JPH02191366A - Resin-sealed type semiconductor device - Google Patents

Abstract

PURPOSE:To prevent any crack from being produced in a resin-sealed layer by applying a surface processing with a primer to a resin-sealed portion of a device construction member including a die pad rear surface and using a specific epoxy resin sealing material as a resin sealing material. CONSTITUTION:A primer processing 6 is applied to the entire surface of a semiconductor device construction member to be resin-sealed. Additionally, a low stress epoxy resin sealing material 5 is used as the resin sealing material, the low stress material is such that an elongation rate against tension at a room temperature (25 deg.C) is 0.7% or more, and it forms a 50mmphiX3mm thick disk sample, a further and absorption rate after it is left behind under 85 deg.C, 85% RH(relative humidity) conditions for 72 hours is less than 0.6weight%. Hereby, any crack is prevented from being produced in a resin-sealed layer which might be produced upon passage of the sample to a high temperature melted solder zone, to permit a satisfactory and effective assembly process to be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin-sealed semiconductor device that can be easily mounted on a printed circuit board.

Currently, resin-encapsulated diodes, transistors, ICs, LSIs, and VLSIs are the mainstream in the semiconductor industry, and demand for these is expected to increase further in the future. Devices are becoming increasingly integrated and chip sizes are increasing accordingly. On the other hand, it is desired that the external dimensions of the package be made smaller and thinner, and for this reason, semiconductor devices with small and thin packages are being manufactured using large chips.

When assembling such a semiconductor device with a large chip and a small thin package onto a wiring board, in order to easily and automatically connect the semiconductor device and the wiring board, the semiconductor device is immersed in a solder bath or exposed to high temperatures where the solder melts. A method of passing through zones is commonly employed.

However, if a resin-sealed semiconductor device with a large chip and a small, thin package is immersed in a solder bath or exposed to a high temperature zone where the solder melts, cracks may occur in the encapsulation resin layer due to thermal shock. , the reliability of the semiconductor device may be significantly impaired.

The occurrence of cracks in the sealing resin layer becomes noticeable when the sealing resin absorbs moisture, but in the actual work process, moisture absorption in the sealing resin layer is unavoidable. This occurrence has become a serious problem in actual assembly work processes.

The present invention was developed in view of the above circumstances, and even if a large chip is used to bridge a small, thin package and the package is immersed in a solder bath or exposed to a high temperature zone where the solder melts, the sealing resin layer will not crack. The purpose of the present invention is to provide a resin-sealed semiconductor device that does not cause problems.

In order to achieve the above object, the inventors of the present invention have conducted intensive studies and found that in a resin-sealed semiconductor device, at least the back surface of the die pad on which a silicon chip is mounted, preferably resin-sealed. Brimer treatment is applied to the entire surface of the semiconductor device component, and the resin is molded at room temperature (25°C) as a resin encapsulant.
) has a tensile elongation rate of 0.7% or more and 50IIW
A disk sample of Ilφx3+nnFJ was formed, and this was
By using a low-stress epoxy resin encapsulant whose moisture absorption rate is 0.6% by weight or less after being left at 85% RH (relative humidity) for 72 hours at a temperature of As a semiconductor device, it is a resin-sealed type that does not cause cracks in the sealing resin layer due to immersion in a solder bath or passing through a high-temperature zone where solder melts, and allows for a good and efficient assembly process. It was discovered that a semiconductor device could be obtained and the present invention was completed.

That is, the resin-sealed semiconductor device of the present invention is obtained by placing a silicon chip on a die pad, electrically connecting the silicon chip to a lead frame, and sealing these semiconductor device components with resin. In a semiconductor device, the back side of the die pad where the sealing resin is likely to peel off when immersed in a solder bath or passed through a high temperature zone where solder melts, preferably the resin-sealed part of the semiconductor device component. By applying brimer treatment to the entire surface of the part, the adhesive strength between the sealing resin and each of the above components is strengthened, and the tensile elongation rate at room 1fi (25°C) is 0.7% as a resin sealant. A low-stress epoxy resin with a moisture absorption rate of 0.6% by weight or less after being left at 85°C and 85% RH (relative humidity) for 7.2 hours in a sample formed into a disk shape of 50 wφ x 3-thick. By using this, when immersed in a solder bath or passed through a high temperature zone where solder melts, the sealing resin and each device component within the sealing resin,
In particular, the elongation of the encapsulant absorbs the shearing force that occurs at the interface between the encapsulant and these components due to the difference in expansion coefficient with the lead frame. The generation of a large amount of water vapor is also prevented due to its low hygroscopicity, and cracks in the sealing resin layer due to immersion in a solder bath or passage through a high temperature zone where solder melts are prevented as much as possible.

The present invention will be explained in more detail below.

The resin-sealed semiconductor device of the present invention is a semiconductor device in which a silicon chip is placed on a die pad, the silicon chip is electrically connected to a lead frame, and these semiconductor device components are sealed with resin. In this method, a brimer treatment is applied to the back surface of the die pad, preferably the entire surface of the resin-sealed portion of the device component, and a specific epoxy resin, which will be described later, is used as the resin sealant.

That is, the semiconductor device of the present invention includes a silicon chip, a die pad on which the silicon chip is placed, and a lead frame electrically connected to the silicon chip, and these are sealed with resin. Specifically, as shown in FIG. 1, such a semiconductor device includes a silicon chip 1 placed on a die pad 2,
and lead frames 3, 3 are connected via bonding wires 4.4, and these are sealed with resin 5, for example.

In the resin-sealed semiconductor device of the present invention, in the semiconductor device as shown in FIG.
Preferably a silicon chip 1. Primer treatment is applied to the entire portion of the die pad 2 and lead frame 3 to be sealed with resin. Specific examples of this primer treatment include, for example, as shown in FIG. 1, the primer treatment 6 is applied only to the back surface of the die pad 2, and as shown in FIG. As shown in FIG. 3, examples include applying primer treatment 6 to the silicon chip 1, die pad 2, and lead frames 3, 3, in which the entire surface of the parts that come in contact with the sealing resin 5 are subjected to primer treatment 6. .

Here, the primer used in the above primer treatment is not particularly limited, but includes a silane coupling agent,
In particular, those whose main component is a silane coupling agent containing one or more nitrogen atoms or epoxy groups in one molecule and which are diluted with various solvents are preferably used.

In this case, any silane coupling agent may be used as long as it has a functional group that can react with the sealing resin, but those represented by the following general formula % can be particularly preferably used. .

Here, X is at least one epoxy group, amino group,
Carboxyl group, hydroxyl group, ureido group.

an organic group having 15 or less carbon atoms having a maleimide group or a trialkoxysilyl group; R is an alkyl group;

A monovalent hydrocarbon group having 1 to 6 carbon atoms such as an alkenyl group or an aryl group; R' is an alkyl group or an alkenyl group;

A monovalent hydrocarbon group having 1 to 6 carbon atoms such as an aryl group, where n is 1
an integer of ~10, m is an integer of 1-3.

Examples of such silane coupling agents include those shown below.

NH, CiH, Si(QCHz)s.

NH2C,H,NHC,H,5i(OCH,)39HS
C,H,5L(OCR,),.

OH (CH,0), SiC, HGNHC2H4NHCH2
CHCH2QC,H,Si (QC)I, ), .

So-called NH1CNHC2H@5i(OCH3)3+(OH,O
), SiC,I(, NH*■.

These may be used alone or in combination of two or more, and may also be used in a partially hydrolyzed state.

When performing primer treatment not only on the back side of the die pad but also on the surface of the silicon chip with a primer containing these silane coupling agents as the main component, the halogen content in the silane coupling agent should be kept at 50 ppm or less, especially at 1.
It is preferable to set it to 0 ppm or less. When the surface of a silicon chip is coated with a primer made of a silane coupling agent with a halogen content of more than 50 PPL, the electrodes of the chip are likely to be corroded by the halogen.

Note that such a primer may contain an adhesion improver in order to improve the reaction adhesion of the sealing resin. Examples of the adhesion improver include titanium compounds such as titanium tetrabutoxide, titanium tetraisopropoxide, and titanium tetra-n-butoxide, and nitrogen compounds such as primary amines, secondary amines, tertiary amines, and cycloamidine derivatives. The blending amount of these adhesion improvers is 100 parts (parts by weight, hereinafter referred to as ``X'') of the silane coupling agent.
Preferably, 1 to 100 parts of O and O, particularly 1 to 80 parts of O and O, are used.

When performing the above primer treatment, it is difficult to control the amount of primer applied itself, so it is recommended to appropriately select the primer concentration of the solution and apply it uniformly by spray brushing, dipping, etc. to control the amount of application. Therefore, it is desirable to dilute the silane coupling agent and, if necessary, the adhesion improver with a solvent to preferably 10% by weight or less. In this case, the lower limit of the brimer concentration in the coating solution is set at a low concentration. Since the desired thickness can be formed by repeatedly applying the solution, there is no particular restriction, but since repeated applications are not efficient, it is desirable that the concentration of the primer be 0.5% by weight or more.The applied primer film. The thickness of the primer is preferably 10μ or less, especially 51m or less.The solvent for diluting the primer is selected as appropriate, taking into consideration the wettability and volatility of the base material (silicon chip, die pad, lead frame, etc.). 1 Usually, rubber alcohol, isopropyl alcohol, tetrahydrofuran, toluene, etc. are preferably used. Also, hexane, cyclohexane.

N-hebutane, methyl ethyl ketone, ethyl acetate, etc. can also be used as solvents.

After the semiconductor device of the present invention is subjected to the primer treatment, the tensile elongation rate at room temperature (25° C.) is 0.7% or more, preferably 0.8% or more, and the semiconductor device is formed into a disk shape of 5011Iφ×3m thick. The sample is sealed with a low stress epoxy resin whose moisture absorption rate is 0.6% by weight or less, preferably 0.5% by weight or less after being left at 85°C and 85% RH (relative humidity) for 72 hours. be. If the tensile elongation rate of the sealing resin is less than 0.7%, there will be a difference in expansion coefficient between the sealing resin and each semiconductor device component, especially the lead frame, when immersed in a solder bath or passed through a high temperature zone. The resin peels off due to the shearing force generated from the resin, and if the moisture absorption rate exceeds 0.6% by weight, cracks will occur in the resin due to water vapor accompanying the vaporization of a large amount of water in the resin when exposed to high temperatures. Here, the moisture absorption rate of the epoxy resin increases as the glass transition temperature increases. Therefore, in order to make the moisture absorption rate of the resin 0.6% by weight or less, the glass transition temperature needs to be 200° C. or less.

As such an epoxy resin sealing material, (A) epoxy resin Jf1. A composition containing (B) a novolac type phenolic resin as a curing agent, (C) stress reduction, (D) an inorganic filler, and (E) a curing accelerator is suitable.

Here, as long as the (A) epoxy resin is a compound having at least two epoxy groups in its molecule, there is no particular restriction on the molecular structure per molecular weight, etc., and it can include a wide range of commonly used resins. 0 For example, aromatic systems such as bisphenol type, alicyclic systems such as cyclohexane derivatives,
Further examples include epoxy novolak resins represented by the following general formula.

(In the formula, R1 is a hydrogen atom, a halogen atom, or a carbon number of 1 to
6, R1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 1 or more.) Epoxy compounds of triphenolmethane and polymers thereof can also be used. Note that these epoxy resins can be used alone or in a mixture of two or more.

CB) as a novolac type phenolic resin.

Examples include novolac type phenol resins obtained by reacting phenols such as phenol and alkylphenols with formaldehyde or paraformaldehyde, and modified resins thereof such as epoxidized or butylated novolac type phenol resins. The blending ratio of the novolac type phenolic resin is determined by the molar ratio ((a)/(b) of the epoxy group (a) of the epoxy resin (A) and the phenolic hydroxyl group (b) of the novolac type phenol resin (B)).
) is preferably in the range of 0.1 to 10.

If the molar ratio is less than 0.1 or more than 10, the moisture resistance, molding workability, and electrical properties of the cured product may deteriorate.

The stress reducing agent (C) improves the tensile elongation of the cured epoxy resin, and is a high molecular weight thermoplastic elastomer,
Fine silicone rubber powder, a block copolymer of aromatic polymer and silicone, etc. can be used. Here, as the high molecular weight thermoplastic elastomer, styrene-butadiene-methyl methacrylate copolymer (MBS), styrene-ethylene-butadiene-styrene copolymer (SE
US), organosiloxane-ethylene-propylene copolymer (SEP), and the like.

In addition, as a block copolymer of aromatic polymer and silicone, alkenyl group-containing epoxy resin or alkenyl group-containing phenol resin and the following formula % formula % (however, in the formula, H is a hydrogen atom, R is an organic group, and a is 0.00
1-0.1, b is 1.9-2.0.1.9<a + b
< 2, 2. In addition, the number of silicon atoms in one molecule is an integer from 20 to 1000, and the number of silicon atoms in one molecule is an integer of 20 to 1000.
The number of hydrogen atoms directly connected to the 4M atoms is an integer of 1 to 5.

) using the organopolysiloxane shown in

A reaction product obtained by addition reaction of these can be used.

The organic group in the above formula is preferably a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, and specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, etc. 1 to 10 alkyl groups, aryl groups with 6 to 1 carbon atoms such as phenyl groups and tolyl groups, alkoxy groups with 1 to 5 carbon atoms such as methoxy groups and ethoxy groups, and one or more of the above alkyl groups or aryl groups. in which the hydrogen atom of is substituted with a halogen atom or a trialkoxysilyl group, specifically CjlCH,-, CF2O,H,+, ClIC3H.

ci(to-C2H4S1(QC:H3)3゜-C,H,
5i(OCH,), -C,H,5i(OC,H,).

Examples include. In this case, the introduction rate of the alkoxy group can be 0 to 10 mol% in R of the above formula.

As the alkenyl group-containing epoxy resin or phenol resin to be reacted with the organopolysiloxane in 22, various epoxy resins or phenol resins having two or more alkenyl groups in one molecule can be used. Specific examples of the alkenyl group-containing epoxy resin include the following compounds.

(However, Pp q is usually an integer of 1<p<20.1≦q≦10.) These alkenyl group-containing epoxy resins can be obtained by normal synthesis methods. It can be easily obtained by epoxidizing with epichlorohydrin or by partially reacting various known epoxy resins with 2-allylphenol or the like.

The blending amount of the above component (C) is 1 1 of the epoxy resin of the component (A).
It is preferably 0 to 100 parts by weight, more preferably 1 to 100 parts by weight.

In addition, 5 (D) inorganic fillers include silica powder, alumina, antimony dioxide, talc, calcium carbonate,
Examples include titanium white, clay, asbestos, mica, red iron oxide, glass fiber, carbon fiber, etc., and silica powder and alumina are particularly preferred.The blending ratio of the inorganic filler is 25 to 90% by weight of the resin composition. Preferably, when the amount is less than 25% by weight, moisture resistance, heat resistance,
It has no effect on mechanical properties and moldability, and if it exceeds 90% by weight, the bulk becomes large and moldability is poor, which may make it unsuitable for practical use.

Furthermore, the curing accelerator (E) is used for the purpose of accelerating the reaction between the above-mentioned phenolic resin curing agent and the epoxy resin. As this curing accelerator, various substances generally used for curing epoxy compounds can be used, including imidazole, -2-methylimidazole, 2-ethylimidazole, 2,4-dimethyl Imidazole, 2-ethyl-4-methylimidazole.

2-undecylimidazole, 2-heptadecyl imidazole, 1-vinyl-2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2
-Imidazoles such as phenylimidazole and 2-phenyl-4-methylimidazole, triethylamine 5
Diethylenetriamine, triethylenetetramine, diethylaminopropylamine, N-aminoethylpiperazine, bis(4-amino-3-methylcyclohexyl)methane, metaxylyleneamine, menthanediamine.

3.9-bis(3-aminopropyl)-2,4,8゜1
0-tetraoxaspiro(5,5)undecane, 1.8
-Amine compounds such as diazabicyclo(5,4,0)undecene-7, complex compounds consisting of triethylamine and BF, organophosphine compounds such as triphenylphosphine, amine compounds and trimellitic anhydride, etc. Examples include adducts with m-anhydrides.

The amount of the curing accelerator to be used is not particularly limited, but a normal amount may be used.

These curing accelerators are not necessarily 1 when used.
The use of only one type of curing accelerator is not limited, and two or more types may be used in combination depending on the curing accelerating performance of the curing accelerator.

In addition, when sealing a semiconductor device with the above-mentioned composition, transfer molding, injection molding,
This can be done by a method such as a casting method. In this case, the molding temperature is 150-180℃, and the post-cure is 15℃.
It is preferable to carry out the reaction at 0 to 180°C for 2 to 16 hours.

The resin-sealed semiconductor device of the present invention is configured with a large chip in a small, thin package, and even if it is exposed to high temperatures, such as by immersing it in a solder bath or passing it through a high-temperature zone where solder melts, cracks occur in the sealing resin. QFPs with a die pad area of 25 mm or more and a resin thickness under the die pad of 1.5 mm or less
(quad flat package) and sop (small outline package).

mυ1 As explained above, the resin-sealed semiconductor device of the present invention is configured with a large chip in a small thin package, and even if it is immersed in a solder bath or exposed to a high temperature zone where the solder melts,
The sealing resin layer does not crack, and can be easily mounted on a printed circuit board.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 9. Comparative Examples 1 to 3] The silane coupling agent, adhesion improver shown in Table 1,
Primers (1) to (2) consisting of solvents were prepared. In Table 1, A to G indicate the following silane coupling agents. In addition, in the same table, TPT indicates 1,8-diazabicyclo(7,5,0)undecene-7, DBU indicates isopropyl alcohol, and IPA indicates isopropyl alcohol.

Silane coupling A, (CH,O), SiC,HllN HC,H4
NHCH, CH=CH.

B, (C,H,0)3SiC,H,NH.

C, (CH,O), 5iC3H, NHClH, NH.

D, (CH,O),5LCIH,+CH,NHC,H
,NH! E, (CH30)3SiC,H,NH, and 1
:1 (weight ratio) Using the above primers 1 to 1, 12 with the composition shown in Table 2.
Types of resin-sealed semiconductor device IF (package: 60
pin Q F P, size 20 wn x 14 cabinets.

411 fat thickness under die pad 0.7■, die pad size 1
0m10mX8, and 1 about these semiconductor devices.
After curing at 80°C for 4 hours, 85°C
/85% RH for 72 hours at constant temperature and humidity. This semiconductor device was immersed in a 260°C solder bath, and the occurrence of package crank was observed. The number of devices in which cracks occurred out of 10 was investigated. The results are shown in Table 2.

Also, with the same configuration, 14pin DIP* 20mX1
Forty semiconductor devices each having a diameter of 4 mm, a resin thickness under the die pad of 0.7 mm, and a die pad size of 10 mm x 8 mm were fabricated. These samples were left at 85° C. and 785% RH for 72 hours, and then immersed in a 260° C. solder bath for 10 seconds. These semiconductor devices were left in a pressure cooker at 120°C,
Corrosion of aluminum electrodes was measured. The results are also listed in Table 2.

Note that Table 3 shows the composition of the epoxy resin sealant used in the above-mentioned test.

Each component used in Table 3 is as follows.

Epoxy resin (■) Niortsu cresol novolac type epoxy resin (EOCN
1020, manufactured by Nippon Kayaku Co., Ltd.) Epoxy resin (■) Nitriphenolmethane type epoxy resin (EPPN501. Nippon Kayaku Co., Ltd. tS> Silicone modified phenol resin: Alkenyl group-containing phenol novolac resin (60 parts by weight) and the following formula CH, CH , CH.

A compound silicone-modified epoxy tree 1NCl with the following structure obtained by an addition reaction with a compound (40 parts by weight) represented by 11): Alkenyl group-containing phenol novolac type epoxy resin (65
A compound having the following structure obtained by the reaction of 40 parts by weight) with a compound represented by the following formula (40 parts by weight).

A compound having the following structure obtained by the reaction of the compound (35 parts by weight).

Thermoplastic tree JIIll (I): Styrene-butadiene-methacrylic methyl copolymer (
MBS) (Kane Ace B-56, Choku Chemical Co., Ltd. II) Thermoplastic resin 11tf (II): Styrene-ethylene-butadiene-styrene copolymer (
SEBS) (Toughtic Ml 913゜Asahi Kasei Ta> Brominated epoxy a1m: BREN (manufactured by Kuchimoto Kayakusha)

[Brief explanation of the drawing]

1 to 3 are cross-sectional views each showing a resin-sealed semiconductor device according to an embodiment of the present invention. 1... Silicon chip, 2... Die pad. 3... Lead frame, 4... Bonding wire, 5... Resin sealing material, 6... Primer treatment. Applicant: Shin-Etsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. Place the silicon chip on the die pad, electrically connect the silicon chip to the lead frame,
In a semiconductor device in which these semiconductor device components are sealed with resin, a part or all of the resin-sealed portion of the device component, including the back surface of the die pad or the back surface of the die pad, is surface-treated with a primer. , and the tensile elongation rate at 25°C is 0.7 as a resin sealant.
% or more, and which has a moisture absorption rate of 0.6% by weight or less after being left in an atmosphere of 85° C. and 85% relative humidity for 72 hours. Semiconductor equipment.