Flat flex cable (FFC) with embedded spring contacts for connecting to a PCB or like electronic device

[0001] This application is a continuation of U.S. patent application Ser. No. 11/265,205, filed on Nov. 3, 2005 which is a continuation of U.S. patent application Ser. No. 10/412,729 filed on Apr. 11, 2003.

[0002] This invention pertains to flat flex cable (FFC) with spring contacts at one or both ends, spring contacts at one end and exposed electrical leads at the other end or contact pads at one end and connectors at the other end. One application for the FFC is connecting a camera module as used in cell phones to a PCB or like electrical circuit.

[0003] Flat flex cable (FFC) is an existing product supplied by many vendors. Typically electrical traces embedded in insulation in the FFC make electrical connection with one or more electronic components at either end of the FFC. Socket or pin connectors are often used to attach the end of the FFC to the electronic component. These types of connectors have space limitations and are not considered to be reliable forms of electrical interconnect. The environment in which the FFC operates has an impact on the selection of materials for the FFC and the type of connectors at either end. FFC used in small scale environments require connectors with a small pitch and occupy little space. Existing connectors have housings and support structures that occupy space and therefore do not easily fit into tight spaces. It is desirable to eliminate these bulky connectors attached to the FFC and enable electrical connection in tight spaces and in areas in which the electrical components to be electrically connected are not in physical contact or spaced a distance one from another.

[0004] FIG. 1 shows a FFC with embedded springs connected to internal traces within the FFC.

[0005] FIG. 2 is a schematic diagram of an assembly consisting of a camera module as used in cell phones and a FFC with electrical traces connecting embedded spring connectors aligned to be clamped into the camera module and with embedded spring connectors at the opposite end of the FFC that clamp into a PCB or like device.

[0006] FIG. 3 is a schematic diagram of an assembly consisting of a camera module as used in cell phones, a FFC with embedded spring connectors aligned with contact pads on a camera module ready to be clamped into electrical contact.

[0007] FIG. 4 is a Cross Section of FFC with embedded spring contacts.

[0008] FIG. 5 is a view of FFC with its internal electrical traces connected to embedded spring contacts on one end.

[0009] FIG. 6 is an expanded view of the spring contacts as would be seen prior to attachment to pads or traces embedded within the FFC

[0010] FIG. 7 is an expanded version of embedded spring contacts on FFC. These contacts are electrically connected to traces embedded within the FFC not visible in this drawing for connection to a camera module.

[0011] FIG. 8 is embedded contacts on FFC affixed to an end to be inserted into a PCB clamp mechanism.

[0012] FIG. 9 is terminal ends of contacts that are formed as an uninterrupted continuum of electrical traces embedded in a FFC inserted into a clamping mechanism

[0013] FIG. 10 is a schematic diagram of a clamp on a PCB or like device, used to hold and align a camera module to contacts that are embedded on or within the FFC.

[0014] FIG. 11 is a schematic diagram of FFC with exposed electrical traces aligned to be inserted into a clamp containing spring contacts on a PCB or like electrical device.

[0015] FIG. 12 shows a receptacle containing electrical contacts on a PCB or like device for receiving FFC with either spring contacts or exposed electrical traces.

[0016] FIG. 13 shows a FFC with spring flanges aligned to be inserted into a receptacle mounted on a PCB or like device

[0017] FIG. 1 is a schematic of a flat flex cable (FFC) 100 is shown in a perspective view. At one end of FFC 110 are spring contacts 102 and at the other end are a second set of spring contacts 104 disposed on the opposite side of FFC 110 to spring contacts 102. The spring contacts 102, 104 are connected by electrical traces 106 embedded within FFC 100. The location of the spring contacts 102 and 104 may change as the design parameters require. Spring contacts 102 and 104 may be on the same or opposite side of FFC 110. Or, the spring contacts 102 and 104 may be placed at intervals along the length of FFC 110. The process for making the spring contacts 102 and 104 are disclosed and claimed in a co-pending patent application filed on ______ April, 2006, entitled A SYSTEM FOR CONNECTING A CAMERA MODULE, OR LIKE DEVICE, USING FLAT FLEX CABLES, by the same inventors and assigned to Neoconix, Inc.

[0018] Still referring to FIG. 1 FFC 110 electrical traces 106 are insulated over the length of FFC 110. The electrical traces 106 are then connected to spring contacts 102 and 104 by the process of forming by applying a sheet of conductive material such as BeCu to the area where the traces 106 terminate, placing a mask on the conductive sheet thereby defining the shape of spring contacts 102, 104 and locating the mask on an end of a trace 106, etching the mask to leave the three dimensional spring contact 102, 104 shape and singulate each spring contact 102, 104 to electrically isolate it from the others. The singulation process may include mechanical and chemical etching. The spring contacts 102 and 104 may be attached to traces 106 by metallurgical plating or conductive adhesion such as a silver filled adhesive to form a mechanical and electrical bond.

[0019] Referring to FIG. 2 at one end of the FFC 110 spring contacts 102 are aligned with electrical contacts (not shown) on camera module 110 as used in cell phones. A camera module clamp 108 engages spring contacts 102 on FFC 110 with the electrical contacts on the underside of camera module 110 resulting in a mechanical compression of the electrical contacts to complete an electrical connection. Clamp 108 is shown as a snap clamp. Any suitable clamping mechanisms may be used. An alternative approach is to attach a permanent cap to secure spring contacts 102 to camera module 110.

[0020] At an opposite end of FFC 110 spring contacts 104 are aligned to insert into a clamp 112 that may be solder mounted on a PCB (not shown) or similar electronic device. In this configuration, spring contacts 104 are on the opposite surface of FFC 110 to that of spring contacts 102. Clamp 112 may be attached to a PCB by any type of attachment method. Spring contacts 104 are clamped into electrical contact with electrical contacts on the PCB.

[0021] Referring to FIG. 3, electrical contacts 114 are shown on camera module 110 that are aligned with spring contacts 102 that when engaged by camera modules clamp 108 make electrical contact and secure FFC 110 at one end.

[0022] FIG. 4 is a cross section of FFC 110 with either spring contacts 102 or 104 bonded or formed on electrical trace 106. Also shown are the insulating layers 116 and 118. Insulating layer 116 may be a backing or supporting layer for electrical traces 106 which are interspersed between insulating layers 116 and 118. Insulating layer 118 has been exposed in selected regions to receive spring contacts 102 and 104. The insulating material may be of multiple suitable compositions that have the characteristics of flexibility, mechanical and thermal properties and suitability for etching or similar material stripping as needed. As an example and not a limitation of choices of materials, the insulation HyRelex™ supplied by Taconic, Petersburgh, N.Y. has suitable characteristics for use as the insulating material and can be made with electrodeposited copper traces 106. The selection of the insulation material and the arrangement of electrical traces 106 can be engineered to shield RF interference and EMI.

[0023] FIG. 5 is a perspective view of FFC 110 showing electrical traces 106 and spring contacts 104. In this configuration, spring contacts 104 are formed on electrical traces 106. Spring contacts 104, as shown in this configuration, are positioned on FFC 110 to be inserted into a clamp or PCB or like circuit (not shown). They may also be bonded on electrical traces 106 or adhered in any suitable fashion. Also shown are the insulation layers 116 and 118. The arrangement of the traces 106 in parallel lines is for illustration purposes only as is the parallel rows of spring contacts 104. Any configuration of electrical traces 106 and spring contacts 104 are contemplated by this invention. For instance, spring contacts 104 could be shaped as hinged, helical or spiral springs. Likewise, electrical traces 106 could be different lengths as needed for design reasons including RF and EMI design requirements.

[0024] FIG. 6 shows the FFC 110 with an end having the spring contacts 102 disposed outwardly on one end surface. The spring contacts are connected to electrical traces 106 within FFC 110 by a base ring 120 that is at the terminus of traces 106. Base ring 120 has a hole in its center that aligns with the hole in the base 122 of spring contact 102. The two aligned base sections are placed in physical contact with one another by adhesives or metallurgical bonding. The hole, or via, in the respective bases sections 120, 122 may be plated to create a continuous, or integral structure. The process for making the embedded spring contacts 102 has been described previously herein and by reference to co-pending U.S. patent application Ser. No. 11/265,205, filed on Nov. 3, 2005 which is a continuation of U.S. patent application Ser. No. 10/412,729 filed on Apr. 11, 2003.

[0025] FIG. 7 shows details of spring contacts 102 as they are formed on FFC 110 to electrical traces 106 previously described. Bases of spring contacts 102 are secured to traces 106. The spring contacts 102 as shown in this instance are levered arms. They can be any suitable shape that allows for compliance to the contacts to which they engage. The contacts could also be rigid, such as ball shaped, if that meets the compliance requirements of the installation such as where there are compliant springs on a camera module to which the contacts 102 engage.

[0026] FIG. 8 shows details of spring contacts 104 that are formed in such a way as to insert into a clamp to engage other contacts on an electrical component. The spring contacts 104 are angled at its base 122 away from the end of FFC 110 so that the spring contacts 104 slide into engagement in a clamp mechanism shown later in this document. Other arrangements of contacts may be used that allow the FFC 110 to engage with an electrical component.

[0027] FIG. 9 shows FFC 110 formed with one end as an uninterrupted continuum of electrical traces 124 embedded in a FFC for inserting into a clamping mechanism later shown. The exposed electrical traces 124 are supported by an insulating backing and may slip in or be set into a mechanism that secures the traces 124 into electrical engagement with electrical connectors.

[0028] FIG. 10 is a view of FFC 110 with spring contacts 104 inserted into open clamp 112. Clamp 112 is typically located on a PCB or similar electrical device. The spring flanges 104 align with electrical contacts on the PCB (not shown) when inserted into clamp 112. When the clamp 112 is engaged, spring contacts 104 are securely connected to the electrical contacts on the PCB thereby completing one or more circuits connected through electrical traces 106 in FFC 100.

[0029] Still referring to FIG. 10, the FFC 110 with its spring contacts 104 is inserted into clamp 112 ready to be clamped into engagement with electrical contacts on a PCB (not shown) on which clamp 112 rests.

[0030] FIG. 11 Shows the FFC 110 with exposed electrical traces 129 (underside of FFC 100) positioned to be inserted into clamp 112 that has within it spring contacts 126 formed on a board 128 or similar structure, that could be a PCB, with electrical traces 130 connected to spring contacts 126. After the FFC 110 and exposed electrical traces 129 are inserted into clamp 112 in alignment with spring contacts 126, clamp 112 is closed to secured FFC 110 and its exposed electrical traces 129 in electrical contact with spring contacts 126 by compression of the clamping mechanism.

[0031] FIG. 12 shows a receptacle 132 mounted on a PCB 128 or similar structure with electrical contents within (not shown). The electrical contacts within receptacle 132 can be spring contacts, electrical pads or traces as the design requires. For instance if the FFC 100 has exposed electrical traces to be inserted into the receptacle the electrical contacts within the receptacle could be spring flanges. And the reverse is true if the FFC 110 has spring flanges 104 then the electrical contacts within receptacle 132 could be electrical traces or pads. Also shown are electrical traces 130 that exit the receptacle area and which electrically connect the inserted FFC 110 to electrical components (not shown) on PCB 128.

[0032] FIG. 13 shows FFC 110 from the underside with spring contacts 104 aligned to be inserted into receptacle 132 to engage electrical contacts, including without limitation pads or traces (not shown) within the receptacle 132.

[0033] Yet another variation of the process to manufacture FFC 110 is to use build up techniques described above to embed conductive material that terminates in pads on which to mount spring contacts 104 in layers of flexible dielectric materials. Circuits are formed on flex material with surface mount pads at a terminus and spring contacts 104 are laminated onto the pads by adhesives, typically acrylic. The springs 104 and pads are then plated to form an integral structure. The construction of these pads as part of the manufacture of the flat flex material eliminates the steps of stripping the insulation away from the conductive traces and bonding pads to the base ring 120 of the traces 106.

[0034] Variations in materials, manufacturing techniques and configuration of components are contemplated by this invention. Different views of the inventions are shown for illustration purposes and do not limit the configurations and arrangement of components of the invention.