JPH08250532A - Manufacture of composite adhesive sheet - Google Patents

Abstract

PURPOSE: To increase an anti-package crack property and wettability by a method wherein heat-resistant adhesive varnish consisting of heat-resistant resin and polynadiimide is applied on a heat resistant film and then the film is heated and dried with a specified amount of residual solvent and extrusion length. CONSTITUTION: This composite sheet is an adhesive member to be used in manufacturing a semiconductor package by a method wherein a semiconductor chip is adhered to a lead frame with an adhesive and at least the semiconductor chip and adhered sections between the semiconductor chip and the lead frame are sealed with sealing material. Heat-resistant adhesive varnish which consists of heat-resistant resin and polynadiimide is applied on a heat-resistant film and then is dried with an amount of residual solvent 2% or below and a sticking-out length 1μm-2mm. The composite adhesive sheet manufactured by this method can increase the formability of a semiconductor package without deteriorating in an anti-package crack property at the time of solder reflow after the semiconductor package has absorbed moisture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite adhesive sheet as an adhesive member particularly suitable for adhering a semiconductor chip to a lead frame. In particular, the invention is
Manufacture of a composite adhesive sheet as an adhesive member using a heat-resistant adhesive having excellent package crack resistance during solder reflow after moisture absorption and good moldability in semiconductor packages, particularly LOC (Lead on Chip) structure packages Concerning the law.

[0002]

2. Description of the Related Art Conventionally, epoxy-based thermosetting adhesives and heat-resistant hot-melt adhesives have been used for connecting semiconductor lead frames and chips. In recent years, as the size of chips has increased, the percentage of chips in the package has increased. Therefore, when the adhesive or sealing material absorbs moisture, the absorbed moisture expands due to the heat during solder connection,
As a result, the phenomenon that cracks are generated in the package has frequently occurred. In order to prevent this phenomenon, it is possible to make the adhesive hard to flow at high temperature. However, if the adhesive is hard to flow, the package crack resistance is improved, but the wettability to the lead frame and the chip is deteriorated.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a composite adhesive sheet which is an adhesive member using a heat-resistant adhesive which is excellent in package crack resistance and also excellent in wettability to lead frames and chips. Is provided.

[0004]

According to the present invention, a semiconductor package is manufactured by adhering a semiconductor chip to a lead frame with an adhesive member and sealing at least the semiconductor chip and an adhesive portion between the semiconductor chip and the lead frame with a sealing material. Which is a composite sheet as an adhesive member for applying a heat-resistant adhesive varnish containing a heat-resistant resin and polynadiimide on a heat-resistant film, and the residual solvent amount is 2% or less, and the protrusion length is 1 μm to 2 mm. The present invention provides a method for producing a composite adhesive sheet, which comprises heating and drying so that

Among the specific adhesives used in the present invention, the heat resistant resin component has a glass transition temperature of 150 to 35.
It is preferably 0 ° C., a water absorption rate of 3% or less, and a protrusion length of 2 mm or less. There are no particular restrictions on the material, such as polyamide, polyimide, and other engineering plastics,
Polyamides and polyimides are preferred. Here, the polyimide includes a resin having an imide group such as polyamideimide, polyesterimide, and polyetherimide.

The glass transition temperature is preferably 170-30.
0 degreeC, More preferably, it is 200-290 degreeC. The protruding length, which represents the fluidity of the resin, is 2 mm or less, preferably 1
mm or less, more preferably 0.5 mm or less. When an adhesive film with a protruding length of 19 × 50 mm and a thickness of 25 μm is pressed under the conditions of 350 ° C., 3 MPa, and 1 minute, the protruding length of the adhesive is measured at the central portion in the long side direction, and the protruding amount Let it be the length. When the glass transition temperature is lower than 200 ° C. or when the protruding length is more than 1 mm, it is desirable that the water absorption rate is less than 1.5 wt%.

The heat-resistant resin component used in the present invention may be polyimide or polyamide alone, but preferably contains an amide group from the viewpoint of adhesive strength. The amide group is preferably 10 to 90 mol%, preferably 20 to 70 mol%, and more preferably 30 to 50 mol% of the total of the imide group and the amide group. If it is less than 10%, the adhesive strength is small, and 90%
The higher the amount, the higher the water absorption.

The heat-resistant resin component used in the present invention is synthesized from acid anhydride or dicarboxylic acid or its amide-forming derivative and diamine or diisocyanate. Examples of the diamine used in the present invention include paraphenylenediamine, metaphenylenediamine, metatoluylenediamine, 4,4′-diaminodiphenyl ether (DDE), 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 3,3 '
-Diaminodiphenyl sulfone, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone,
1,4-bis (4-aminocumyl) benzene (BA
P), 1,3-bis (4-aminocumyl) benzene,
1,3-bis (3-aminophenoxy) benzene, 1,
4-bis (3-aminophenoxy) benzene, 1,4-
Bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 2,2-bis [4- (3-aminophenoxy) phenyl] propane, bis [ 4- (3-aminophenoxy) phenyl] sulfone (m-APPS), bis [4- (4-aminophenoxy) phenyl] sulfone,
2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, and

A diamine represented by the general formula (1):

Examples thereof include siloxane diamines represented by the general formula (2) shown below.

[0009]

Embedded image [In Chemical Formula 1, Y represents an amino group or an isocyanate group, and R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms or an alkoxy group, out at least two is an alkyl or alkoxy group, X is -CH ₂ -, - C
_{(CH 3) 2 -, -} O -, - SO 2 -, - is a group represented by CO- or -NHCO-.

[0010]

Embedded image [In Chemical Formula 2, R ¹⁵ and R ¹⁸ are a divalent organic group, R ¹⁶
And R ¹⁷ are monovalent organic groups, and m is an integer of 1 to 100. ]

In the siloxanediamine represented by the general formula (2), R ¹⁵ and R ¹⁸ in the general formula (2) each independently include a trimethylene group, a tetramethylene group, a phenylene group, a toluylene group, and the like. R ¹⁶ and R ¹⁷ each independently include a methyl group, an ethyl group, a phenyl group, and the like, and a plurality of R ¹⁶ and a plurality of R ¹⁷ may be the same or different. In the general formula (2), when R ¹⁵ and R ¹⁸ are both trimethylene groups, and R ¹⁶ and R ¹⁷ are both methyl groups,
LP-7100 and X- are those for which m is 1, about 10 on average, about 20 on average, about 30 on average, about 50 on average, and about 100 on average, respectively.
22-161AS, X-22-161A, X-22-1
61B, X-22-161C and X-22-161E
(Both products are trade names of Shin-Etsu Chemical Co., Ltd.). Examples of the diisocyanate include diamines exemplified above in which an amino group is replaced with an isocyanate group.

As the acid anhydride, trimellitic anhydride,
Pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride (BTDA), 3,
3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2-bisphthalic acid hexafluoroisopropylidene dianhydride, bis (3,4-dicarboxyphenyl)
Ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride (DSDA), 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 2,2-bis [ 4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, ethylene glycol bistrimellitate dianhydride (EBTA),
Decamethylene glycol bis trimellitate dianhydride (DBTA), bisphenol A bis trimellitate dianhydride (BABT), 2,2-bis [4- (3,4-dicarboxyphenylbenzoyloxy) phenyl] hexafluoropropane di An anhydride, 4,4 ′-[1,4-phenylenebis (1-methylethylidene)] bisphenylbistrimellitate dianhydride and the like can be mentioned. Of these, trimellitic anhydride and DSDA are preferable.
As the dicarboxylic acid or its amide-forming derivative,
Terephthalic acid, isophthalic acid, biphenylcarboxylic acid,
There are phthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid and the like, and amide-forming derivatives of these dicarboxylic acids include dichloride and dialkyl ester of these dicarboxylic acids. Further, a part of the diamine or dicarboxylic acid may be replaced with an aminocarboxylic acid such as aminobenzoic acid.

From these diamines, acid anhydrides and dicarboxylic acids, the monomer may be appropriately selected so that the Tg of the resin obtained is 150 ° C. or higher. When polyimide and polyamide are mixed, the Tg of the adhesive after mixing may be 150 ° C. or higher. Polyimides are obtained by thermal or chemical ring closure of polyamic acids. The varnish used in the present invention does not necessarily have to be 100% imidized, but is preferably completely imidized.

The polynadiimide used in the present invention is N, N '-(4,4'-diphenylmethane).
Bisnadiimide, N, N '-(4,4'-diphenyloxy) bisnadiimide, N, N'-hexamethylenebisnadiimide, N, N'-m-benzylidenebisnadiimide, oligo (aniline-formaldehyde) resin polynadiimide, N , N ′-(4,4′-diphenylmethane) bisallylnadiimide, N, N′-hexamethylenebisallylnadiimide, N, N′-m-benzylidenebisallylnadiimide, etc. Used as a mixture of two or more species.

The mixing ratio of the heat resistant resin and the polynadiimide is appropriately determined according to the purpose, but it is preferable to use the polynadiimide in an amount of 5 to 180 parts by weight based on 100 parts by weight of the heat resistant resin. If the amount of polynadiimide is too small, the fluidity and curing will be insufficient, and if it is too large, the resin composition will become brittle. Especially when producing self-supporting films,
It is particularly preferable to use polynadiimide in a ratio of 100 parts by weight or less with respect to 100 parts by weight of the heat-resistant resin, from the viewpoint of sufficiently retaining flexibility.

The adhesive used in the present invention may be added with a curing accelerator for polynadiimide, an epoxy resin, a curing agent, a curing accelerator or the like. Further, a filler such as ceramic powder, glass powder, silver powder, copper powder or a coupling agent may be added.

The composite adhesive sheet of the present invention is obtained by applying a heat-resistant adhesive varnish containing a heat-resistant resin and polynadiimide to one or both sides of a surface-treated heat-resistant film, and then heating.

Examples of the heat-resistant film used in the present invention include polyimide, polyamide, and engineering plastics such as polysulfone, polyphenylene sulfide, polyether ether ketone, and polyarylate, which have a glass transition temperature (T
From the viewpoint of g), water absorption and thermal expansion coefficient, a polyimide film is preferable. Tg is 250 ° C or higher, water absorption is 2% or lower,
A film having a coefficient of thermal expansion of 3 × 10 -5 ° C -1 or less is particularly preferable.

The heat-resistant film needs a surface treatment in order to increase the adhesive force with the adhesive. As the surface treatment method, any treatment such as alkali treatment, chemical treatment such as silane coupling treatment, physical treatment such as sandblasting, plasma treatment, corona treatment, etc. can be used, but the most suitable treatment depends on the type of adhesive. Any suitable process may be used. Chemical treatments or plasma treatments are particularly suitable for the adhesives according to the invention.

The method for applying the heat resistant adhesive varnish to the heat resistant film is not particularly limited. It may be applied by any method such as a doctor blade, a knife coater or a die coater. Further, a film may be applied through the varnish, but it is not preferable because it is difficult to control the thickness. The film coated with the adhesive is heat-treated to remove the solvent and imidize, but the heating temperature differs depending on whether it is a polyamic acid varnish or a polyimide varnish. In the case of a polyamic acid varnish, a temperature of Tg or higher is required for imidization, but in the case of an imide varnish, it may be a temperature at which the solvent can be removed. The heating temperature varies depending on the solvent used, the type of the added polynadiimide, etc., but it is necessary to heat and dry so that the residual solvent amount is 2% or less and the protruding length is 1 μm to 2 mm. If the amount of the residual solvent is more than 2%, foaming occurs during sticking, which is not preferable. If the protrusion length is more than 2 mm, the package crack resistance is poor, and if it is less than 1 μm, the wetting becomes insufficient. The amount of residual solvent is 250 ° C for an adhesive single film with a thickness of 25 μm.
It is calculated from the weight loss before and after heating and drying for 30 minutes. To improve the adhesive strength between the adhesive and the heat resistant film, 2
It is preferable to perform heat treatment at a temperature of 50 ° C. or higher.

The composite adhesive sheet of the present invention is laminated on an adherend such as a lead frame, a ceramic plate, a metal plate, a metal foil, a plastic film, a plastic plate or a laminated plate, or
It is bonded by being sandwiched between adherends and heated and pressed at a temperature equal to or higher than the melting temperature of the adhesive.

[0022]

【Example】

Example 1 A four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, and a calcium chloride tube was charged with bis [4- (4-aminophenoxy) phenyl] sulfone (p-APPS) at 4.3.
2 g (10 mmol) and 23.7 g of N, N-dimethylformamide (DMF) were added and dissolved. Next, 5
Bis (3,4-dicarboxyphenyl) sulfone dianhydride (DSDA) 3.5 with cooling so as not to exceed ℃
8 g (10 mmol) was added little by little, and the mixture was allowed to react for 1 hour while cooling so as not to exceed 5 ° C. and then for 6 hours at room temperature to synthesize a polyamic acid. To the obtained polyamic acid varnish, 2.55 g of acetic anhydride and 1.98 g of pyridine were added and reacted at room temperature for 3 hours to synthesize a polyimide. The obtained polyimide varnish was poured into water, and the obtained precipitate was separated, pulverized and dried to obtain a polyimide powder. This polyimide powder was dissolved in DMF at a concentration of 0.1 g / dl, and the reduced viscosity when measured at 30 ° C. was 0.
It was 87 dl / g. This polyimide powder was dissolved in DMF, and the resulting varnish was cast on a glass plate. 10
After drying at 0 ° C for 10 minutes, peel it off, fix it on an iron frame, and set it to 250
A film was obtained by drying at 0 ° C. for 1 hour. Using the film thus obtained, by the penetration method,
With a load of 25 kg / cm ² and a heating rate of 10 ° C./min,
The glass transition temperature (Tg) of the polyimide was measured and found to be 270 ° C. The water absorption rate when the film was immersed in water at 25 ° C. for 24 hours was 2.3%. 19 x 5
0mm, 25μm thick adhesive film at 350 ℃, 3
The length of the protruding adhesive was measured at the center of the long side by pressing under a condition of MPa for 1 minute, and the protruding length was 0.01.
mm. 100 g of the above polyimide powder and N, N '
-NMP of 50 g of hexamethylenebisallylnadiimide
The varnish obtained by dissolving in 400 g was applied on a plasma-treated Upilex S film (polyimide film manufactured by Ube Industries, Ltd.), and then at 100 ° C. for 10 minutes, and further 2
It was dried at 75 ° C for 10 minutes to obtain a composite adhesive sheet. The protruding length of this composite adhesive sheet was 0.6 mm, and the residual solvent amount was 0.2%. When this composite adhesive sheet was used as an adhesive member and a semiconductor chip was attached to a lead frame as shown in FIG. 1 under the conditions of 375 ° C. and 3 MPa, the wetness of the adhesive to the lead frame and the chip was sufficient. In addition, after the package molded with the sealing material is subjected to moisture absorption treatment at 85 ° C. and 85% RH for 48 hours, 2
When solder reflow was performed in an infrared oven at 45 ° C., no crack was generated. In FIG. 1, 1 is an adhesive member, 2 is a semiconductor chip, 3 is a lead frame, 4 is a wire, and 5 is a sealing material.

Comparative Example 1 Example 1 was prepared using only the polyimide of Example 1 without adding N, N′-hexamethylenebisallylnadiimide.
A composite adhesive sheet was produced in the same manner as in. When this composite adhesive sheet was used as an adhesive member and adhered in the same manner as in Example 1, the wetness of the adhesive to the lead frame and the chips was insufficient. It should be noted that no crack was generated when solder reflow was performed on the molded package in the same manner as in Example 1 after sticking at 400 ° C.

Example 2 1.83 g of 4,4'-diamino-3,3 ', 5,5'-tetraisopropyldiphenylmethane (IPDDM)
(5 mmol), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) 2.05 g
(5 mmol) was dissolved in 30 g of NMP, 0.50 g (5 mmol) of triethylamine was added, and then trimellitic anhydride chloride 2.14 g was added while cooling to 5 ° C or lower.
(10 mmol) was added in small portions. After reacting at 5 ° C. or lower for 5 hours, acetic anhydride and pyridine were added to Example 1
Polyamideimide powder was obtained in the same manner as. This polyamideimide has a reduced viscosity of 0.57 dl / g and a Tg of 250 ° C.
Met. The water absorption was 1.0%, and the protruding length was 0.3 mm. Using 30 g of N, N '-(4,4'-diphenylmethane) bisallylnadiimide, 300
A composite adhesive sheet was produced in the same manner as in Example 1 except that it was dried at 0 ° C for 10 minutes. The protruding length of this composite adhesive sheet was 0.6 mm, and the residual solvent amount was 0.05%. Using this composite adhesive sheet as an adhesive member, a semiconductor chip was attached to a lead frame in the same manner as in Example 1, and the wetting of the adhesive was sufficient. When a package molded with a sealing material was subjected to solder reflow in the same manner as in Example 1, no crack was generated.

Example 3 Polyamideimide was obtained in the same manner as in Example 2 except that 3.69 g (9 mmol) of BAPP and 0.25 g (1 mmol) of LP-7100 were used as the diamine component. The reduced viscosity of this polyamide-imide is 0.80 dl.
/ G, Tg was 215 ℃. The water absorption rate is 1.5
%, The protrusion length was 0.4 mm. 100 g of the above polyamideimide powder and 30 g of N, N ′-(4,4′-diphenylmethane) bisallylnadimide were added to DMF4.
The varnish obtained by dissolving it in 00 g was coated on the Upilex S film treated with the silane coupling agent, and then 10
It was dried at 0 ° C. for 10 minutes and further at 275 ° C. for 10 minutes to obtain a composite adhesive sheet. The protruding length of this composite adhesive sheet was 1.0 mm, and the residual solvent amount was 0.15%. Using this composite adhesive sheet as an adhesive member, a semiconductor chip was attached to a lead frame in the same manner as in Example 1, and the wetting of the adhesive was sufficient. When a package molded with a sealing material was subjected to solder reflow in the same manner as in Example 1, no crack was generated.

Example 4 N, N'-m-benzylidene bisallylnadimide was used as 2
A composite adhesive sheet was obtained in the same manner as in Example 3 except that 0 g was used. The protruding length of this composite adhesive sheet is 0.7.
The residual solvent amount was 0.15% in mm. Using this composite adhesive sheet as an adhesive member, a semiconductor chip was attached to a lead frame in the same manner as in Example 1,
Wetting of the adhesive was sufficient. When a package molded with a sealing material was subjected to solder reflow in the same manner as in Example 1, no crack was generated.

[0027]

INDUSTRIAL APPLICABILITY The composite adhesive sheet of the present invention can improve the moldability without deteriorating the package crack resistance during solder reflow after moisture absorption of the semiconductor package.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor package.

[Explanation of symbols]

 1 Adhesive member 2 Semiconductor chip 3 Lead frame 4 Wire 5 Encapsulating material

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Claims (2)

[Claims] 1. A bonding member for manufacturing a semiconductor package by bonding a semiconductor chip to a lead frame with an adhesive member and sealing at least the semiconductor chip and a bonding portion between the semiconductor chip and the lead frame with a sealing material. A composite adhesive sheet, in which a heat-resistant adhesive varnish containing a heat-resistant resin and polynadiimide is applied on a heat-resistant film, and then dried by heating so that the residual solvent amount is 2% or less and the protruding length is 1 μm to 2 mm. A method for producing a composite adhesive sheet, comprising: 2. The heat-resistant resin has a glass transition temperature of 150 to 3
The method for producing a composite adhesive sheet according to claim 1, which is a heat-resistant resin having a water absorption of 3% or less at 50 ° C. and a protrusion length of 2 mm or less.