JPH11220054A - Method of pasting adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To paste an adhesive sheet to a tape carrier without giving rise to bubbles between the adhesive sheet and a wiring pattern. SOLUTION: When an adhesive sheet 10 is pasted onto a tape carrier 1 under heating, while pressuring it after die cutting into an arbitrary form, the process from die cutting to pasting is performed in vacuum. In short, when pasting the adhesive sheet 10 consisting of thermosetting material or mixture between thermosetting material and a thermoplastic material under heating while pressurizing it after die cutting in optional form, the process from die cutting to pasting is performed in vacuum. Moreover, a wiring board consists of a tape carrier 1, and the adhesive sheet 10 is pasted onto the wiring pattern of the tape carrier 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for attaching an adhesive sheet onto a wiring pattern of a tape carrier or the like.

[0002]

2. Description of the Related Art With the downsizing of equipment, miniaturization of semiconductor devices is also required. In response to this, various packaging methods are being studied. One of them is to use a TAB to attach a semiconductor chip using an adhesive sheet.
(Tape Automated Bonding) There is a type that is attached to a wiring pattern such as a tape carrier.

[0003] As one method of attaching this adhesive sheet to a carrier tape, an adhesive sheet formed into an appropriate shape is pressed while heating with a press and attached onto a wiring pattern. There is a method of bonding by heating and pressing.

For example, a COL that enables high-density mounting
Adhesives (thermoplastic and thermosetting adhesives, etc.) are pre-applied to one or both sides of a high heat-resistant polyimide film for mounting semiconductor chips on lead frames with (Chip on Lead) or LOC (Lead on Chip) structures. There is a film which is put to practical use as a prefabricated lead frame by attaching a film with an adhesive. A punching die is used to attach the film to the lead frame, and a punching punch that punches the film placed on the die into a predetermined shape in cooperation with a stripper, and a lead frame below the punching punch. It is composed of a heater block mounted on it and punches the film into a predetermined shape by lowering the punch.Then, the punched film is sandwiched between the heater block and the lead frame below it, and the film is thermocompressed at a predetermined position on the lead frame. doing.

Recently, a so-called chip size package (CSP) has attracted attention as a packaging technology suitable for high-density and highly reliable connection and low-cost production. The package form of this CSP is mainly ball grid array (Ball Grid Array)
In which the size of the package is substantially equal to the size of the chip.

FIG. 6 shows a package structure of a conventional CSP. In the CSP 20, a flexible wiring board, that is, a tape carrier 23, is provided on the surface of the semiconductor chip 21 with an elastic adhesive (elastomer adhesive) 28 (thickness of 50 to 100).
μm) and sealed. The leads 25 of the tape carrier 23 are connected to the electrode pads 22 on the four sides of the chip 21.
Are connected by the TAB method. The tape carrier 23 has a two-layer structure including a copper wiring layer 24 and a dielectric layer 23a of a polyimide film. The leads 25 are made of gold plating or copper wiring itself. The bumps 27 of the external terminals are formed in the via holes 26 of the tape carrier 23 and are made of gold / nickel plating or solder. The array pitch of the bumps 27 is 0.5 mm or 1.0 mm. The optional protection frame 29 is attached with a resin 30.

Here, the adhesive between the semiconductor element and the tape or the printed wiring board having the wiring pattern is applied by applying an elastomer adhesive by a screen printing method or the like, and then press-bonding the two and heat-curing. It is also considered effective.

[0008]

However, when the adhesive sheet is pasted on the wiring patterns described above, if the space between the wiring patterns is narrow, bubbles may be formed at the interface of the adhesive. These bubbles cause problems such as generation of voids at the time of sealing and generation of blisters due to post-heating.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide an adhesive sheet which can be adhered without generating air bubbles between an adhesive sheet and a wiring pattern and which can prevent blistering during sealing. Is to provide a method of attaching.

[0010]

According to one aspect of the present invention, there is provided a method for attaching an adhesive sheet comprising a thermosetting material or a mixture of a thermosetting material and a thermoplastic material. The adhesive sheet is stuck on the wiring board under heating while applying pressure in a vacuum.

According to a second aspect of the present invention, there is provided a method for attaching an adhesive sheet comprising a thermosetting material or a mixture of a thermosetting material and a thermoplastic material, wherein the adhesive sheet is punched into an arbitrary shape and heated under pressure. When affixing on a wiring board below, from punching to adhering are performed in a vacuum.

According to a third aspect of the present invention, there is provided a method for attaching an adhesive sheet, wherein the wiring substrate according to the second aspect is formed of a tape carrier, and the adhesive sheet is attached on a wiring pattern of the tape carrier.

In the present invention, when the adhesive sheet is attached on the wiring board, the tape carrier or the wiring pattern thereof, the attaching operation is performed in a vacuum. Therefore, air does not get caught in the lower surface of the adhesive sheet. Therefore, the attachment can be performed without generating a void between the adhesive sheet and the wiring pattern. As the vacuum level, a commercially available vacuum pump may be used as long as it is sucked in a closed space.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

FIGS. 1 and 2 show the configuration of a TAB tape carrier for a semiconductor device of the above-described chip size package (CSP).

The TAB tape carrier 1 has a two-layer structure having a base film 2 made of a polyimide film and a wiring pattern formed of copper foil and partially including inner leads 4 and lands 5. Land 5 is wiring pattern surface 3
The inner leads 4 extend from the lands 5 to the peripheral windows 6 provided so as to surround the wiring pattern surface 3, respectively. It is connected to the peripheral pads of the chip. The land 5 communicates with the opposite side of the base film 2 through the via hole 7, and a solder ball 8 as a bump of an external terminal is mounted thereon as shown virtually. Reference numeral 9 denotes a perforation hole for feeding.

The wiring pattern surface 3 of the tape carrier 1
An adhesive sheet 10 made of a thermosetting material or a mixture of a thermosetting material and a thermoplastic material is attached thereto, and a semiconductor chip (not shown) is adhered to the tape carrier 1 via this. Then, the inner leads 4 of the tape carrier 1 are connected to the peripheral pads on the four sides of the semiconductor chip by the TAB method as in the case of FIG. Therefore, the electrical connection reaches the bump terminals from the pads on the outer periphery of the chip via the tape wiring by the inner leads 4 in the lateral direction.

The adhesive sheet 10 is made of an elastomer adhesive made of an epoxy resin composition in a semi-cured state, and is pressed onto the TAB tape carrier 1 only at a portion to be bonded to a semiconductor element under vacuum. And heat cure. This is performed by bonding the adhesive sheet 10 onto the wiring pattern surface 3 of the tape carrier 1 under heating, while punching and pressing the adhesive sheet 10 into an arbitrary shape under vacuum. All processes from the punching to the attachment are performed in a vacuum. As a vacuum level, a commercially available vacuum pump may be used as long as it is sucked in a closed space.

Therefore, when the adhesive sheet is pressed onto the wiring pattern, the adhesive sheet can be adhered to the lower surface of the adhesive sheet without entraining air, whereby a void is generated between the adhesive sheet and the wiring pattern. Can be prevented. For this reason, the sheet obtained by this does not cause blistering even by heating after the moisture resistance test.

In order to obtain a CSP semiconductor device, the TAB tape carrier 1 having the above-mentioned epoxy resin adhesive sheet 10 is strictly aligned with the semiconductor chip 21 and then heated by a molding press heated to a predetermined temperature. Is press-bonded for a predetermined period of time. Thereafter, the inner leads 4 of the TAB tape carrier 1 are bonded to the electrode pads 22 of the semiconductor chip 21, and the bonding leads are formed of a sealing resin 3 made of a highly adhesive liquid silicone resin.
Seal with 0 and thermoset. Furthermore, solder balls 8
Is used to form bumps on the electrode pads 22 of the TAB tape carrier 1 for connection to external circuits. Through the above steps, a CSP semiconductor device is obtained.

[0021]

(Embodiment) An adhesive sheet 10 mainly composed of an epoxy resin as an elastomer 11 is placed on a wiring pattern of a TAB tape carrier 1 shown in FIG.
While applying a pressure of 30 kg / cm ² , the sheet was heated at a temperature of 130 ° C. for 4 seconds and attached. FIG. 1 shows the result of observing the appearance of the adhesive sheet 10 stuck according to the present embodiment. No void was observed between the adhesive sheet 10 and the wiring pattern in the sample affixed according to this example.

COMPARATIVE EXAMPLE As a comparative example, an adhesive sheet 10 mainly composed of the same epoxy resin was stuck on the wiring pattern of the TAB tape carrier 1 shown in FIG. 3 under atmospheric pressure. In this comparative example, the adhesive sheet 10 was stuck under the same conditions as in the example, except that it was not performed in a vacuum. FIG. 4 shows the result of observing the adhesive sheet 10 attached according to this comparative example. FIG. 5 is an enlarged view of a part thereof.

As shown in FIGS. 4 and 5, when the adhesive sheet 10 is adhered under the atmospheric pressure, the space between the land 5 and the inner leads 4 is provided between the adhesive sheet 10 and the wiring pattern. Generation of many voids 13 was observed at the time of reading.

As can be seen from the comparison between the above example and the comparative example, it is clear that the adhesive sheet can be attached without generating voids 13 according to the adhesive sheet attaching method of the present invention. .

Both samples were left in a thermo-hygrostat at 85 ° C. × 85% RH for 48 hours, taken out and placed on a heat block at 300 ° C. No change was observed in the samples stuck according to the examples. However, the sample obtained from the comparative example had blistering.

It is clear that the adhesive sheet bonded according to the present invention can obtain a bonded sample which does not generate blisters even when heated after the moisture resistance test.

In the above embodiment, the adhesive sheet 10 is attached to the wiring pattern of the TAB tape carrier. However, the adhesive sheet 10 is attached to a wiring board other than the TAB tape carrier. The present invention is also effective in the case of attaching. Of course, it can be attached to the wiring pattern surface without any problem.

In the case of the above embodiment, the adhesive sheet 10
Is composed mainly of a thermosetting epoxy resin as the elastomer 11, but an adhesive layer made of a thermosetting resin such as an epoxy resin or a thermosetting polyimide resin is formed on the elastomer 11 made of an epoxy resin. 12 may be formed.

The adhesive sheet 10 may be made of either a thermosetting material or a mixture of a thermosetting material and a thermoplastic material. The surface of the adhesive is preferably tack-free (no tackiness), and it is preferable to use one having a softening point of 30 ° C. or higher.

[0030]

As described above, according to the first to third aspects of the present invention, when the adhesive sheet is attached to a wiring board, a tape carrier, or its wiring pattern, the attaching operation is performed. Since the operation is performed in a vacuum, no air is trapped on the lower surface of the adhesive sheet. Therefore,
The bonding can be performed without generating a void between the adhesive sheet and the wiring pattern. For this reason, the sheet obtained by this does not cause blistering even by heating after the moisture resistance test.

[Brief description of the drawings]

FIG. 1 is a view showing a transmission surface of a pasted sample obtained according to an example of the present invention.

FIG. 2 is a sectional view taken along line BB 'of FIG.

FIG. 3 is a diagram showing a wiring pattern of a TAB tape carrier used in an example of the present invention.

FIG. 4 is a view showing a transmission surface of a pasted sample obtained in a comparative example.

FIG. 5 is an enlarged view of a pasted sample obtained according to a comparative example at a land side.

FIG. 6 is a cross-sectional view showing a structure of a conventional semiconductor device of a chip size package.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 TAB tape carrier 2 Base film 3 Wiring pattern surface 4 Inner lead 5 Land 6 Window 7 Via hole 8 Solder ball 9 Perforation hole 10 Adhesive sheet 11 Elastomer 12 Adhesive layer 13 Void

Claims (3)

[Claims] An adhesive characterized in that an adhesive sheet made of a thermosetting material or a mixture of a thermosetting material and a thermoplastic material is adhered onto a wiring substrate under heating while applying pressure in a vacuum. How to attach the sheet. 2. An adhesive sheet made of a thermosetting material or a mixture of a thermosetting material and a thermoplastic material is punched into an arbitrary shape, and is pressed into a pressurized sheet while being applied to a wiring board while heating. A method for adhering an adhesive sheet, wherein the steps from step to step are performed in a vacuum. 3. The wiring board according to claim 1, wherein the wiring board comprises a tape carrier.
3. The method for attaching an adhesive sheet according to claim 2, wherein the adhesive sheet is attached onto a wiring pattern of the tape carrier.