US 5,281,848 AGrant
Tape Carrier Semiconductor Device
Issue Date:1994-01-25
•6 Claims
•4 Drawing Sheets
Abstract
A tape carrier semiconductor device has a resin sealed area not much larger than the size of the semiconductor chip, e.g. substantially not exceeding 2 mm to the outside. A device hole is not larger than an area formed by extending the outer periphery of the semiconductor chip to the outside by 0.3 mm and an epoxy resin of 500-1200 ps in viscosity is used for sealing the chip.
Metadata
Assignee
- Sharp Kabushiki Kaisha
Inventors
- Yasunori Chikawa
- Yoshiaki Honda
- Katsunobu Mori
- Naoyuki Tajima
- Takaaki Tsuda
- Takamichi Maeda
Application Information
Application Number:US 7964315
Filing Date:1991-11-22
Priority Date:1990-12-11
Art Unit:258
Classifications
IPC:
H01L 2328
Field of Search:
35725772;74666;787;667;668;676;730;735
Patent Drawings (4 sheets)
Description
Background of the Invention
1. Field of the Invention
The present invention relates to a tape carrier semiconductor device, and, more particularly, to a tape carrier semiconductor device of a smaller external size capable of higher density mounting of semiconductor devices.
2. Description of the Related Art
Heretofore, sealing resins for tape carrier semiconductor devices have been selected with priority being given to thinning the thickness of the resin applied to the semiconductor devices. With respect to the viscosity of the resin, liquid resins having a viscosity ranging from 100 to 150 cps are widely used with the device hole size usually equal to the chip size plus 0.6-1.0 mm, and the size of the resulting resin sealed area being about the chip size plus 4-5 mm.
A technique capable of controlling the size of the resin sealed area to a range of the chip size plus 1-2 mm has not yet been available.
The size of the resin sealed area is mostly left to natural phenomena, e.g., after pouring a sealing resin, the natural extension of the sealing resin is allowed until the natural extension stops.
Viscosity of liquid resins used heretofore is so low that the area covered by the sealing resin extends too widely and its size is difficult to control.
Even if the resin viscosity is raised, the sealed area cannot be controlled to a desired size of area, and/or LSI chips cannot be fully covered so that there is a reliability problem.
For the purpose of controlling the size of a resin sealed area, there is a method of printing a paste sealing resin on the tape. Though this method can control the resin sealed area at the side of the chip on which the paste sealing resin is printed, it is diffcult to control the extent of the sealing resin flowing to the opposite side of the chip through a gap between the LSI chip and the device mounting hole in the tape.
Summary of the Invention
An object of the present invention is to provide a tape carrier semiconductor device having a resin sealed area covering the semiconductor chip which is within an area formed by extending the outer periphery of the semiconductor chip to the outside by 2 mm.
According to the present invention, there is provided a tape carrier semiconductor device which comprises a semiconductor chip set at a device mounting hole provided in the tape carrier and sealed by applying an epoxy resin having a viscosity of 500-1200 ps (poises) thereto, the inner periphery of the device mounting hole being within an area defined by the outer periphery of the semiconductor chip and a curve formed by extending the outer periphery of the semiconductor chip to the outside by 0.3 mm.
Brief Description of the Drawing
FIG. 1 is a plan view of a tape carrier semiconductor device sealed with an epoxy resin according to the present invention;
FIG. 2 is a plan view of a tape carrier semiconductor device of the present invention before being sealed with an epoxy resin;
FIG. 3 a plan view of a conventional type carrier semiconductor device sealed with a liquid resin; and
FIG. 4 is a graph showing the relationship between resin viscosity and resin sealed area.
Description of the Preferred Embodiments
The present invention is explained in detail in the following text with reference to the accompanying drawings.
FIG. 1 illustrates a tape carrier semiconductor device sealed with an epoxy resin of the present invention.
A lead pattern 6 is provided on a substrate 5 by using an adhesive such as an epoxy resin. A solder resist 7, for example, composed of an epoxy resin, is furnished for protecting minute patterns and decreasing connecting resistances.
LSI chip 2 disposed within a device mounting hole (not shown in FIG. 1, but corresponding to 4 in FIG. 2) is sealed with an epoxy resin 1 (crosshatched) having a viscosity of 500-1200 ps. LSI chip 2 is also covered with the epoxy resin although crosshatching is not used there so as to more clearly show the position of LSI ship 2.
In FIG. 1 A' and B' represent the transverse and longitudinal dimensions of LSI chip 2, respectively and A and B represent the transverse and longitudinal dimensions of the resin sealed region, respectively. Each of (A-A')/2, (B-B')/2 and the distance between a vertex of LSI chip 2 and that of the resin sealed area corresponding to said vertex of LSI chip 2 is 2 mm or less.
FIG. 2 shows a tape carrier semiconductor device of FIG. 1 which has not yet been sealed with the epoxy resin. In FIG. 1 and FIG. 2, like reference numerals show like parts.
LSI chip 2 is set at device mounting hole 4 and inner leads 3 are connected with LSI chip 2.
C and D represent the transverse and longitudinal dimensions of device hole 4, respectively, and A' and B' represent the transverse and longitudinal dimensions of LSI chip 2. Each of (C-A')/2, (D-B')/2 and the distance between a vertex of LSI chip 2 and a vertex of device hole 4 corresponding to the vertex of LSI chip 2 is 0.3 mm or less.
FIG. 3 shows a conventional tape carrier semiconductor device in which LSI chip 2 has been sealed with a conventional liquid resin having a viscosity of 100-150 cps applied thereto. In FIG. 1 and FIG. 3, like reference numerals indicate like parts for ease of comparison.
In FIG. 3, A and B represent the transverse and longitudinal dimensions of the resin sealed region, respectively. A' and B' represent the transverse and longitudinal lengths of LSI chip 2, respectively. Each of (A-A')/2 and (B-B')/2 exceeds 2 mm.
A feature of the present invention is that a particular range of viscosity of the sealing resin is used and the relation between the size of the device hole and the size of LSI chip is defined so as to control the resin sealed region.
FIG. 4 illustrates a relationship between the viscosity of an epoxy resin and the resin sealed region in the case where the device mounting hole size is equal to (chip size +0.2 mm) (i.e. the distance between the inner pheriphery of the device mounting hole and the outer periphery of the LSI chip being 0.2 mm).
The ".alpha." in FIG. 4 stands for the distance between the outer periphery of the LSI chip and the outer periphery of the resin sealed region.
In FIG. 4, the resin viscosity giving the resin sealed region which is equal to (chip size+1 to 2 mm) (i.e. .alpha.=1 to 2 mm) is 500-1200 ps.
The lower limit of the resin sealed region is selected to be (chip size+1 mm) (i.e. .alpha.=1 mm) here since defective sealing is liable to occur when the resin sealed region is less than (chip size+1 mm).
The curve in the graph of FIG. 4 is obtained when the device mounting hole size is equal to (chip size+0.2 mm). However, a curve similar to the curve, in FIG. 4 is obtained until the device mounting hole size increases to (chip size+0.3 mm) (i.e. the distance between the inner periphery of the device mounting hole and the outer periphery of the LSI chip).
When the epoxy resin viscosity is higher than the above-mentioned upper limit or the device mounting hole size is larger than the above-mentioned upper limit, the epoxy sealing resin can not completely cover the inner leads connecting with an LSI chip or with an LSI chip and a tape carrier pattern, and therefore, the reliability and the mechanical strength are problematic.
On the contrary, when the epoxy resin viscosity is lower than the lower limit, i.e. 500 ps, the resin sealed region extends too far.
When the gap between the LSI chip and the mounting device hole is too small, the epoxy resin for sealing cannot flow through the gap and thereby, can not reach the back surface of the LSI chip. Therefore, the reliability is problematic.
As a sealing resin, an epoxy resin having a viscosity of 500-1200 ps is used.
Representative epoxy resins are glycidyl ether type epoxy resins. Exemplary suitable epoxy resins are bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol novolaks type epoxy resins and the like.
Materials which are in contact with the epoxy sealing resin are, for example, substrates of the tape carrier. As the substrates, various materials may be used, and are usually resin materials. Exemplary suitable resin materials include polyimide resin films, glass epoxy substrates and polyester resin substrates.
In addition, as other materials in contact with the epoxy sealing resin, there may be mentioned a solder resist 7 as shown in FIG. 1.
According to the present invention, the degree of extension of the epoxy sealing resin having a viscosity of 500-1200 ps varies somewhat depending upon the kind of resin material, but is not too much affected by the kind of resin material.
The method of effecting sealing of the LSI chip with the epoxy sealing resin is not particularly critical. For example, the epoxy resin having a viscosity of 500-1200 ps may be dropped to the LSI chip.
The procedure for sealing the chip may be carried out following prior art procedures, for example, applying the epoxy resin to the chip and allowing it to extend naturally until its flow stops.
For example, an LSI chip of 1.3 mm.times.14 mm in size was put on a film carrier at a device mounting hole such that the gap between the inner periphery and the outer periphery of the chip was about 0.1 mm. Then about 13 mg of an epoxy resin having a viscosity of about 800 ps was dropped on the chip. The resulting resin sealed region was about 3.3 mm.times.16 mm in size.
It is not always necessary that the gap between the inner periphery of a device mounting hole and the outer periphery of a semiconductor chip is the same at every position of the periphery, as long as the gap size is within the range as defined in the present invention. For example, the gap size at a portion where the number of inner leads is smaller is made narrower than the gap size at a portion where the number of inner leads is larger. Such difference in gap size is desired so as to avoid nonuniform flows to the back surface of the chip due to the difference in the number, of inner leads overhanging the device mounting hole.
As described above in detail, according to the present invention, the problem of the resin sealed region affecting the determination of the outer size of a tape carrier semiconductor device can be solved. As a result, there is produced a subminiature tape carrier semiconductor device of which resin sealed region is within an area formed by extending the periphery of the semiconductor chip to the outside by 2 mm.
For example, the present, invention is particularly effective to decrease the resin sealed area in a liquid crystal driver so as to lessen the outer periphery of portion other than the display portions.
Claims
What is claimed is:
1. A tape carrier semiconductor device which comprises: a semiconductor chip set within a device mounting hole provided in the tape carrier and sealed therein by an epoxy resin having a viscosity of 500-1200 ps when applied thereto, the inner periphery of the device mounting hole being within an area defined by the outer periphery of the semiconductor chip and a curve formed by extending the outer periphery of the semiconductor chip to the outside by 0.3 mm, the curved epoxy resin filling a gap between the chip and the mounting hole and extending beyond the edges of the chip onto the tape carrier by a maximum dimension of no more than 2 mm.
2. The tape carrier semiconductor device according to claim 1 in which a gap size between the inner periphery of the device mounting hole and the outer periphery of the semiconductor chip is narrower at a first portion than at a second portion where a number of inner leads is larger at the second portion than at the first portion.
3. A tape carrier semiconductor device comprising: a semiconductor chip; a tape carrier having a device mounting hole therein that is larger in size than said chip; said chip being disposed within said hole to define a gap having maximum dimension of no more than 0.3 mm between the outside edges of said chip and the inside edges of said hole; and a cured epoxy resin filling the gap between said chip and said hole and extending beyond the edges of said chip onto said tape carrier by a maximum dimension of no more than 2 mm.
4. A tape carrier semiconductor device comprising: a semiconductor chip; a tape carrier having a device mounting hole therein that is larger in size than said chip; said chip being disposed within said hole to define a gap having a maximum dimension of no more than 0.3 mm between the outside edges of said chip and the inside edges of said hole; a cured epoxy resin filling the gap between said chip and said hole and extending beyond the edges of said chip onto said tape carrier by a maximum dimension of no more than 2 mm; wherein said chip has a differing density of lead connections per unit distance along its edges and wherein the gap dimension between the chip and the hole along the chip edges is directly related to the density of lead connections thereat.
5. A tape carrier semiconductor device comprising: a tape carrier to define a semiconductor chip disposed within a hole in the carrier having a gap of no more than 0.3 mm therebetween which gap is filled with a cured epoxy resin that extends beyond the edges of said chip by no more than 2 mm.
6. A tape carrier semiconductor device comprising: a tape carrier to define a semiconductor chip disposed within a hole in the carrier having a gap of no more than 0.3 mm therebetween which gap is filled with a cured epoxy resin that extends beyond the edges of said chip by no more than 2 mm; wherein said chip has a varying numbers of lead connections made to its edges and wherein said gap dimension varies along the chip edges as a function of the number of lead connections made thereto.
Patent Citations (5)
Non-Patent Literature (2)
- Patent Abstracts of Japan, vol. 10, No. 244, 22 Aug. 1986, and JP-A-61 075 549, 17 Apr. 1986.
- Patent Abstracts of Japan, vol. 10, No. 302, 15 Oct. 1986, and JP-A-61 115 342, 2 Jun. 1986.