JPS6333854A - Integrated circuit package - Google Patents

Abstract

PURPOSE:To obtain an integrated circuit package not deformed due to a temperature change by bringing the difference of the linear expansion coefficient of a lead frame material and the linear expansion coefficient of a molding resin to 1.4X10<-5> or less. CONSTITUTION:The difference of the linear expansion coefficient of a lead frame material and the linear expansion coefficient of a molding resin is brought to 1.4X10<-5> or less. It is desirable on manufacture that a lead frame in which a plurality of lead frames 2 at a package unit are shaped is used as a lead frame 1 employed. The lead frame 2 is formed by an IC chip mounting section 2a for fitting an IC chip at a central section and eight lead sections 2b surrounding the mounting section 2a. The lead sections 2b are exposed from a resin surface, a package surface, under the state in which they are sealed subsequently with the molding resin, and employed as terminals. Air gaps 3 take a straight shape, but it is preferable that a lead frame manufactured through etching working is used for increasing adhesive force.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to integrated circuit packages.

(Prior Art) An integrated circuit package includes an IC chip, a lead portion as an external terminal for connecting the terminal of the IC chip to the outside, a lead frame for mechanically supporting the integrated circuit, and the IC chip and the lead frame. It consists of a package that serves as a housing and is entirely sealed with molded resin.

Such integrated circuit packages include resin-type and ceramic-type packages, each of which has advantages and disadvantages, but from a cost standpoint, resin-type packages are easier to use.

After connecting the IC chip to the lead part of the lead frame using one of these resin types, the lead frame and IC chip are sealed with molding resin so that the entire surface of the board part is exposed as a terminal on the surface of the package. There is an integrated circuit package that has stopped.

This type of integrated circuit package is compact in size, enables high packaging density of integrated circuits, is easy to manufacture, and has cost advantages, so it is used for integrated circuits that require high packaging density. It is especially used as an integrated circuit package for IC cards.

(Problems to be Solved by the Invention) However, since such an integrated circuit package has a planar two-layer structure consisting of a metal lead frame and a molded resin, it behaves like a bimetal due to temperature changes and is susceptible to deformation such as warping. This may cause malfunction of the IC chip loaded in the package and, in severe cases, may even destroy the package. In particular, the above phenomenon is caused by IC
This problem occurs during the mold resin curing process after the chip and lead frame are sealed with the mold resin, resulting in a reduction in package productivity.

(Means for solving problems) The present invention has been made in view of the above points.

The present inventor has proposed that if a lead frame material and mold resin are selected to create a package so that the difference between the coefficient of linear expansion of the lead frame material and the coefficient of linear expansion of the mold resin used in the integrated circuit puff cage is small, the temperature The present invention was achieved by discovering that it is possible to manufacture an integrated circuit package that does not undergo deformation due to changes.

That is, in the integrated circuit package of the present invention, the IC chip is connected to the lead portion of the lead frame, and then the entire surface of the lead portion is exposed as a terminal on the surface of the package.
An integrated circuit package in which a lead frame and an IC chip are sealed with a mold resin, wherein the difference between the coefficient of linear expansion of the lead frame material and the coefficient of linear expansion of the mold resin is 1.4 Xl, O-' or less It is characterized by

Hereinafter, the present invention will be explained based on drawings showing preferred embodiments.

FIG. 1 is a plan view showing an example of a lead frame 1 used in an integrated circuit package of the present invention, in which a plurality of lead frames 2 (the part surrounded by a broken line in the figure) are formed for each package. There is. As the lead frame 1 used in the present invention, it is preferable to use one in which a plurality of lead frames 2 are formed in package units.However, if there is a problem with the processing machine,
It may be of one shape.

The lead frame 2 includes an IC chip mount part 2a for installing an IC chip in the center, and this mount part 2a.
It is formed from eight lead parts 2b surrounding the lead part 2b. This lead portion 2b is later sealed with molded resin and exposed from the resin surface, that is, the package surface, and becomes a terminal, but the number is not particularly limited to eight, and it depends on the IC chip used. There may be as many as 6 pieces depending on the function. In addition, as shown in the figure, if the width L of the part located at the edge of the package is smaller than the width 2 of the part located in the center, the lead part 2b that becomes the terminal after packaging is Although it has the advantage of being able to prevent it from falling off from the package in the lateral direction, its shape is not limited to the shape of this embodiment, and may be tapered, for example.

However, as long as the adhesiveness between the mold resin and the lead frame is good, a straight shape with the same width may be used.

As the material of the lead frame 1, stainless steel is preferably used from the viewpoint of corrosion prevention of the lead portion 2b exposed on the package surface and low coefficient of linear expansion.
IS SUS304.5US430.5US31
6.5 US410 etc. are used, preferably S U 5304, S U 531, which are austenitic stainless steels that do not have magnetism that may cause IC chip malfunction.
6 etc. is used.

In addition, iron-based alloys such as 42 alloy or copper-based alloys such as KLF-5,0LIN194 used in -S lead frames can be used taking into account their linear expansion coefficients, but on the terminal surface, For the reasons mentioned above, it is desirable to apply gold plating or the like.

The smaller the coefficient of linear expansion of the lead frame material as described above is, the smaller the temperature change of the lead frame itself is, which is preferable. .8 xlO-'in/
A lead frame material with a coefficient of linear expansion of about in/'c is selected and used.

FIG. 2 shows a cross-sectional view taken along the line A--A in FIG.

The gap 3 between the lead part 2b and the IC chip mount part 2a is
When sealed with mold resin, it is filled with resin and serves as an anchor to firmly adhere the resin and lead frame, and its shape greatly affects the adhesive strength between the resin and the lead frame. Although not shown in the same figure, a gap 4 between the lead portions 2b and the lead portion 2b is also provided.
(Fig. 1) also plays a similar role.

The lead frame shown in Figure 2 is manufactured by stamping, and the gap 3 has a straight shape, but in order to increase the adhesive strength, a lead frame manufactured by etching may be used. It is preferable.

That is, the void 3 of the lead frame manufactured by etching takes various shapes depending on the etching method. For example, in the case of simultaneous etching on the front and back sides,
As shown in the figure, the shape is barrel-shaped with a large central part and a small opening, and when using the single-sided etching method, it becomes a trapezoidal shape (the smaller opening is the resin side) as shown in Figure 4, but eventually When sealing with mold resin, the mold resin filled in the gap acts as an anchor, so the entire mold resin does not easily come off from the lead frame, improving the adhesion between the lead frame and the encapsulated mold resin. will improve. Furthermore, if the surfaces of the IC chip mount part 2a and the lead part 2b are provided with unevenness 5 as shown in FIGS. 3 and 4, the contact area between the mold resin and the lead frame will increase, and the unevenness will serve as an anchor. None The adhesion between the mold resin and the lead frame is further improved. In the present invention, it is preferable that the shape is changed depending on the mold resin used, but the adhesive strength between the mold resin and the lead frame is good, and it is naturally not necessary to provide the lead frame unless it is particularly necessary.

Such irregularities can be formed by either a physical method such as polishing the lead frame with a sandbrush or a chemical method such as etching.

A predetermined amount of adhesive for bonding an IC chip is applied in a predetermined shape onto the IC chip mount portion 2a of the lead frame 2 as described above, and the IC chip is bonded onto the mount portion 2a.
An intermediate body before the chip and the terminal wire 2b are connected can be obtained. The above IC chip bonding process is carried out by fixing the lead frame using the terminal surface of the lead frame as a fixing surface using an air suction method or a clamping method using a jig. Since the lead frame has no protrusions and is flat, the lead frame can be securely and easily fixed to the processing machine fixing surface.

Next, the IC chip of the intermediate body and the lead part 2b are connected by wire bonding, but in this case as well, the terminal surface becomes the fixing surface as in the above adhesive process, and the intermediate body can be reliably and easily attached to the fixing surface of the wire bonding machine. Can be fixed.

The intermediate body, in which the IC chip and the lead portion 2b are connected by wire bonding, is molded into a predetermined shape by transfer molding using a molding resin to seal the lead frame and the IC chip to form a package.

In this package forming operation, if the mold resin bleeds onto the terminal surface of the lead portion 2b, it is necessary to remove the adhered mold resin by physical polishing or wiping with a solvent or the like.

As the molding resin used in the present invention, a wide variety of commonly used molding resins such as epoxy resins, silicone resins, and epoxy-silicone hybrid resins can be used, and their linear expansion coefficients are small. The temperature change of the mold resin itself becomes smaller, which is preferable, but considering the linear expansion coefficient of the lead frame, it is 1.5 xio-' to 3.5 xlO-'in/
It is preferable to use one having a temperature of about in /°C.

By selecting the mold resin and lead frame material that have linear expansion coefficients as described above, the linear expansion coefficient of the lead frame can be adjusted to lXl0-' to 1.8 Xl0-5in/in.
The maximum difference between the linear expansion coefficient of 7℃ and the mold resin is 1.4.
Although it is possible to obtain the package of the present invention with less temperature deformation by using X10-5, in order to obtain a package with even less temperature deformation, the difference must be 1. OXl0-
' is desirable.

A lead frame l having a plurality of packages formed as described above is replaced with a lead frame 2 for each package.
The integrated circuit package of the present invention can be obtained by cutting in the shape of .

FIG. 5 is a perspective view of the integrated circuit package 10 of the present invention, in which lead portions 2b, which are terminals, are exposed on the surface of the molded resin 13 constituting the package. As described above, the exposed lead 2b has a shape in which the width at the end of the package is smaller than the width at the center, thereby preventing the terminal 2b from falling off in the side direction.

FIG. 6 is a sectional view taken along line B-B in FIG.
A C chip 11 is bonded, and the IC chip 11 is connected to the lead portion 2b with a gold wire 12. The entire structure is sealed with a mold resin 13, and the mold resin 13 filling the gap 3 functions as an anchor for adhesion.

FIG. 7 is a perspective view of an IC card obtained by incorporating the integrated circuit puff cage 10 of the present invention obtained as described above into a plastic card, and FIG. 8 is a cross-sectional view taken along the line CC.

The integrated circuit package 10 is embedded in a recess provided in a predetermined portion of the card base material 20 so that its surface is flush with the surface of the card base material 20, and is firmly fixed with an adhesive 21.

When this card is inserted into a predetermined card processing machine, signals are exchanged between the card processing machine and the integrated circuit via the terminal 2b, and information is processed.

Furthermore, the integrated circuit package of the present invention can be used not only for cards but also for integrated circuits that require high packaging density.

(Effects of the Invention) In the present invention, in creating an integrated circuit package that can be compacted in size, enables high packaging density, and is advantageous in terms of cost, the linear expansion coefficient of the lead frame material and the mold resin are The lead frame material and molding resin were selected to create the package so that the difference between the linear expansion coefficient of
It is possible to provide a highly reliable integrated circuit package in which the C chip does not malfunction, and also to improve productivity in its manufacture. Therefore, an IC card using the integrated circuit package of the present invention has high reliability and does not malfunction even under severe card conditions.

Hereinafter, the present invention will be explained in more detail based on specific examples.

Example Three 0LIN194 alloy plates with a thickness of 0.15 mm (coefficient of linear expansion 1.63 x 10-5 in/in/'c) were prepared, and after washing and drying according to a conventional method, photoresist was applied to both sides of the alloy plates. A predetermined amount of photoresist film was formed by coating and drying. Next, 2On+m X with 8 lead terminals
Using a lead frame original plate in which five 20 mm+ package lead frames were connected, contact exposure and development were performed in a conventional manner, and then etching was performed simultaneously from the front and back of the alloy plate to obtain three lead frames used in the present invention. .

Next, place the obtained lead frame on an air suction stand so that the terminal surface becomes the fixed surface, securely fix it, and adhesively load the IC chip into each IC chip mount part using Gui adhesive. T by wire bonding machine
The C chip and the lead part were connected.

Next, epoxy resin M H19F-0157 (linear expansion coefficient 3.2 -'in/in/'c, manufactured by Matsushita Electric Works ■) and epoxy resin CV: 3soos
C linear expansion coefficient 2.4 Xl0-5in/in/'c
, Matsushita Electric Works Ltd.) by transfer molding to seal three IC chips in three lead frames, and then cut each package at a predetermined position to form three integrated circuit packages of the present invention. I got the kind.

Next, the obtained integrated circuit package was embedded in a plastic card so that its terminal surface was flush with the surface of the card base material to produce an IC card. Note that the package card base material was fixed with epoxy adhesive.

When the created IC card was inserted into a predetermined card processing machine, signals were exchanged between the card processing machine and the integrated circuit via the terminal, and information was processed successfully.

Example 2 5US304 with a thickness of 0.15 mm (yI expansion coefficient 1.
73XIO-'in/in/'c, manufactured by Dainippon Printing Co., Ltd.) were prepared, and in the same manner as in Example 1, three types of integrated circuit packages of the present invention were obtained.

Example 3 0.15mm thickness 42ALLOYC linear expansion coefficient 0.4
3 Xl0-'in/in/'c, manufactured by Dainippon Printing Co., Ltd.) were prepared, and in the same manner as in Example 1, three types of integrated circuit packages of the present invention were obtained.

Comparative Example The nine types of integrated circuit packages of Examples 1, 2, and 3 prepared as described above were subjected to a temperature cycle test (conditions: low temperature -55°C to high temperature 150°C repeated 100 times). However, the results shown in the table below were obtained, and the difference in linear expansion coefficient was 1.2 Xl0-'in/
It was confirmed that a value of in/'c or less is good.

Example 1 Example 2 Example 3 0LIN194 5LIS304 42ALLOYM
H19F-0157 Good Good Large deformation (0,
47) (0,37) (1,67)CV33
00S Good Good Destruction (0,77)
(0,67) (1,97)CV3500S
Large deformation Good Destruction (1,57) (1
, 47) (2, 77) Note: The numbers in parentheses in the table are (linear expansion coefficient of resin) - (linear expansion coefficient of frame material)
IO-'.

4. r: g: J side Figure 1 is a plan view of the lead frame used in the present invention.
FIG. 2 is a sectional view taken along the line A-A in FIG. 1, FIGS. 3 and 4 are sectional views of another embodiment of the lead frame at the same position as in FIG. 2, and FIG. Perspective view of the package,
6 is a sectional view taken along the line B-B in FIG. 5, FIG. 7 is a perspective view of an IC card using the integrated circuit crucible package of the present invention, and FIG. 8 is a sectional view taken along the line C-C in FIG. 7. It is a diagram.

1...Lead frame 2...Lead frame 2a for each package...IC
Chip mount part 2b...Lead part 3...Gap between IC chip mount part and lead part 4...Gap between lead part 2b 5...Irregularities on lead frame surface 10...Integrated circuit package 11...IC chip 12...Gold wire for connection 20...Card base (reverse 13...Mold resin 14...Adhesive for bonding IC chip 21...Adhesive applicant Dai Nippon Printing Co., Ltd. Company agent Patent attorney Atsumi Konishi Figure 2 Figure 3 Figure 4 J Figure 5 Uj!J Figure 7 Prisoner 8

Claims (4)

[Claims] (1) In an integrated circuit package in which an IC chip is connected to the lead portion of a lead frame, and the lead frame and IC chip are sealed with molding resin so that the entire lead portion is exposed as a terminal on the surface of the package.
An integrated circuit package characterized in that the difference between the coefficient of linear expansion of the lead frame material and the coefficient of linear expansion of the molding resin is 1.4×1.0^-^5 or less. (2) The integrated circuit package according to claim (1), wherein the lead frame is formed by etching. (3) The integrated circuit package according to claim (1) or (2), wherein the contact surface with the resin surface of the lead frame has an uneven shape. (4) Claim (1) characterized in that the width of the lead portion exposed to the resin surface of the resin mold is narrower at the end of the package than at the center of the package.
The integrated circuit package according to any one of items (3) to (3).