JPH05175262A - Resin sealing semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the crack resistance during the reflow time after moisture absorption of a thin surface mounted semiconductor device resin-sealed with Si chip in large size. CONSTITUTION:In the surface mounted semiconductor device, the glass transfer point Tg is set lower than 140 deg.C or higher than 220 deg.C and the Si chip area sealed with a sealing material comprising an epoxy base or polyimide base, respectively, when Tg is lower than 140 deg.C or higher than 220 deg.C is set wider than 25mm<2> and the package thickness is set thinner than 3mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mount type resin-encapsulated semiconductor device having a large Si chip and a thin package.

[0002]

2. Description of the Related Art Conventionally, a resin-encapsulated semiconductor device that has been developed to be called rice in the industry has a glass transition point Tg of 150 to 180 ° C. after molding and curing, and a natural crystalline silica powder as an inorganic filler. Alternatively, an epoxy resin encapsulant containing 50 to 65 vol% of fused silica powder or a mixture of these fillers is used all over the world. The package form is DIP, SIP, ZIP, TO-92, TO-22
0, TO-3P, TO-126, SOT-23, etc. When Tg is lowered to 150 ° C. or lower, 150 to −55
In a thermal shock test of ℃ (or -65 ℃), there is a problem that elongation at Tg or more causes the Au wire to be broken and the reliability is significantly impaired. To prevent this problem, Tg is set to 15
It has been used while controlling at 0 to 180 ° C.

[0003]

In the resin-encapsulated semiconductor device, the size of the Si chip has become larger and the package has become thinner in recent years. On the other hand, the soldering work for mounting these resin-encapsulated semiconductor devices on a printed wiring board (PCB) is changing from the conventional pin insertion to planar mounting called surface mounting. When a conventional epoxy resin encapsulant is used in a thin package that mounts a large Si chip and this resin-encapsulated semiconductor device is surface-mounted, it absorbs a very slight amount of moisture under natural conditions. However, if this is exposed to a reflow temperature of 200 ° C to 300 ° C where soldering is performed suddenly, a very small amount of water present inside the package is suddenly gasified and becomes an internal pressure, which causes the internal stress to be surrounded. If the breaking strength of the resin layer is exceeded, the resin layer will be easily cracked and the reliability will be significantly impaired. The present invention has been made in view of such circumstances, and an object thereof is to greatly improve the crack resistance during reflow after humidification in a thin resin-sealed semiconductor device mounted with a large Si chip.

[0004]

That is, the present invention is based on Si
In a thin surface-mounting resin-sealed semiconductor device having a chip area of 25 mm ² or more or a side length of 5 mm or more and a package thickness of 3 mm or less, an inorganic filler is used in an amount of 65 to 90.
The present invention relates to a semiconductor device characterized by being molded and encapsulated with a thermosetting resin encapsulant having a glass transition point Tg of vol% of 140 ° C. or lower or 220 ° C. or higher. The area of the Si chip is 25 mm ² or more, or the length of one side is 5 mm or more,
Measures to improve the crack resistance during reflow after humidifying a thin resin-sealed semiconductor device with a package thickness of 3 mm or less are as follows: (1) Breaking strength at high temperature at reflow temperature of 215 to 260 ° C. Augmentation. (2) Reduction of moisture absorption rate (3)
The adhesive strength between the insert such as Si chip and lead frame metal (CuorFe type) and the sealing material can be increased.

Of the above, the high temperature strength enhancement has a Tg of 15
In the conventional epoxy-based encapsulant of 0 to 180 ° C, it means that the strength in the rubber-like region must be increased,
This major enhancement is essentially impossible. Significant enhancement of high temperature strength is possible only by increasing Tg.
However, the relationship between Tg and high-temperature strength has not been clarified so far, and it has not been possible to predict what temperature Tg should be raised to. On the other hand, it is necessary to change the resin system of the raw material in order to greatly increase or decrease Tg. Therefore,
For various epoxy resin and polyimide resin encapsulants,
Tg, high temperature strength, moisture absorption, adhesion and QFP54 pin
Package: 20 x 14 x 2 mmt, Si chip size:
The 6 × 6 mmt lead frame: 42 Alloy was examined in detail for crack resistance during reflow after absorbing moisture. Table 1 shows the skeleton of the basic resin of the resin-based sealing material used.

[0006]

[Table 1]

(1) High temperature strength The relationship between Tg and high temperature bending strength is shown in FIG. The high temperature bending strength strongly depends on Tg, and if Tg is increased, the high temperature strength can be enhanced as expected. It was a remarkable finding that the polyimide system was found to be continuous on the extension line of the epoxy system. This relationship also applies to the relationship between the following Tg, moisture absorption rate, and adhesiveness. It is clear from FIGS. 2, 3 and 4 that the high temperature bending strength is governed by the same temperature bending elastic modulus (hardness). (2) Moisture absorption rate The relationship between Tg and hygroscopicity is shown in FIG. The hygroscopicity also depends on Tg, and when Tg is increased, the hygroscopicity tends to increase,
On the contrary, it is understood that it is necessary to lower Tg in order to lower the hygroscopicity. (3) Adhesiveness The relationship between Tg and adhesiveness is shown in FIG. The adhesiveness also depends on Tg, and when Tg is increased, the adhesiveness tends to decrease.
It was found that the adhesiveness can be greatly enhanced by lowering g. (4) Crack resistance during reflow after moisture absorption of package The QFP54pin is moisture-absorbed at 85 ° C. and 85% RH, taken out appropriately, and subjected to heat treatment at reflow conditions of 215 ° C. and 90 ° C. until the package cracks.
FIG. 7 is a graph in which the moisture absorption time at 85 ° C. and 85% RH was obtained and the relationship between the moisture absorption time and Tg was plotted. Tg of 220 ° C or higher
It was found that when g was 140 ° C. or less, it was differentiated into two poles, and after moisture absorption, crack resistance during reflow could be improved (extension of moisture absorption time until crack generation). The former having a high Tg is a polyimide-based encapsulating material, and it is advantageous that it has high high-temperature strength. The latter, which has a low Tg, is an epoxy-based encapsulant, and is effective in low hygroscopicity and high adhesion. Examples of the polyimide-based resin used in the present invention include bismaleimide-based resins and maleic anhydride-aromatic diamine direct addition reaction-based resins, and epoxy-based resins include bisphenol A type epoxy resins, biphenyl type epoxy resins, There are resorcinol glycidyl ether type epoxy resins and the like. Further, as the curing agent, phenol novolac resin, phenol aralkyl resin, etc. can be used.

Conventionally, since the upper limit temperature of the reliability test of the resin-encapsulated semiconductor device is 150 ° C., it has been standard to set Tg, which is an index of heat resistance, to 150 ° C. or higher to 180 ° C. As described above, when the Tg of the sealing material is 150 ° C. or lower, the elongation in the rubber-like region above Tg cannot be ignored, and the Au wire is broken in the temperature cycle test of 150 to −55 (or −65) ° C. There was a problem that it was easy to lose reliability. However, this thermal shock resistance increases the content of fillers and fused silica that do not diffuse, adsorb, or permeate moisture,
It can be compensated by lowering the coefficient of linear expansion. Increasing the content of fused silica is also effective in increasing the high temperature strength by reducing elasticity and increasing elasticity at high temperatures. Therefore,
Fused silica powder content of fused silica in highly filled epoxy type encapsulant and moisture absorption characteristics (85 ℃, 85% RH), linear expansion coefficient, high temperature bending strength, and QFP54 pin package and 65 ℃, 95% Table 2 shows the state of crack generation when exposed to 215 ° C. and 90 ° C. heat treatment conditions for reflow after absorbing moisture for RH for 72 hours.

[0009]

[Table 2] (Note) *: QFP54pin 20 x 14 x 2 mmt L / F: 42 alloy, chip: 6 x 6 mm 65 ° C 95% RH72h + VPS (215 ° C 90 sec)

As the content of the fused silica powder is increased, the high temperature strength is enhanced together with the improvement of the moisture absorption characteristics such as the reduction of the moisture absorption rate, and the linear expansion coefficient is also reduced, so that the crack resistance during reflow is greatly increased. It was found to improve. Reduction of linear expansion is 150 to -55 (or -6 when Tg is low).
5) It is also extremely effective for preventing Au wire disconnection during temperature cycling at ° C. Next, the shape of fused silica and QFP54pi
Moisture absorption time for crack generation during reflow of n h (85 ℃, 85
% RH), and spiral flow SF (180 ° C, 7
The relationship of 0 kg / cm ² ) is shown in FIGS. Regarding the shape of the fused silica powder, the angular shape is more advantageous than the spherical shape in terms of crack resistance during reflow. However, if the amount of the horny powder is increased, the fluidity is impaired. Therefore, in order to achieve both the fluidity and the crack resistance during reflow, it is preferable to appropriately adjust the horny powder and the spherical powder. In addition to the above resin components and fillers, brominated epoxy resins, flame retardants such as antimony trioxide, and the like can be added as necessary as components that can be added to the encapsulating material in the present invention. The molding conditions for the encapsulant according to the present invention are 165 to 165 in the case of an epoxy resin.
190 ° C, 170 to 20 for polyimide resin
It can be arbitrarily selected from 0 ° C. and 50 to 200. Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

[0011]

EXAMPLES Example 1 Tg composed of main raw materials having the chemical structure shown in Table 1
2 to 4, 5 and 6 show the relationship between Tg and high temperature bending property, moisture absorption rate, and adhesiveness for various epoxy type encapsulants and polyimide type encapsulants different from each other. Also, using various epoxy type encapsulants and polyimide encapsulants with different Tg, QFP54 pin package (20 x 14 x
2.0 mmt, Si chip size: 6 x 6 mm, lead frame: 42 Alloy) is molded and cured under normal conditions, and this is taken out at 85 ° C and 85% RH for moisture absorption, and immediately reflowed at 215 ° C for heat treatment. The presence or absence of package cracks was observed when exposed for 90 seconds (Florinert: FC-70, saturated vapor layer at boiling point manufactured by Sumitomo 3M). And, until this crack occurs 8
The moisture absorption time at 5 ° C. and 85% RH was determined. FIG. 7 shows the relationship between this reflow cracking moisture absorption time and Tg.

Example 2 (1) Bisphenol A type epoxy (equivalent 500) 80 (parts by weight) (2) Phenol novolac (equivalent 107) 25 (parts by weight) (3) 1,8-diazabicyclo (5,4,0) ) Undecene-7 3 (parts by weight) (4) Fused silica powder spherical (average particle size 15 μm, maximum particle size 100 μm) 257 (32.5 vol%) (5) Fused silica powder angular (average particle size 15 μm, maximum particle size 100 μm) 257 (32.5vol%) (6) 3-glycidoxypropyltrimethoxysilane 3 (parts by weight) (7) carnauba wax 3 (parts by weight) (8) novolac type brominated epoxy resin (equivalent weight 275) 20 (parts by weight) Parts) (9) antimony trioxide 15 (parts by weight) (10) carbon black (average particle size 200 mμm) 2 (parts by weight) The above (1) to (10) are put on a mixing roll to form 90
The mixture was kneaded at 10 ° C. for 10 minutes, cooled, and then pulverized to obtain an epoxy encapsulant. A 4 × 4 × 20 mm rod-shaped test piece of 175 ° C.
Transfer molding at 70kg / cm ² , 90sec, 175
As a result of obtaining the glass transition temperature Tg, the temperature at the intersection of the two gradients with different gradients was determined by performing elongation at 5 ° C / min for 5 hours at 5 ° C / min.
The linear expansion coefficient α ₁ between 05 ℃ and room temperature and Tg is 1.4 × 1
It was 0 ^-5 ° C ^-1 . On the other hand, similar to the first embodiment, QFP
The moisture absorption time (85 ° C., 85% RH) at which reflow cracks occurred in the 54-pin package was determined to be 84 hours, which was good.

Example 3 (1) 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl, biphenyl (equivalent weight 195) 80 (parts by weight) (2) Phenol aralkyl resin represented by the following general formula (equivalent 175) 84 (parts by weight)

[Chemical 1] (3) 1,8-diazabicyclo (5,4,0) undecene-7 3 (parts by weight) (4) fused silica powder spherical (average particle size 15 μm, maximum particle size 100 μm) 809 (52.5 vol%) (5) melted Silica powder angular (average particle size 15 μm, maximum particle size 100 μm) 346 (22.5 vol%) (6) 3-glycidoxypropyltrimethoxysilane 3 (parts by weight) (7) Polyethylene wax 3 (parts by weight) (8) ) Novolac type brominated epoxy resin (equivalent weight 275) 20 (parts by weight) (9) antimony trioxide 15 (parts by weight) (10) carbon black (average particle size 200 mμm) 2 (parts by weight) Above (1) to (10) Using, was obtained in the same manner as in Example 2 to obtain an epoxy-based encapsulating material. The Tg measured in the same manner as in Example 2 was 125 ° C., and α ₁ between room temperature and Tg was 1.0.
It was × 10 ^-5 ° C ^-1 . On the other hand, as in Example 1, Q
The moisture absorption time (85 ° C., 85% RH) for reflow cracking at FP54 pin was 72 hours, which was good.

Example 4 (1) Silicone-modified bismaleimide resin, Bestlex A-4L (manufactured by Sumitomo Chemical) 100 (parts by weight) (2) 4-methylimidazole 3 (parts by weight) (3) Spherical fused silica powder (average) Particle size 15 μm, maximum particle size 100 μm) 409 (67.5 vol%) (4) 3-glycidoxypropyltrimethoxysilane 3 (parts by weight) (5) Ester wax 3 (parts by weight) (6) Carbon black (average particle size 200 mμm) 1 (parts by weight) The above (1) to (6) are placed on a mixing roll at 80 ° C.,
The mixture was kneaded for 7 minutes, cooled, and then pulverized to obtain a polyimide-based encapsulating material. This 4 × 4 × 20 mm rod-shaped test piece was placed at 180 ° C.
Transfer molding at 70kg / cm ² , 150sec, 200
After post-curing at 2 ° C. for 2 hours, Tg determined in the same manner as in Example 2 was 252 ° C., α ₁ and 0.9 × 10 ⁻⁵ ° C. ⁻¹ . On the other hand, QFP54 p obtained in the same manner as in Example 2
The moisture absorption time (85 ° C., 85% RH) for reflow cracking in the in-package was 168 hours or more, which was extremely good.

Comparative Example 1 (1) o-cresol novolac type epoxy resin (equivalent 195) 80 (parts by weight) (2) phenol novolac (equivalent 107) 50 (parts by weight) (3) 1,8-diazabicyclo (5, 5) 4,0) Undecene-7 3 (parts by weight) (4) Fused silica powder spherical (average particle size 15 μm, maximum particle size 100 μm) 140 (18vol%) (5) Fused silica powder angular (average particle size 15 μm, maximum particle size) 100 μm) 326 (42 vol%) (6) 3-glycidoxypropyltrimethoxysilane 3 (parts by weight) (7) carnauba wax 2 (parts by weight) (8) novolac type brominated epoxy resin (equivalent weight 275) 15 ( (Parts by weight) (9) Antimony trioxide 15 (parts by weight) (10) Carbon black (average particle size 200 mμm) 1.5 (parts by weight) The same as Example 2 using (1) to (10) above. It was obtained an epoxy sealant. Tg determined in the same manner as in Example 2
Was 160 ° C. and α ₁ was 1.9 × 10 ⁻⁵ ° C. ⁻¹ . On the other hand, the moisture absorption time for reflow crack generation in the QFP54 pin package (85 ° C., 85 ° C.) determined in the same manner as in Example 1.
% RH) was as short as 12 hours.

[0016]

EFFECTS OF THE INVENTION In a thin surface mounting type resin-sealed semiconductor device having a Si chip area of 25 mm ² or more or a piece length of 5 mm or more and a package thickness of 3 mm or less, the glass transition point Tg is 140 ° C. If the Tg is 140 ° C or lower, or 220 ° C or higher, the content of fused silica powder as an inorganic filler is 65 to 90 vol%, epoxy type, or Tg
When the temperature is 220 ° C. or higher, it is possible to provide a resin-encapsulated semiconductor device in which crack resistance during reflow after moisture absorption is significantly improved by encapsulating with a sealing material composed of a polyimide system. ..

[0017]

[Brief description of drawings]

1A is a cross-sectional view of a sealing material showing a crack generation state, and FIG. 1B is a diagram showing stress and resin strength generated during solder reflow.

FIG. 2 is a diagram showing a relationship between Tg and high temperature flexural modulus.

FIG. 3 is a diagram showing the relationship between Tg and high temperature bending strength.

FIG. 4 is a diagram showing a relationship between bending elastic modulus and bending strength at high temperature.

FIG. 5 is a diagram showing the relationship between Tg and moisture absorption rate.

FIG. 6 is a diagram showing a relationship between Tg and adhesive force.

FIG. 7 is a diagram showing a relationship between Tg and reflow crack moisture absorption time.

FIG. 8 is a diagram showing the relationship between filler shape, filler content and reflow crack resistance.

FIG. 9 is a diagram showing the relationship between filler shape, filler content and spiral flow.

[Procedure amendment]

[Submission date] April 20, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Resin-sealed semiconductor device

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mount type resin-encapsulated semiconductor device having a large Si chip and a thin package.

[0002]

2. Description of the Related Art Conventionally, a resin-encapsulated semiconductor device that has been developed to be called rice in the industry has a glass transition point Tg of 150 to 180 ° C. after molding and curing, and a natural crystalline silica powder as an inorganic filler. Alternatively, an epoxy resin encapsulant containing 50 to 65 vol% of fused silica powder or a mixture of these fillers is used all over the world. The package form is DIP, SIP, ZIP, TO-92, TO-22
0, TO-3P, TO-126, SOT-23, etc. When Tg is lowered to 150 ° C. or lower, 150 to −55
In a thermal shock test of ℃ (or -65 ℃), there is a problem that elongation at Tg or more causes the Au wire to be broken and the reliability is significantly impaired. To prevent this problem, Tg is set to 15
It has been used while controlling at 0 to 180 ° C.

[0003]

In the resin-encapsulated semiconductor device, the size of the Si chip has become larger and the package has become thinner in recent years. On the other hand, the soldering work for mounting these resin-encapsulated semiconductor devices on a printed wiring board (PCB) is changing from the conventional pin insertion to planar mounting called surface mounting. When a conventional epoxy resin encapsulant is used in a thin package that mounts a large Si chip and this resin-encapsulated semiconductor device is surface-mounted, it absorbs a very slight amount of moisture under natural conditions. However, if this is exposed to a reflow temperature of 200 ° C to 300 ° C where soldering is performed suddenly, a very small amount of water present inside the package is suddenly gasified and becomes an internal pressure, which causes the internal stress to be surrounded. If the breaking strength of the resin layer is exceeded, the resin layer will be easily cracked and the reliability will be significantly impaired. The present invention has been made in view of such circumstances, and an object thereof is to greatly improve the crack resistance during reflow after humidification in a thin resin-sealed semiconductor device mounted with a large Si chip.

[0004]

That is, the present invention is based on Si
In a thin surface-mounting resin-sealed semiconductor device having a chip area of 25 mm ² or more or a side length of 5 mm or more and a package thickness of 3 mm or less, an inorganic filler is used in an amount of 65 to 90.
The present invention relates to a semiconductor device characterized by being molded and encapsulated with a thermosetting resin encapsulant having a glass transition point Tg of vol% of 140 ° C. or lower or 220 ° C. or higher. The area of the Si chip is 25 mm ² or more, or the length of one side is 5 mm or more,
Measures to improve the crack resistance during reflow after humidifying a thin resin-sealed semiconductor device with a package thickness of 3 mm or less are as follows: (1) Breaking strength at high temperature at reflow temperature of 215 to 260 ° C. Augmentation. (2) Reduction of moisture absorption rate (3)
The adhesive strength between the insert such as Si chip and lead frame metal (CuorFe type) and the sealing material can be increased.

Of the above, the high temperature strength enhancement has a Tg of 15
In the conventional epoxy-based encapsulant of 0 to 180 ° C, it means that the strength in the rubber-like region must be increased,
This major enhancement is essentially impossible. Significant enhancement of high temperature strength is possible only by increasing Tg.
However, the relationship between Tg and high-temperature strength has not been clarified so far, and it has not been possible to predict what temperature Tg should be raised to. On the other hand, it is necessary to change the resin system of the raw material in order to greatly increase or decrease Tg. Therefore,
For various epoxy resin and polyimide resin encapsulants,
Tg, high temperature strength, moisture absorption, adhesion and QFP54 pin
Package: 20 x 14 x 2 mmt, Si chip size:
The 6 × 6 mmt lead frame: 42 Alloy was examined in detail for crack resistance during reflow after absorbing moisture. Table 1 shows the skeleton of the basic resin of the resin-based sealing material used.

[0006]

[Table 1]

(1) High temperature strength The relationship between Tg and high temperature bending strength is shown in FIG. The high temperature bending strength strongly depends on Tg, and if Tg is increased, the high temperature strength can be enhanced as expected. It was a remarkable finding that the polyimide system was found to be continuous on the extension line of the epoxy system. This relationship also applies to the relationship between the following Tg, moisture absorption rate, and adhesiveness. It is clear from FIGS. 2, 3 and 4 that the high temperature bending strength is governed by the high temperature bending elastic modulus (hardness). (2) Moisture absorption rate The relationship between Tg and hygroscopicity is shown in FIG. The hygroscopicity also depends on Tg, and when Tg is increased, the hygroscopicity tends to increase,
On the contrary, it is understood that it is necessary to lower Tg in order to lower the hygroscopicity. (3) Adhesiveness The relationship between Tg and adhesiveness is shown in FIG. The adhesiveness also depends on Tg, and when Tg is increased, the adhesiveness tends to decrease.
It was found that the adhesiveness can be greatly enhanced by lowering g. (4) Crack resistance during reflow after moisture absorption of package The QFP54pin is moisture-absorbed at 85 ° C. and 85% RH, taken out appropriately, and subjected to heat treatment at reflow conditions of 215 ° C. and 90 ° C. until the package cracks.
FIG. 7 is a graph in which the moisture absorption time at 85 ° C. and 85% RH was obtained and the relationship between the moisture absorption time and Tg was plotted. Tg of 220 ° C or higher
It was found that when g was 140 ° C. or less, it was differentiated into two poles and the crack resistance during reflow after moisture absorption could be improved (extension of moisture absorption time until crack generation). The former having a high Tg is a polyimide-based encapsulating material, and it is advantageous that high temperature strength is high. The latter, which has a low Tg, is an epoxy-based encapsulant, and is effective in low hygroscopicity and high adhesion. Examples of the polyimide-based resin used in the present invention include bismaleimide-based resins and maleic anhydride-aromatic diamine direct addition reaction-based resins, and epoxy-based resins include bisphenol A type epoxy resins, biphenyl type epoxy resins, There are resorcinol glycidyl ether type epoxy resins and the like. Further, as the curing agent, phenol novolac resin, phenol aralkyl resin, etc. can be used.

Conventionally, since the upper limit temperature of the reliability test of the resin-encapsulated semiconductor device is 150 ° C., it has been standard to set Tg, which is an index of heat resistance, to 150 ° C. or higher to 180 ° C. As described above, when the Tg of the sealing material is 150 ° C. or lower, the elongation in the rubber-like region above Tg cannot be ignored, and the Au wire is broken in the temperature cycle test of 150 to −55 (or −65) ° C. There was a problem that it was easy to do and impaired reliability. However, this thermal shock resistance increases the content of fillers and fused silica that do not diffuse, adsorb, or permeate moisture,
It can be compensated by lowering the coefficient of linear expansion. Increasing the content of fused silica is also effective in reducing the moisture absorption rate and increasing the high temperature strength by increasing the elasticity at high temperatures. Therefore, the content of fused silica in the fused silica powder high-filling epoxy encapsulant vol% and the moisture absorption characteristics (85 ° C., 85% RH),
Table 2 shows the linear expansion coefficient, the high temperature bending strength, and the crack generation state when exposed to the reflow heat treatment condition of 215 ° C. for 90 seconds after absorbing QFP54 pin package and 65 ° C., 95% RH for 72 hours.

[0009]

[Table 2] (Note) *: QFP54pin 20 x 14 x 2 mmt L / F: 42 alloy, chip: 6 x 6 mm 65 ° C 95% RH72h + VPS (215 ° C 90 sec)

As the content of the fused silica powder is increased, the high temperature strength is enhanced together with the improvement of the moisture absorption characteristics such as the reduction of the moisture absorption rate, and the linear expansion coefficient is also reduced, so that the crack resistance during reflow is greatly increased. It was found to improve. Reduction of linear expansion is 150 to -55 (or -6 when Tg is low).
5) It is also extremely effective for preventing Au wire disconnection during temperature cycling at ° C. Next, the shape of fused silica and QFP54pi
Moisture absorption time for crack generation during reflow of n h (85 ℃, 85
% RH), and spiral flow SF (180 ° C, 7
The relationship of 0 kg / cm ² ) is shown in FIGS. Regarding the shape of the fused silica powder, the angular shape is more advantageous than the spherical shape in terms of crack resistance during reflow. However, if the amount of the horny powder is increased, the fluidity is impaired. Therefore, in order to achieve both the fluidity and the crack resistance during reflow, it is preferable to appropriately adjust the horny powder and the spherical powder. In addition to the above resin components and fillers, brominated epoxy resins, flame retardants such as antimony trioxide, and the like can be added as necessary as components that can be added to the encapsulating material in the present invention. The molding conditions for the encapsulant according to the present invention are 165 to 165 in the case of an epoxy resin.
190 ° C, 170 to 20 for polyimide resin
It can be arbitrarily selected from 0 ° C. and 50 to 200 seconds. Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

[0011]

EXAMPLES Example 1 Tg composed of main raw materials having the chemical structure shown in Table 1
2 to 4, 5 and 6 show the relationship between Tg and high temperature bending property, moisture absorption rate, and adhesiveness for various epoxy type encapsulants and polyimide type encapsulants different from each other. Also, using various epoxy type encapsulants and polyimide encapsulants with different Tg, QFP54 pin package (20 x 14 x
2.0 mmt, Si chip size: 6 x 6 mm, lead frame: 42 Alloy) is molded and cured under normal conditions, and this is taken out at 85 ° C and 85% RH for moisture absorption, and immediately reflowed at 215 ° C for heat treatment. The presence or absence of package cracks was observed when exposed for 90 seconds (Florinert: FC-70, saturated vapor layer at boiling point manufactured by Sumitomo 3M). And, until this crack occurs 8
The moisture absorption time at 5 ° C. and 85% RH was determined. FIG. 7 shows the relationship between this reflow cracking moisture absorption time and Tg.

Example 2 (1) Bisphenol A type epoxy (equivalent 500) 80 (parts by weight) (2) Phenol novolac (equivalent 107) 25 (parts by weight) (3) 1,8-diazabicyclo (5,4,0) ) Undecene-7 3 (parts by weight) (4) Fused silica powder spherical (average particle size 15 μm, maximum particle size 100 μm) 257 (32.5 vol%) (5) Fused silica powder angular (average particle size 15 μm, maximum particle size 100 μm) 257 (32.5vol%) (6) 3-glycidoxypropyltrimethoxysilane 3 (parts by weight) (7) carnauba wax 3 (parts by weight) (8) novolac type brominated epoxy resin (equivalent weight 275) 20 (parts by weight) Parts) (9) antimony trioxide 15 (parts by weight) (10) carbon black (average particle size 200 mμm) 2 (parts by weight) The above (1) to (10) are put on a mixing roll to form 90
The mixture was kneaded at 10 ° C. for 10 minutes, cooled, and then pulverized to obtain an epoxy encapsulant. A 4 × 4 × 20 mm rod-shaped test piece of 175 ° C.
Transfer molding at 70kg / cm ² , 90sec, 175
Post-cure at 5 ℃ for 5h and apply TMA at 5 ℃ /
The elongation was calculated while raising the temperature at min, and the temperature at the intersection of the two gradients with different gradients was determined as the glass transition temperature Tg. As a result, the linear expansion coefficient α ₁ between room temperature and Tg was 105 ° C.
It was 4 × 10 ^-5 ° C ^-1 . On the other hand, the moisture absorption time (85 ° C., 85% RH) for reflow cracking in the QFP54 pin package was determined in the same manner as in Example 1, and was found to be 84.
h was good.

Example 3 (1) 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl, biphenyl (equivalent weight 195) 80 (parts by weight) (2) Phenol aralkyl resin represented by the following general formula (equivalent 175) 84 (parts by weight)

[Chemical 1] (3) 1,8-diazabicyclo (5,4,0) undecene-7 3 (parts by weight) (4) fused silica powder spherical (average particle size 15 μm, maximum particle size 100 μm) 809 (52.5 vol%) (5) melted Silica powder angular (average particle size 15 μm, maximum particle size 100 μm) 346 (22.5 vol%) (6) 3-glycidoxypropyltrimethoxysilane 3 (parts by weight) (7) Polyethylene wax 3 (parts by weight) (8) ) Novolac type brominated epoxy resin (equivalent weight 275) 20 (parts by weight) (9) antimony trioxide 15 (parts by weight) (10) carbon black (average particle size 200 mμm) 2 (parts by weight) Above (1) to (10) Using, was obtained in the same manner as in Example 2 to obtain an epoxy-based encapsulating material. The Tg measured in the same manner as in Example 2 was 125 ° C., and α ₁ between room temperature and Tg was 1.0.
It was × 10 ^-5 ° C ^-1 . On the other hand, as in Example 1, Q
The moisture absorption time (85 ° C., 85% RH) for reflow cracking at FP54 pin was 72 hours, which was good.

Example 4 (1) Silicone-modified bismaleimide resin, Bestlex A-4L (manufactured by Sumitomo Chemical) 100 (parts by weight) (2) 4-methylimidazole 3 (parts by weight) (3) Spherical fused silica powder (average) Particle size 15 μm, maximum particle size 100 μm) 409 (67.5 vol%) (4) 3-glycidoxypropyltrimethoxysilane 3 (parts by weight) (5) Ester wax 3 (parts by weight) (6) Carbon black (average particle size 200 mμm) 1 (parts by weight) The above (1) to (6) are placed on a mixing roll at 80 ° C.,
The mixture was kneaded for 7 minutes, cooled, and then pulverized to obtain a polyimide-based encapsulating material. This 4 × 4 × 20 mm rod-shaped test piece was placed at 180 ° C.
Transfer molding at 70kg / cm ² , 150sec, 200
After post-curing at 2 ° C. for 2 hours, Tg determined in the same manner as in Example 2 was 252 ° C., α ₁ and 0.9 × 10 ⁻⁵ ° C. ⁻¹ . On the other hand, QFP54 p obtained in the same manner as in Example 2
The moisture absorption time (85 ° C., 85% RH) for reflow cracking in the in-package was 168 hours or more, which was extremely good.

Comparative Example 1 (1) o-cresol novolac type epoxy resin (equivalent 195) 80 (parts by weight) (2) phenol novolac (equivalent 107) 50 (parts by weight) (3) 1,8-diazabicyclo (5, 5) 4,0) Undecene-7 3 (parts by weight) (4) Fused silica powder spherical (average particle size 15 μm, maximum particle size 100 μm) 140 (18vol%) (5) Fused silica powder angular (average particle size 15 μm, maximum particle size) 100 μm) 326 (42 vol%) (6) 3-glycidoxypropyltrimethoxysilane 3 (parts by weight) (7) carnauba wax 2 (parts by weight) (8) novolac type brominated epoxy resin (equivalent weight 275) 15 ( (Parts by weight) (9) Antimony trioxide 15 (parts by weight) (10) Carbon black (average particle size 200 mμm) 1.5 (parts by weight) The same as Example 2 using (1) to (10) above. It was obtained an epoxy sealant. Tg determined in the same manner as in Example 2
Was 160 ° C. and α ₁ was 1.9 × 10 ⁻⁵ ° C. ⁻¹ . On the other hand, the moisture absorption time for reflow crack generation in the QFP54 pin package (85 ° C., 85 ° C.) determined in the same manner as in Example 1.
% RH) was as short as 12 hours.

[0016]

EFFECTS OF THE INVENTION In a thin surface mounting type resin-sealed semiconductor device having a Si chip area of 25 mm ² or more or a piece length of 5 mm or more and a package thickness of 3 mm or less, the glass transition point Tg is 140 ° C. If the Tg is 140 ° C or lower, or 220 ° C or higher, the content of fused silica powder as an inorganic filler is 65 to 90 vol%, epoxy type, or Tg
When the temperature is 220 ° C. or higher, it is possible to provide a resin-encapsulated semiconductor device in which crack resistance during reflow after moisture absorption is significantly improved by encapsulating with a sealing material composed of a polyimide system. ..

[0017]

[Brief description of drawings]

1A is a cross-sectional view of a sealing material showing a crack generation state, and FIG. 1B is a diagram showing stress and resin strength generated during solder reflow.

FIG. 2 is a diagram showing a relationship between Tg and high temperature flexural modulus.

FIG. 3 is a diagram showing the relationship between Tg and high temperature bending strength.

FIG. 4 is a diagram showing a relationship between bending elastic modulus and bending strength at high temperature.

FIG. 5 is a diagram showing the relationship between Tg and moisture absorption rate.

FIG. 6 is a diagram showing a relationship between Tg and adhesive force.

FIG. 7 is a diagram showing a relationship between Tg and reflow crack moisture absorption time.

FIG. 8 is a diagram showing the relationship between filler shape, filler content and reflow crack resistance.

FIG. 9 is a diagram showing the relationship between filler shape, filler content and spiral flow.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 23/29 23/31

Claims (4)

[Claims] 1. A thin surface-mounting resin-encapsulated semiconductor device having a Si chip area of 25 mm ² or more, or a side length of 5 mm or more, and a package thickness of 3 mm or less, wherein an inorganic filler is used in an amount of 65-65. A semiconductor device, which is encapsulated with a thermosetting resin encapsulant having a glass transition point Tg of 90 vol% of 140 ° C. or lower or 220 ° C. or higher. 2. The semiconductor device according to claim 1, wherein the thermosetting resin encapsulant having a Tg of 140 ° C. or lower is an epoxy type. 3. The semiconductor device according to claim 1, wherein the thermosetting resin encapsulant having a Tg of 220 ° C. or higher is a polyimide type. 4. The inorganic filler is fused silica.
The semiconductor device described.