector incorporating film circuitry modified in a fashion complementary to that of FIG. 21;

FIG. 24(b) is a perspective view of an anchoring element for the plug connector of FIG. 24(a).

FIG. 25 is a schematic cross-sectional and end elevational view of connector assemblies according to FIG. 16(a), linked together daisy-chain fashion;

FIGS. 26 and 27 are a plan of front, mating contact face and an underplan view of the rear face of film circuits incorporated in the connector assembly of FIG. 25;

FIGS. 28 and 29 are plan views of the front, mating contact faces and the rear faces of a film circuit incorporated in the embodiment of FIG. 18;

FIG. 30 is a fragmentary plan view of a prior film circuit.

FIG. 31 is a perspective view, partly in cross-section of a further embodiment of receptacle connector according to the invention.;

FIG. 32 is a fragmentary perspective view of the receptacle connector shown in FIG. 31 and with a housing member removed;

FIG. 33 is a fragmentary perspective view of the receptacle connector of FIG. 32 at an enlarged scale;

FIGS. 34(a)-34(f) are, respective, plan, side elevational partly in cross-section, underplan, end elevational, and cross-sectional views along lines 34e--34e and 34f--34f of FIG. 34a showing a housing member of the receptacle connector of FIG. 31;

FIGS. 35(a) and 35(b) are plan and elevational views of a fastening element of the receptacle connector of FIG. 31;

FIGS. 36(a)-36(e) are plan, side elevational, underplan, opposite side elevational and cross-sectional views, the last being taken along line 36e--36e of FIG. 36(b), of a film positioning and clamping member, of the receptacle connector of FIG. 31;

FIGS. 37(a)-37(d) are, respectively, plan, elevational, underplan and cross-sectional view of a base member of the receptacle connector of FIG. 1, the last view being taken along lines 37d--37d of FIG. 37(a);

FIGS. 38(a) and 38(b) are side elevational and end elevational views of a spring of the receptacle connector of FIG. 1;

FIGS. 38(c)-38(g) are cross-sectional views taken, respectively, along lines 38(c)-38(g) of FIG. 38(a);

FIGS. 39(a)-39(e) are, respectively, side elevational partly in cross-section, underplan, end elevational and cross-sectional views of a housing cover member of the receptacle connector of FIG. 1, the cross-section being taken along line 39e--39e on FIG. 39(a);

FIGS. 40(a) and 40(b) are plan and underplan views showing the front, mating and rear faces, respectively, of a film circuit of the receptacle connector of FIG. 31;

FIG. 41 is a perspective view, partly in cross-section of a plug connector for mating with the receptacle connector of FIG. 31;

FIGS. 42(a)-42(e) are, respectively, plan, side elevational partly in cross-section, underplan, end elevational and cross-sectional views of an outer housing of the plug connector of FIG. 41, the cross-section being taken along line 42e--42e of FIG. 42(a);

FIGS. 43(a)-43(e) are, respectively, plan, side elevational, underplan, end elevational and cross-sectional views of a film circuit supporting member of the plug connector of FIG. 41, the cross-section being taken along lines 43e--43e of FIG. 43(a);

FIGS. 44(a) and 44(b) are, respectively, plan and underplan views of a film circuit to the plug connector shown in FIG. 41.

FIG. 45 is a cross-sectional view showing the plug and receptacle connectors of FIGS. 31 and 41 aligned for mating; and

FIG. 46 is a cross-sectional view of the plug and socket connectors fully mated and

FIGS. 47a and 47b are cross-sectional views in orthogonal planes of an apertured film circuit shown in FIG. 23 of the parent application, U.S. Pat. No. 5,156,533, aligned for connection to a circuit board by a reflow solder technique; and FIGS. 47c and 47d are, respectively, similar views after connection to the circuit board.

As shown in FIGS. 1-8, the receptacle connector comprises a housing 10, a receptacle spring mounting member 20, a film circuit 30 and a channel-section receptacle spring 40.

The receptacle connector 10 comprises a rectanguloid housing 11 molded in one piece of insulating plastic material and having opposite elongate side walls 11a and 11b and end walls 11c and 11d, respectively, which extend away from a slotted plug connector receiving mating face 12a and define a plug receiving cavity 12 open to a board engaging face, remote from the mating face. An elongate film circuit supporting rib 11e extends medially of the board engaging face between opposite end walls. A series of locating and retention pin receiving apertures are formed at intervals along the length of the rib.

A pair of receptacle spring prestressing or preloading guide projections 16 are formed on each end wall 11 extending away from the mating face towards the board engaging face at locations on each side of the slot and have lowermost entry ends formed with ramp or cam surfaces 16a. Outer surfaces of respective end walls are formed with grooves 18 extending between the mating and board engaging faces for the receipt of known metal mounting elements 35 of L-shape, as force fits, such mounting elements having transverse leg portions 36 at the mating face for connection to the circuit board by reflow soldering, securely to attach the receptacle connector 10 to the circuit board.

As best seen in FIGS. 1 and 2(b), the film circuit locating rib 11e and lower longitudinal edges of the side walls 11a and 11b are spaced from the circuit board by feet formed at opposite ends of the connector, defining a spring mounting member receiving recess above the circuit board.

The receptacle spring mounting member 20 is of generally channel-section having a central receptacle spring base mounting portion and mutually opposite, longitudinally extending film circuit locating side walls 25. A series of insertion guide pins 22 upstand at spaced apart locations from the upper surface of the receptacle spring base supporting portion together with a series of spaced apart retaining pins 23, shorter than the insertion guide pins. A pair of anchoring pins 21 depend from the lower surface of the receptacle spring supporting member for anchoring receipt in respective apertures in a circuit board. Pairs of cut-outs are formed in the receptacle spring base supporting member on respected opposite sides thereof at locations aligned with respective anchoring pins 21, as most clearly seen in FIGS. 3 and 6(a).

As shown in FIG. 6(c) a pair of retention pins 24 upstand from respective opposite ends of the receptacle of the spring mounting member and are receivable as a force fit in complementary sockets (not shown) in the end walls of the receptacle housing to securely assemble the receptacle spring mounting member therein.

The receptacle spring 40 is stamped and formed from a metal plate into a channel-section with a base wall 43 from opposite longitudinal sides of which upstand side walls 41 and 42, respectively, which walls are further bent to form convex, inwardly extending, film circuit pressing protuberances 41a and 42a having longitudinally extending axes of generation and defining between them a channel mouth of restricted size and which are reversely bent to extend outwardly at uppermost free ends forming part tubular, longitudinally extending stiffening portions 41b and 42b. Tab-like, cam following extensions 41c and 42c having inner edges 41d and 42d, respectively, extend longitudinally and laterally outwardly from opposite ends of the respective part tubular portions 41b and 42b for spring prestressing purposes.

Tabs 44, 44a are struck out from respective opposite side walls 41 and 42 at locations adjacent the base 43, bent to extend downwardly below the base and formed at free ends with laterally outwardly extending board anchoring and, preferably, electrically connecting, portions for surface mount connection to a circuit board. A row of retention and guide pin receiving apertures 45 are drilled or punched in the base 43 at locations corresponding to the locations of the guide, and retention pins 22 and 23.

As seen most clearly in FIG. 5, the precursor of the film circuit 31 is PTC and comprises a series of conductive layers or tracks 32a and 32b formed on a common surface of an insulating web 31 to extend in parallel relation away from a medial portion formed with a row of guide and retention pin receiving apertures 31a. It will be understood that the term flexible circuit includes any suitable form of flexible circuitry or flexible circuit board, as described in the parent application.

A longitudinally extending, strip-like, portion of the web, at a location remote from the medial portion, is cut away from each side of the medial portion to provide apertures or windows 31b through which individual conductors of trailing ends 32a, 32b of the film circuit are exposed for electrical connector to a circuit board when installed in the connector.

Prior to assembly of the receptacle connector, the peripheral portions of the film circuit, including the outermost rectangular conductive portions are also removed, for example, by severing with one line of severance extending along the outermost edge of respective windows 31b, as necessary for mounting in the receptacle connector.

As best seen in FIGS. 8(a), 8(b) and 8(c), the receptacle connector is assembled by firstly positioning the film circuit (with unrequired portions removed) in the receptacle housing with the medial part covering the lower surface of the rib 11e and opposite ends extending upwardly towards the mating face on respective opposite sides of the rib 11e into the cavity and folded back to form an M-shape so that trailing ends extend downwardly adjacent the side walls, out of the apertures at the mating face and contact areas are located in the cavity facing each other of opposite sides of the slot.

Alternatively, the film circuit 30 may be pushed directly into the cavity, possibly carried by the receptacle spring mounted spring premounted on the receptacle spring mounting member.

The receptacle spring 40 is then mounted on the receptacle spring mounting member by locating the base 43 on the locating portion with the guide and retention pins 22 and 23 projecting through the respective apertures 45 accurately positioning the receptacle spring on the receptacle mounting member. The subassembly so formed is then inserted through the aperture into the receptacle cavity with the receptacle spring protuberances on the side walls being flexed apart by the rib and riding thereover and the inner edges 41d and 42d of cam following extensions 41c and 42c, respectively, riding up the ramp surfaces 16a, flexing the protruberance apart adjacent the mouth until the camming extensions rest on uppermost straight portions with the receptacle spring in prestressed or preloaded condition.

During insertion, the insertion guide and retention pins 22 and 23 are received in the apertures 23 in the film circuit and in the apertures formed in the rib 11e with the guide pins projecting upwardly therefrom so that the film circuit is secured reliably and positioned accurately in the housing gripped between the base 43 of the receptacle spring and the lower surface of the rib with the film circuit end portions riding over respective protuberances.

At the same time, the film circuit locating walls 25 of the receptacle spring mounting member are pressed against portions of respective receptacle housing side walls defining the aperture by the walls 25 of the receptacle spring mounting member.

During final stages of assembly, the securing pins 24 of the receptacle spring mounting member are received as force fits in sockets in the receptacle housing which, together with the engagement of the guide and retention pins 22 and 23 in the apertures reliably, secures the film circuit and the receptacle spring mounting member in the housing.

The assembled receptacle connector is secured to the circuit board 1 by surface mount techniques, the anchoring pins 21 being received in apertures in the circuit board and connection of separated and exposed conductors of trailing end portions 32a to respective tracks of the circuit board by a reflow soldering technique. In addition, the tabs of legs 44 are also soldered to the circuit board and the feet 36 of the L-shaped anchoring members 35 which have been force fitted into respective grooves 18 at opposite ends of the receptacle housing are soldered to the board for additional anchoring.

As shown in FIGS. 9-13, the plug connector 50 comprises an outer housing 51 which receives a film circuit supporting member 60 carrying a film circuit 70.

The outer housing 51 is molded in one piece of plastic material into rectanguloid shape having opposite side walls 51a and 51b and opposite end walls 51c and 51d, respectively, extending between front, mating and rear board engaging faces. A base wall 52 extends transversely across the housing adjacent the board engaging face defining, with the side, and end walls, a receptacle housing receiving cavity open to the mating face. An elongate film circuit supporting member receiving aperture 52a extends centrally through the base wall 52. Columnar portions 58 upstand from the base wall at locations adjacent in space from the respective end walls at opposite ends of the aperture 52a and are joined at upper ends by a bridging portion 53 aligned over the aperture 50a and forming a leading end of the plug connector.

A row of apertures 53a and 53b are formed extending through the bridging portion 53. Attachment pins 55 depend from the base wall at locations between the columnar portions 54 and the end walls and grooves 57 are force fitted with L-shaped mounting members 75 having transverse feet 76, are provided in outside surfaces of the end walls in similar fashion to the receptacle connector.

The outside portions of the side walls are rebated adjacent the circuit board engaging face and a film supporting member receiving recess is formed under the base wall 53, outer wall parts of which diverge, providing film circuit locating shoulders adjacent the circuit board.

The film circuit 70 is similar in structure to the film circuit 30 shown in FIG. 5 and described above but the dimensions are different and corresponding parts are therefore indicated by respective, seventy series numerals, 71, 71a, 71b, 72a and 72b.

As shown in FIGS. 9 and 12, the film circuit supporting member 60 has a plate like film circuit supporting wall 61 upstanding from a transverse foot. The wall 61 is of slightly smaller cross section than the aperture 52a. A series of guide pin receiving apertures 63 and upstanding retaining pins 64 are formed in the upper leading end of the film supporting wall at intervals corresponding to the guide pin receiving apertures 53a and apertures 53b for alignment therewith and insertion therein on assembly of the film circuit supporting member with the outer housing 51.

As shown in FIG. 12, a compression spring retaining groove 62 extends completely around the film circuit supporting wall at a central location and a ring or band of elastomer 85 or similar, resilient material is seated therein.

In a modification, such spring retaining groove may be formed only on opposite faces of the film circuit supporting wall and the elastomeric material formed as two strips seated in respective grooves.

Two circuit board anchoring pins 65 depend from the underside of the foot and securing sockets 67 are formed in opposite ends thereof.

Two transverse grooves 60a are also formed in the undersurface of the foot or base, communicating with upwardly directed anchoring socket 66. An elongate metal mounting part 80, shown in FIG. 9, has longitudinally extending mounting arms 82 and pressure retention arms upstanding from opposite lateral sides are received as a force fit in the socket 66 to secure the mounting part of the film circuit supporting member with the mounting arms 82 extending horizontally.

The film circuit is installed on the film circuit supporting member with the aperture 71a receiving guide pin 64 and the ends dressed down opposite sides of the film circuit supporting walls with contact areas of the film circuit overlying the band spring 85. The self-assembly so formed is then inserted through the aperture through the cavity until the leading end of the film circuit supporting wall seats against the bridging portion 53 gripping the film circuit therebetween and the retention pins 64 are fitted into respective apertures 53b.

When so assembled, the insertion pin receiving apertures 63 are aligned with the apertures 71a of the film circuit 70 and the apertures 53a of the bridging portion 53.

The securing pins 55 of the housing are then received as force fits in the socket 67 of the film circuit supporting member completing securement of the assembly.

The film mating contact areas with tracks 72a and 72b are then exposed extending down opposite faces of the film circuit supporting wall in taut condition away from the mating face overlying the compressible springs 85 while end portions 70 are clamped between the base wall and the film circuit supporting member 60.

The retention arms 83 of the fastener 80 are force-fitted into respective sockets 66 in the base with tangs or protuberances 83a thereof biting into the plastics body for connection of the portions 82 by reflow soldering together with the exposed end portions of film circuits 72a and 72b to respective conductive tracks of the circuit board 2. When the anchoring pin 65 is inserted into an anchoring aperture in the circuit board and the feet 76 of mounting arms 75 are soldered to the circuit board.

On mating the plug and socket connectors, accuracy of alignment is assured by registration and receipt of the guide pins 22 in respective apertures 53a of the bridging portion and apertures 63 of the film surface supporting wall 61. During the mating movement, as shown in FIG. 14, the film circuit supporting member urges the receptacle spring protuberances 41a and 42a apart with resilient deflection thereof and enters the receptacle spring mouth so that conductive tracks 32a, 32b, 72a, 72b in respective contact areas of the film circuits 30 and 70 of the plug and receptacle are pressed into engagement by the receptacle spring 40 and the counter force of the resilient compression of the compression spring 85 thereby effecting electrical connection between corresponding conductive tracks on the circuit boards 1 and 2.

Thus, the cooperation of the receptacle and plug springs assures that a predetermined, constant contact pressure is obtained for all tracks in the respective contact areas even if the protruberances 41a and 42a are unevenly formed or inclined, the compressive force of the spring 85 providing the compensating or accommodating force.

The preloaded condition of the receptacle spring also, in practice, reduces the insertion force and effort (energy) of insertion with less spring movement necessary to obtain a given contact force and further, in view of the widened mouth, reduces frictional effects tending to abrade the film and resist insertion.

The precise dimensioning and positioning of the receptacle spring mouth obtained by such prestress also obviates or ameliorates undesirable deflections of the plug connector to one side on insertion into the receptacle spring.

In another example, shown in FIGS. 15-17, the receptacle connector 11' is similar to that described above and is mounted on a circuit board 1, but the plug connector 150 is not board mounted. In this example, the plug connector 150 comprises an outer housing 151, a film circuit supporting member 160, a film circuit 170 and a film circuit clamping means 190. The film circuit clamping means 190 has a central, elongate slot receiving a modified rear end of the film circuit supporting member trapping rearwardly extending trailing end portions of the film circuit therebetween and resilient locking arms 191 having hook-form ends and extending from respective opposite ends of the member and which engage in a snap action over locking grooves 153 of locking shoulders or projections 152 on end walls of the housing 151. The profiles of the opposed surfaces of the slot and film circuit supporting member ensure that good strain relief is provided for the film circuit even if pulled or snagged.

This embodiment is suitable for connection to other connectors e.g., daisy-chaining, as shown in FIG. 25, in which primed reference numerals indicate elements corresponding to those of FIGS. 15-17.

As shown in FIGS. 18 and 19, a further embodiment incorporates two channel section receptacle springs and two plug-like film circuit supporting members arranged in side-by-side relation in respective plug and socket housings which are otherwise similar to the first example.

In essence, the receptacle connector 21 is equivalent to two connectors of the first example sharing a common medial wall and comprises a housing 211 defining two plug receiving cavities 212 and 213 having slotted plug receiving mouths 212a and 213a, respectively, at a mating face. A pair of film circuit locating ribs 211e extend between end walls of respective cavities. The receptacle spring mounting member 22 has two receptacle spring locating portions in respective cavities and locating respective channel section receptacle springs 240.

The flexible circuit precursor 230 has two sets of conductive tracks 232a, and 232b and 233a, 233b, respectively, on opposite side portions of an insulating web, each having enlarged mating contact areas located on respective opposite sides of rows of medial locate retaining apertures 231a and 231b, respectively.

Respective film circuit portions carrying respective sets of conductive tracks are located by pushing into respective receptacle springs and retained therein by the receipt of guide pins 222 and retention pins (not shown) in respective apertures, in other respects being assembled in the receptacle housing in a similar fashion to the first example except that, an insulating web portion joining the two sets of conductive tracks extends between the two cavities clamped between a lower edge of the rebated wall and a clamping projection upstanding from the receptacle spring mounting member at a central location.

The plug connector 250 comprises an outer housing 251 defining a receptacle receiving cavity 258 opening to a mating face, a single film circuit supporting member 260 having a pair of bridging portions 253, 254 upstanding in side-by-side, parallel relation aligned over respective slotted apertures in a transverse base wall. A pair of film circuit supporting walls 261 and 262 upstand in side-by-side parallel relation from a common foot. Each film circuit supporting wall is formed with a groove receiving a resilient compression spring 285, similar to that of the first example. The film circuit is similar to that of FIG. 19 and installed in a similar manner to the installation of the first example with respective mating contact areas 232a, b and 233a, b overlying the compressible springs 285 and a joining web portion clamped between the foot of the film circuit supporting member and the base wall.

The connector assembly of FIGS. 21 and 24 incorporates a film circuit, the precursor of which is shown in FIGS. 22a, 22b and 23 and in which different portions of conductive track extend across opposite faces of an insulated web for protection and insulation thereof.

The film circuit of the invention may be contrasted with the prior approach as shown in FIG. 30 in which rows of mating contact conductor portions 303a, 303b are joined by linking conductor portions 304a, 304b which are on the same or common, front mating face of the web 301.

In particular, in the receptacle connector shown in FIG. 21 in which primed reference numerals indicate similar parts to the connector receptacle of the first example, the conductive tracks have mating contact portions 33'a and 33'b formed on the front mating face of the web 31' extending in respective rows away from circuit locating apertures 31'c on a medial portion of the web and which are connected by plated through-holes 31'f and 31'd to respective adjacent ends of linking or wiring conductive tracks 32'a, 32'b on the rear surface of the web 31'. The other ends of the linking conductive tracks 32'a,32'b are connected by plated through-holes 31'g and 31'e to respective board connecting portions 34'a, 34'b of the conductive tracks which extend across respective windows exposing them to a circuit board. An insulating coating 30'a covers the linking conductive tracks 32'a, 32'b for use when the spring is metal.

As in the previous example, portions of the precursor of the film circuit including the outer conductive tracks 34c and associated with indexing holes are removed before assembly in the connector housing.

As can be seen in FIG. 21, the mating contact portions 33'b overly the protruberances but the linking portions 32'b do not contact those of the plug connector on mating but will be protected from possible abrasion or peeling on mating in advance of the contact area which could otherwise possibly be caused by a high frictional mating force. The linking portions will also be insulated from the spring by the insulating layer 30'a and concealed from contact with any worm metal particles or powder inadvertently accumulated on the front face of the film which could cause a short circuit between the conductive tracks. Tips of board connecting portions 34'a, 34'b extend out of the housing separated and exposed at the board connecting face.

As the plug connector of FIG. 24 is similar to that of FIG. 9 (and FIG. 12), primed reference numerals have been used to indicate corresponding paths. The film circuit thereof is essentially similar to that of FIGS. 22a and 22b although differing in size, corresponding parts being indicated by series 70 reference numerals.

As stated above, FIG. 25 shows a connector similar to that of FIG. 17 but connected to an identical connector by film circuit in daisy-chain fashion. Primed reference numerals are used to indicate similar parts.

As shown in FIGS. 26 and 27, the film circuit precursor 170 has four rows of mating contact conductive track portions 173'a, 173'b and 174'a, 174'b arranged as two pairs with individual rows of each pair on respective opposite sides of apertures 172'a and 172'b on a front mating face of the web, each conductive track being connected to respective linking portions 176' on the rear face of the web like conductive through holes 175'a-175'd, respectively.

In another embodiment, the precursor of the film circuit shown in FIGS. 27 and 28 for a connector similar to that shown in FIG. 18, the rows of each pair of two pairs of rows of mating contact portions of conductive tracks 233'a, 233'b and 234'a, 234'b on the front, mating face of web 231' and on respective opposite sides of locating apertures of 232'a, 232'b, are connected by conductive through-holes 237'a, 237'b, and 238'b, 238'a to linking conductor portions 239'b, 239'a and 239'c, 239'd, respectively, on the rear face of the web, themselves connected by conductive through-holes 237'd, 237'c and 238'c, 238'd, respectively, to board connecting portions 235' and 236' exposed at windows 231'a and 231'b. As before, the outer conductor and associated web portions are cut away when mounting the film circuit in the connector. As

As shown in FIGS. 31-40, the receptacle connector 701 includes an outer housing comprising a sleeve-form main body 710 and a cover member 725, film positioning and clamping members 723, a channel-section receptacle spring 740 and a film circuit 730.

The main body 710, shown, more particularly in FIG. 4, is molded in one piece of suitable insulating plastic material and comprises a generally rectangular sleeve-form frame structure having opposed longitudinal side walls 711a and 711b joined by end wall portions 711d and defining a cavity open towards upper, mating and lower faces. An elongate rib 712 extends centrally of the body adjacent the lower face forming two apertures 710a and 710b at the lower face on respective opposite sides of the rib. The rib is formed with a series of guide pin receiving apertures 712b at predetermined intervals therealong and has a concave upper surface 712a.

Receptacle spring prestressing columns or pillars 713 of rectangular section upstand from opposite longitudinal ends of the rib at locations adjacent the ends of the body. Rectangular section spring locking sockets 715 having upwardly and inwardly tapering walls 715a culminating in upwardly facing latching shoulders are formed of each side of the socket 715. Film circuit supporting member anchoring socket 718 are also formed in a lower face and cover housing guiding and film circuit locating and locking projection 714 are formed on an upper face, both sockets and projections being on each side of the columns 713.

Circuit board anchoring posts 717 depend from feet 716 at respective opposite ends of the housing maintaining the side walls (in effect rebated) spaced above the circuit board. Locking sockets 16a are formed in each foot and looped stamped and formed metal mounting members 737, shown in FIGS. 35a and 35b, have anchoring tabs 739 with tangs 739a mounted therein with loop portions 736 trapping longitudinal extensions of the housing against the circuit board with under surfaces 738a of solder tab portions 738 soldered to the circuit board.

As shown in FIG. 39, the cover housing 725 has an upper wall 727 and opposite side and end walls 726a-d. The upper wall has a slot-form plug receiving mouth 727a and downwardly opening sockets 727b located at each corner thereof for receipt of locking projections 714 of the main body.

The receptacle spring 740 has channel side walls 741 upstanding from a base 743 defining a plug receiving face 748 therebetween. The side walls are formed with inwardly convex protuberances 741a, 742a, transversely bent upper end portions 741b and 742b from longitudinal extensions of which depend cam following projections 744. Latching posts with spring portions 745 at upper ends upstand from longitudinal extensions of each end of the base. A row of four apertures 747 are formed to extend along each side wall.

Anchoring and board connecting tabs 746 are struck out from respective opposite side walls and extend downwardly and inwardly for anchoring and electrical connection to a circuit board for mounting and shielding purposes.

As shown in FIG. 36, each film positioning and clamping member 723 is of L-section and formed with press-fitting projections 723a at respective ends and a land 723c with a film circuit engaging face 723b.

As shown in FIG. 37, the base member 720 is an elongate strip with raised end portions 721 and a raised central, supporting portion 720a from opposite longitudinal sides of which portions 720b taper to a circuit board engaging face. Two longitudinally spaced apart windows 722 for admitting tabs 746 of the receptacle spring are also formed therein.

The precursor of the film circuit 730 shown in FIG. 40(a) and (b) is symmetrical on each side of a center line, CL and has conductive paths or tracks 732a, 732b extending across insulating film or web. Windows 734a are cut out at each end to expose board connecting portions of the tracks to a circuit board. Before assembly in a connector, an outer portion of the film circuit is removed in addition to portions 734b. Tongue sections 733 remain projecting from respective opposite sides and are each formed with an apertures 733a surrounded by a conducting pad 733d.

In assembling the receptacle connector, the receptacle spring 740 carrying the film circuit 730 arranged therealong is inserted into the main body 710 with side walls 741 and 742 passing through respective apertures 710a and 710b, as shown in FIG. 34(a), and the film positioning and clamping members 723 are inserted into the main body to position the film circuit adjacent the receptacle spring, minimizing the area of circuit board occupied by the connector. The base member 720 and, finally, the cover housing 725 are mounted to complete the assembly.

When the receptacle spring is mounted on the main body the posts 745 are inserted through the rectangular socket 715 until the latches flex past the tapering surfaces 715a and resiliently engage over the shoulders in a snap action retaining the receptacle spring assembled with the housing. During insertion, the side walls are flexed apart by engagement of cam following projections 744 with respective opposite sides of caming posts or pillars 713 thereby prestressing the receptacle spring in a preloaded condition.

A film circuit is also secured by receipt of the pins 714 and apertures 733a therein.

The film positioning and clamping members 723 are retained in the main housing by press fitted receipt of projections 723a in sockets 718, the shoulder formed by the L-shape seating under the respective side walls.

The base member 720 is mounted on the main body by press-fitting the end portions 721 in the lower face thereof, retaining the film circuit between the spring base 743 and supporting portion 720a of the base member and between the tapered portions 720b and the film circuit engaging surface 723c of film portions and clamping members 723. The anchoring and connecting tabs 746 of the receptacle spring then extend through respective windows 722 in the base member exposed for connection to the circuit board.

In fitting the cover housing on the sub-assembly formed above, projections 714 of the main body are press or force fitted into the socket 727b. The tongue portions 733 of the film circuit are then clamped between the cover housing and the main body.

As shown in FIGS. 41-46, the plug connector 705 is similar to that of earlier embodiments having an outer housing 750 receiving a film circuit supporting member 760 supporting a film circuit 770.

The plug housing 750 has side walls and end walls 751a-751d extending away from a mating face to a base wall 752 having a film circuit supporting member receiving slot 752a and defining a receptacle connector receiving cavity 755. The flanged longitudinal extension 753 at each end have sockets 753a receiving metal fittings 1137 for attachment of the plug connector to a circuit board by surface mount techniques.

The underside of the base wall 752 tapers outwardly as it extends away from each side of the slot 752a providing an elongate recess communicating with sockets 754 at respective opposite ends for receiving the foot of the film circuit supporting member.

As shown in FIGS. 43(a)-43(e), the film circuit supporting member 760 comprises a film circuit supporting wall 761 upstanding from a transverse foot. Grooves 761a are formed in respective opposite sides or faces of the wall and received compressible elastomeric members 777. Guide projection 761b upstand from leading ends of the film circuit supporting wall for receipt, the respective apertures 712b of the receptacle connector rib 712 in the fully mated condition of the plug and receptacle connectors shown in FIGS. 46. The transverse foot tapers as it extends away from the film supporting wall providing inclined film supporting surfaces at 762a. Opposite ends of the foot have longitudinal extensions 763 formed with lateral tabs or projections for press fitting in the housing and depending circuit board anchoring posts 764.

The film circuit 770 shown in FIGS. 14(a) and 14(b) is similar to those of previous examples also being symmetrical with respect to the Center Line and comprises an insulating web 771, conductive tracks 772a and 772b, a row of medially locating apertures 773 and cut outs 774a and 774b.

Metal fittings or fasteners 1137 have portions 1138, 1138a and 1139 similar in structure to portions 738, 738a and 739 of the fittings of FIG. 35.

Assembly of the components of both plug and receptacle is effected quickly and with precision by the cooperative engagement of the guiding and securing portions, interengageable as press or snap fits.

Precise alignment both during and after mating of the plug and socket connectors is assured by receipt of guide pins 761b on the leading end of the film supporting wall of the plug in sockets 712b of the receptacle rib, the concave profile of the rib surface 712a providing a seat for the convex profile of the leading end of the film supporting wall 761 of the plug.

In the film circuit 92 according to the invention, shown in FIGS. 47a-47d, apertures 92c are formed in the insulating web 92a corresponding in size and location to the discrete reflow solder pads 84 exposing the metalized layers or tracks 92b, to the insulating web face, opposite to the conventional board engaging face, and forming individual solder receiving pockets or wells in which the discrete solder pads 84 are received when the film circuit is pressed insulating web face first, against the track 83a of circuit board 83. On reflow, the solder is trapped by the pocket walls defined by the edges of the apertures, remaining therein, thereby obviating risk of solder bridges and assuring reliable electrical connections.

The apertured film circuits are particularly suitable for use in the connectors described herein as, not only do the apertures enable accurate positioning of the film circuit tracks on those of the circuit board to be obtained by simply pressing the aligned film circuit against the circuit board so that the solder pads enter the pockets preventing the film circuit shifting across the board surface, but the confining action also avoids need for complex positioning apparatus during the reflow step. In addition, very close pitch of tracks on the film circuit can be obtained without risk of solder bridge formation, enabling connectors having many circuit paths to be made in very small sizes.