JPH1046114A - Low-stress filmy adhesive, and lead frame and semiconductor device obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-stress filmy adhesive in which stress hardly builds up during adhesion and which is useful for an adhesive member of a large-sized semiconductor chip. SOLUTION: A filmy adhesive (A) comprises an adhesive layer contg. 100 pts.wt. adhesive resin having a glass transition temperature of 50-250 deg.C and 10-400 pts.wt. elastic filler. Another filmy adhesive (B) comprises an adhesive layer contg. 100 pts.wt. adhesive resin having a glass transition temperature of 50-250 deg.C, 10-400 pts.wt. elastic filler, and 0-10 pts.wt. coupling agent. A still another filmy adhesive (C) is prepd. by incorporating 0.5-12 pts.wt. (based on 100 pts.wt. adhesive resin) solvent into the adhesive layer of filmy adhesive A or B. A multilayer filmy adhesive is prepd. by sticking a filmy adhesive selected among filmy adhesives A, B, and C to at least one side of a filmy substrate. These adhesives are used as bonding members for bonding lead frames to semiconductor chips.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a low-stress film adhesive used for an adhesive member of a semiconductor package, a lead frame using the same, and a semiconductor device. The film adhesive of the present invention is particularly suitably used for a semiconductor package using a large semiconductor chip.

[0002]

2. Description of the Related Art In a semiconductor package, a composite film in which an adhesive is applied to one or both sides of a film-like base material is formed by an L-type composite film.
For connection between a lead frame and a semiconductor chip in an OC (lead on chip) structure, COL (chip on lead) structure or frame tab structure, and for connection between an inner lead and a heat spreader in a composite lead frame with a heat sink. It is used as a joining member.

Conventionally, as an adhesive for joining a semiconductor lead frame and a semiconductor chip, a thermosetting adhesive such as an epoxy-based or rubber-modified epoxy-based adhesive, or a heat-resistant hot-melt adhesive such as polyimide or polyamideimide has been used. Is used.

[0004]

However, thermosetting adhesives such as epoxy-based and rubber-modified epoxy-based adhesives have excellent adhesive strength, but are inferior in heat resistance, and have a problem of contamination of semiconductor chips due to outgassing. is there. Heat-resistant hot-melt adhesives are attracting attention because they do not generate outgas and do not contaminate semiconductor chips. However, the bonding temperature for obtaining sufficient adhesive strength is high, and semiconductor chips are damaged or thermally degraded due to thermal stress. There is a problem. Further, with the increase in the size of the semiconductor chip, a problem of warpage of the lead frame or the semiconductor chip due to a temperature change at the time of bonding, and damage of the semiconductor chip due to the warp have also occurred. These problems are becoming more serious as the density of semiconductor packages increases and the size of semiconductor chips increases.

[0005] In recent years, with the increase in the density and thinning of semiconductor packages, package cracks (reflow cracks), which are thought to be caused by vaporization of moisture absorbed by the adhesive at the time of solder connection, have occurred frequently. It is a problem. Therefore, an adhesive that does not generate outgas, generates less stress, and does not cause reflow cracks is desired. The present invention solves such a problem, and provides a film-like adhesive which does not generate outgas, has low stress, and also has excellent reflow crack resistance, a lead frame and a semiconductor device using the same. is there.

[0006]

Means for Solving the Problems The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, have used a heat-resistant resin having a specific performance and made a predetermined amount of an elastic filler present in an adhesive. And found that a low stress adhesive was obtained, and completed the present invention. That is, the present invention
First, there is the following low-stress film adhesive. (A) A film adhesive comprising an adhesive resin having a glass transition temperature (Tg) of 50 to 250 ° C. and an adhesive layer containing 10 to 400 parts by weight of an elastic filler with respect to 100 parts by weight of the adhesive resin. (B) 100 parts by weight of an adhesive resin having a glass transition temperature (Tg) of 50 to 250 ° C., 10 to 400 parts by weight of an elastic filler,
And a film-like adhesive comprising an adhesive layer containing 0 to 10 parts by weight of a coupling agent. (C) The amount of the solvent present in the adhesive layer is
The film adhesive according to any one of the above (a) or (b), which is 0.5 to 12 parts by weight relative to 0 parts by weight.

The adhesive resin used here has a glass transition temperature (Tg) of 50 to 250 ° C., preferably 15 to 250 ° C.
Use the one of 0 to 230 ° C. Examples of such an adhesive resin include a heat-resistant thermoplastic resin or a heat-resistant adhesive resin containing the same as a main component. Examples of the heat-resistant thermoplastic resin include a polyimide resin and a polyamide resin.
Here, the polyimide resin includes a resin having an imide group such as polyamide imide, polyester imide, and polyether imide.

The elastic filler used in the present invention includes rubber particles such as acrylic rubber, butadiene rubber and silicone rubber. As the rubber particles, silicone rubber particles are preferable from the viewpoint of heat resistance, and particles having a core-shell structure or a surface treatment are particularly preferable from the viewpoints of adhesiveness and compatibility with an adhesive resin. The amount of the elastic filler is 10 to 400 parts by weight, preferably 40 to 300 parts by weight, based on 100 parts by weight of the adhesive resin. If it exceeds 400 parts by weight, the surface condition of the adhesive member deteriorates, and good adhesion cannot be obtained. If the amount is less than 10 parts by weight, the effect of reducing the stress is not sufficient. In addition, the amount of the solvent present (remaining) in the film-like adhesive was set at 0.1 with respect to 100 parts by weight of the adhesive resin.
It may be adjusted to be 5 to 12 parts by weight. This is because heat bonding can be performed at a relatively low temperature.

The production of the single-layer film adhesive of the present invention is carried out as follows. First, the adhesive resin is dissolved with an organic solvent. The organic solvent to be used is not particularly limited as long as it can uniformly dissolve the adhesive resin. For example,
Dimethyl sulfoxide, N-methylpyrrolidone, N, N
-Dimethylformamide, N, N-dimethylacetamide, tetrahydrofuran, dioxane, monoglyme,
Solvents such as diglyme, benzene, toluene, xylene, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, cellosolve acetate, butyl cellosolve acetate, cyclohexanone and butyl lactone are used. These may be a mixed solvent of two or more. To this, preferably, a coupling agent is added and mixed in an amount of 0 to 10 parts by weight based on 100 parts by weight of the adhesive resin. If the amount of the coupling agent exceeds 10 parts by weight, the wettability of the resulting film adhesive is poor, and the adhesive strength is also reduced.

As the coupling agent, silane coupling agents, that is, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxy Epoxy silanes such as silane, vinyltriethoxysilane, vinyltrimethoxysilane, vinylsilane such as γ-methacryloxymethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyl In addition to aminosilanes such as trimethoxysilane, mercaptosilanes such as γ-mercaptopropyltrimethoxysilane, and the like, there are also coupling agents such as titanates, aluminum chelates, and zircoaluminates. Good Epoxy silane coupling agents are particularly preferably used. If necessary, fillers such as resin particles, ceramic powder, glass powder, silver powder, and copper powder, and other additives can be added.

The obtained mixture (or mixture) is uniformly coated on a flat plate such as a glass plate or a stainless steel plate, or on a base film such as a polyester film (or sheet). The application method at this time is not particularly limited. For example, it can be applied by a method using a doctor blade, a knife coater, a die coater or the like. After the application, it is heated and dried, then cooled to room temperature, and then peeled off from a flat plate or a base film to obtain a single-layer film adhesive. Here, the heating and drying conditions differ depending on whether the adhesive resin varnish is a polyamide acid varnish or a polyimide varnish. When the adhesive resin varnish is a polyamide acid varnish, Tg is used to imidize the resin.
The above temperature is required. In the case of a polyimide varnish, any temperature may be used as long as the solvent can be evaporated and volatilized. Further, by changing the conditions of heating and drying, the amount of the residual solvent in the adhesive can be adjusted.

As another manufacturing method, a film-like (or sheet-like) gas-permeable cloth such as glass cloth, carbon fiber cloth, or polyaramid cloth is impregnated with the mixture (or mixture), and the mixture is heated and dried. There are ways. The resulting tape is also called a composite adhesive tape, but in the present invention, it is used in the sense that it is included in a single-layer film adhesive.

The present invention also provides (d) a film-like substrate on at least one side of which (a)
It is also a multi-layer (the base material is counted as one layer) film adhesive in contact with any one of the film adhesives of (c) to (c). Here, examples of the substrate used include heat-resistant films of engineering plastics such as polyimide, polyamide, polysulfone, polyphenylene sulfide, polyetheretherketone, and polyarylate, and metal foils such as copper foil, aluminum foil, and stainless steel foil. .

The heat-resistant film is made of Tg of an adhesive resin.
Films with higher Tg are used. It may be appropriately selected according to the Tg of the adhesive resin to be used.
Those having a temperature of 00 ° C or higher, preferably 250 ° C or higher are used. Further, it is more preferable that the heat-resistant film has a water absorption of 2% by weight or less and a coefficient of thermal expansion of 3 × 10 ⁻⁵ / ° C. or less. One of the heat-resistant films satisfying such characteristics is a polyimide film.

The heat-resistant film is preferably subjected to a surface treatment in order to increase the adhesiveness with the adhesive resin. As the surface treatment method, any treatment such as chemical treatment such as alkali treatment and silane coupling treatment, physical treatment such as sandblasting, plasma treatment, corona treatment and the like can be used. The most suitable treatment may be used according to the type of the adhesive resin, but a chemical treatment or a plasma treatment is particularly suitable.

The production of the multilayer film adhesive of the present invention is carried out as follows. First, the adhesive resin is dissolved with an organic solvent. The organic solvent to be used is not particularly limited as long as it can uniformly dissolve the adhesive resin as in the production of the single-layer film adhesive. One or a mixture of two or more of the above-mentioned organic solvents can be used. An elastic filler (adhesive resin 100
Add 10-400 parts by weight (based on parts by weight) and mix. As the elastic filler, the above-mentioned acrylic rubber,
There are rubber particles such as butadiene rubber and silicone rubber.

In addition, preferably, a coupling agent 0
Add 〜１０10 parts by weight. The coupling agent is the same as described above. If necessary, fillers such as resin particles, ceramic powder, glass powder, silver powder, and copper powder, and other additives can be added and mixed. The resulting mixture (or mixture) is uniformly applied to one or both surfaces of a heat-resistant film such as the above-mentioned polyimide or a metal foil such as a copper foil. As described above, for example, the coating can be performed by a doctor blade, a knife coater, a die coater, or the like. It can also be performed by passing a base material (heat-resistant film or metal foil) through a varnish solution, but it is difficult to control the thickness of the adhesive resin. After application, heating and drying, and then cooling to room temperature, a multi-layer film adhesive is obtained. The heating and drying conditions are the same as those for the single-layer film adhesive. When the heat-resistant adhesive varnish is applied to both sides of the substrate, the heat-resistant adhesive applied to both sides may be the same or different.

The present invention further provides: (e) a lead frame to which the single-layer film adhesive or the multilayer film adhesive is adhered; (f) a lead frame and a semiconductor chip are directly connected to the lead frame. (A) a semiconductor device bonded with any one of the film adhesives of (a) to (d); and
(D) through a die bonding material other than (d)
(D) a semiconductor device bonded with the film adhesive; That is, a semiconductor device having excellent reliability can be manufactured using the single-layer film adhesive or the multilayer film adhesive of the present invention. For example, in one method, the film adhesive of the present invention is punched into a predetermined size, and the obtained film piece is sandwiched between a lead frame and a semiconductor chip.
Pressure bonding is performed at 0.1 to 10 MPa for 0.1 to 10 seconds, and then the lead frame and the semiconductor chip are joined with a gold wire or the like, and the semiconductor device is manufactured by transfer molding with a molding material such as epoxy resin and sealing. (Figure 1). Another method is to press-bond a film-shaped adhesive piece of the present invention punched into a predetermined size to a lead frame, and then place a semiconductor chip on the pressure-bonded piece, and then bond the lead frame and the semiconductor chip. The semiconductor device can be manufactured by bonding with a gold wire or the like and sealing with a molding material such as an epoxy resin (FIG. 2). In another method, a piece of the film adhesive of the present invention punched into a predetermined size is pressure-bonded to a lead frame, and then a die bond other than the film adhesive of the present invention is bonded to a predetermined portion of the film adhesive. A material (silver paste, die bond film, etc.) is placed, a semiconductor chip is placed on this, and pressure bonding is performed. Thereafter, the lead frame and the semiconductor chip are joined with a gold wire or the like, and sealed with a molding material such as an epoxy resin. A semiconductor device can also be manufactured (FIG. 3). FIG. 1 is a schematic cross-sectional view of a semiconductor package having a LOC structure, FIG. 2 is a schematic cross-sectional view of a semiconductor package with a heat spreader in which a film-like adhesive of the present invention and a semiconductor chip are directly bonded, and FIG. FIG. 1 is a schematic cross-sectional view of a semiconductor package with a heat spreader in which a film adhesive of the present invention and a semiconductor chip are bonded through a die bonding material.

[0019]

The present invention will be specifically described below with reference to examples. Example 1 Trimellitic anhydride monochloride / 2,2-bis [4- (4-aminophenoxy) phenyl] propane /
1,12-diaminododecane / 1,3-bis (3-aminopropyl) tetramethylsiloxane = 100/75 /
100 g of a 20/5 (molar ratio) polyamideimide resin having a Tg of 190 ° C., 5 g of γ-glycidoxypropyltrimethoxysilane (hereinafter abbreviated as CPL) and 40 g of a silicone rubber filler are mixed with 300 g of N, N-dimethylformamide (DMF). To prepare a varnish. This varnish is applied on both sides of a polyimide film having a thickness of 50 μm so that the thickness after drying is 25 μm, and dried at 170 ° C. for 10 minutes, and a three-layer film adhesive (adhesive tape) having a thickness of 100 μm. Was prepared. The amount of the residual solvent in the adhesive layer of the adhesive tape was 4.8% by weight (5.0 parts by weight based on 100 parts by weight of the polyamideimide resin). This adhesive tape is applied to a copper plate at 300 ° C. or 250 ° C., 3 MPa,
The film was attached under the condition of 3 s and the peel strength (peel) at 90 degrees was measured. As a result, it was 1.2 kg / cm and 0.8 kg / cm, respectively. When a 40 mm × 8 mm adhesive tape was stuck to a 45 mm × 10 mm × 150 μm 42 alloy plate at 300 ° C., 3 MPa, and 3 s, the amount of warpage at the center was 600 μm. After attaching this tape to a copper lead frame, a semiconductor chip was adhered. There was no problem when wire bonding was performed using a gold wire. The LOC package shown in FIG. 1 was fabricated by molding with a sealing material. 168 hours at 85 ° C and 85% relative humidity
After moisture absorption, reflow was performed in an IR furnace at Max 245 ° C., and no crack was generated. The amount of the residual solvent in the adhesive layer of the adhesive tape was 30 minutes at 300 ° C.
After drying, the weight change before and after drying was measured, and the weight of the polyimide film (substrate) was corrected and calculated.

Example 2 The varnish of Example 1 was applied to a polyester film so as to have a thickness of 40 μm after drying, dried at 100 ° C. for 10 minutes, peeled off and fixed in a metal frame, and dried at 180 ° C. for 10 minutes. After drying for a minute, a single-layer film adhesive (adhesive tape) was produced. The amount of residual solvent in the adhesive layer of this adhesive tape was 3.9.
% By weight (4.1 parts by weight based on 100 parts by weight of the polyamideimide resin). Apply this adhesive tape to a copper plate for 30
It was attached at 0 ° C. or 250 ° C. under the conditions of 3 MPa and 3 s, and the 90 ° peel strength (peel) was measured. As a result, it was 1.1 kg / cm and 0.7 kg / cm, respectively. The amount of warpage measured in the same manner as in Example 1 was 45.
It was 0 μm. After attaching this adhesive tape to a copper lead frame, a semiconductor chip was attached. There was no problem when wire bonding was performed using a gold wire. The LOC package shown in FIG. 1 was fabricated by molding with a sealing material. 8
After absorbing 168 h at 5 ° C. and a relative humidity of 85%,
When reflow was performed in an IR furnace at Max 245 ° C., no crack was generated.

Example 3 The same varnish as in Example 1 was applied to one side of a 105 μm-thick roughened copper foil having a thickness of 105 μm, except that the amount of the silicone rubber filler was changed to 65 g, so that the thickness after drying became 20 μm. Work, 1
Copper foil with adhesive after drying at 60 ° C for 10 minutes (adhesive tape)
Was prepared. The amount of the residual solvent in the adhesive layer of this adhesive tape was 5.5% by weight (5.8 parts by weight based on 100 parts by weight of the polyamideimide resin). When this adhesive tape was attached to a copper plate at 300 ° C. or 250 ° C. under the conditions of 3 MPa and 3 s, and the peel strength (peel) was measured at 90 °, it was 1.4 kg / cm and 1.0 kg / cm, respectively. . After attaching this adhesive tape to a copper lead frame, the semiconductor chip was adhered to the adhesive surface using a silver paste. No warpage was observed when pasted on the lead frame. There was no problem when wire bonding was performed using a gold wire. A package with a heat spreader shown in FIG. 3 was produced by molding with a sealing material. After absorbing 168 h at 85 ° C. and a relative humidity of 85%, Max 245 ° C.
When the reflow was performed in the IR furnace, no crack was generated.

Example 4 Trimellitic anhydride monochloride / 2,2-bis [4- (4-aminophenoxy) phenyl] propane /
Tg22 consisting of 1,3-bis (3-aminopropyl) tetramethylsiloxane = 100/95/5 (molar ratio)
A varnish was prepared by dissolving 100 g of a polyamideimide resin at 5 ° C. and 140 g of a silicone rubber filler in 300 g of N-methylpyrrolidone. Using this varnish, a single-layer adhesive tape was produced in the same manner as in Example 2. The amount of the residual solvent in the adhesive layer of the adhesive tape was 4.2% by weight (4.4 parts by weight based on 100 parts by weight of the polyamideimide resin). This adhesive tape on a copper plate at 300 ° C or 250 ° C,
It was pasted under the conditions of 3 MPa and 3 s, and the 90 degree peeling strength (peel) was measured.
cm and 0.6 kg / cm. The warpage measured in the same manner as in Example 1 was 200 μm. After attaching this adhesive tape to a copper lead frame, a semiconductor chip was attached. There was no problem when wire bonding was performed using a gold wire. The LOC package shown in FIG. 1 was fabricated by molding with a sealing material. 85 ° C, 85% relative humidity
After 168 h of moisture absorption under the conditions of Max.
When reflow was performed in the furnace, no crack was generated.

Comparative Example 1 Trimellitic anhydride monochloride / 2,2-bis [4- (4-aminophenoxy) phenyl] propane / 1,3-bis (3-aminopropyl) tetramethylsiloxane = 100 / 95/5
A varnish was prepared by dissolving 100 g of a polyamideimide resin having a Tg of 225 ° C. (molar ratio) in 300 g of N-methylpyrrolidone. Using this varnish, a three-layer adhesive tape was produced in the same manner as in Example 1. The residual solvent amount in the adhesive layer of this adhesive tape was 4.5% by weight (4.7 parts by weight based on 100 parts by weight of the polyamideimide resin). The amount of warpage was 1200 μm. When this adhesive tape was adhered to a copper plate at 300 ° C. or 250 ° C. under the conditions of 3 MPa and 3 s and the peel strength (peel) was measured at 90 °, it was 1.1 kg / cm and 0.7 k, respectively.
g / cm. When this adhesive tape was attached to a copper lead frame, the warpage was large, and an attempt was made to attach a semiconductor chip. However, the end of the adhesive tape did not adhere well.

Example 5 Trimellitic anhydride monochloride / 2,2-bis [4- (4-aminophenoxy) phenyl] propane /
1,3-bis (3-aminopropyl) tetramethylsiloxane = 100/70/30 (molar ratio), 100 g of a polyamideimide resin having a Tg of 180 ° C. and 65 g of a silicone rubber filler were dissolved in 300 g of N-methylpyrrolidone, A varnish was prepared. Using this varnish, a copper foil with adhesive (adhesive tape) was produced in the same manner as in Example 3. The amount of residual solvent in the adhesive layer of this adhesive tape was 5.2.
% By weight (5.5 parts by weight with respect to 100 parts by weight of the polyamideimide resin). Apply this adhesive tape to a copper plate for 30
The film was attached at 0 ° C. or 250 ° C. under the conditions of 3 MPa and 3 s, and the peel strength (peel) measured at 90 ° was 1.5 kg / cm and 1.1 kg / cm, respectively. After attaching this adhesive tape to a copper lead frame, a semiconductor chip was attached. No warpage was observed when affixed to the lead frame. There was no problem when wire bonding was performed using a gold wire. A semiconductor package with a heat spreader shown in FIG. 2 was fabricated by molding with a sealing material. 168 at 85 ° C and 85% relative humidity
After moisture absorption, reflow was performed in an IR furnace at Max 245 ° C., and no crack was generated.

[0025]

The film adhesive of the present invention has a small stress generated during bonding. Therefore, it is useful as an adhesive member for a large semiconductor chip. Further, a semiconductor device using the film adhesive of the present invention has high reliability.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a semiconductor package having a LOC structure.

FIG. 2 is a schematic cross-sectional view of a semiconductor package with a heat spreader.

FIG. 3 is a schematic cross-sectional view of a semiconductor package with a heat spreader in which a semiconductor chip and a lead frame are bonded via a die bond material.

[Description of Signs] 1 ... Film adhesive 1a ... Adhesive layer 1b ... Heat spreader 2 ... Semiconductor chip 3 ... Lead frame 4 ... Wire 5 ... Sealant 6 ... Die bond material

Claims (7)

[Claims] 1. A film adhesive comprising an adhesive resin having a glass transition temperature (Tg) of 50 to 250 ° C. and an adhesive layer containing 10 to 400 parts by weight of an elastic filler with respect to 100 parts by weight of the adhesive resin. 2. A film-like adhesive comprising an adhesive layer containing 100 parts by weight of an adhesive resin having a glass transition temperature (Tg) of 50 to 250 ° C., 10 to 400 parts by weight of an elastic filler, and 0 to 10 parts by weight of a coupling agent. Agent. 3. The film adhesive according to claim 1, wherein the amount of the solvent present in the adhesive layer is 0.5 to 12 parts by weight based on 100 parts by weight of the adhesive resin. 4. A multilayer film adhesive comprising the film substrate according to claim 1 and at least one surface of the film substrate. 5. A lead frame to which the film adhesive according to claim 1 is adhered. 6. A semiconductor device in which a lead frame and a semiconductor chip are directly adhered with the film adhesive according to claim 1. 7. A semiconductor device in which a lead frame and a semiconductor chip are adhered to each other with a film-like adhesive according to any one of claims 1 to 4 via a die-bonding material other than those described in claim 1.