JP4030930B2 - Semiconductor power module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor power module which is improved in reliability and heat dissipation property using a substrate of metal, such as inexpensive Al, Cu, or the like, without using an insulating substrate of a material, such as AlN, Al<SB>2</SB>O<SB>3</SB>or the like, so as to cope with an increase in size and output power. <P>SOLUTION: The linear expansion coefficient of filler epoxy resin 15 is set higher than that of solder 3 or at (24&plusmn;3)&times;10<SP>-6</SP>/&deg;C, its Young's modulus is set at 1 to 12 Gpa, preferably at 5 to 8 Gpa. A semiconductor chip 1 is surrounded with the epoxy resin 15 that has physical properties near to those of the solder 3, is somewhat soft, and high in adhesion, so that the semiconductor chip 1 can be protected against large stress acting on it so as to protect its element unit against interface delamination damage, and the solder 3 can be ensured a longer service life. The glass transition temperature Tg of the filler resin 15 is set at a temperature of 150&deg;C or above, so that an adverse affect caused by the thermal expansion of the filler resin 15 at a high temperature such as a secondary reflow or the like can be restrained. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a semiconductor power module widely used for home appliances or industrial use.
[0002]
  A semiconductor power module with a built-in semiconductor switching element has high thermal conductivity in consideration of the amount of heat generated by the switching element.Heat dissipation boardIn general, an insulating plate made of a material having high thermal conductivity and high electrical insulation is used.
[0003]
In a medium to large capacity product having a large calorific value, a ceramic having a high thermal conductivity is mainly used as an insulating plate although it is expensive. In relatively small-capacity products, an inexpensive insulating resin having a low thermal conductivity is used.
[0004]
Patent Document 1 discloses two examples of semiconductor power modules. In FIG. 2, a semiconductor chip is soldered to the upper surface of the heat dissipation board via an insulating plate or the like, filled with silicone gel, and sealed from above with a hard epoxy resin. The reason why soft silicone gel is used is to prevent stress such as thermal deformation of the case from being applied to the semiconductor chip and the fine metal wires.
[0005]
Further, in FIG. 1 of Patent Document 1, the linear expansion coefficient is 5 × 10.^-6/ ° C. to 25 × 10^-6A structure in which a semiconductor chip is directly sealed with a resin at / ° C. has been proposed.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-5742 (FIGS. 1 and 2, overall)
[0007]
[Problems to be solved by the invention]
Patent Document 1 does not touch on heat dissipation in a semiconductor chip or physical properties other than the linear expansion coefficient of the resin to be filled.^-6If the temperature is higher than / ° C., the generated stress increases and the aluminum wiring is likely to break. "It has said.
[0008]
Chips are becoming larger and higher in output, and cost reduction is required. It is important to realize high heat dissipation and improved reliability at a low cost due to high output. It has become.
[0009]
  The object of the present invention is to use inexpensive AlN, Cu, etc. without using an expensive AlN insulating substrate or Al2O3 insulating substrate.Heat dissipation boardIs used to provide a semiconductor power module with improved reliability and heat dissipation.
[0010]
[Means for Solving the Problems]
In one aspect of the present invention, in a semiconductor power module in which a semiconductor chip having a metallized surface soldered to a heat diffusion plate is put in a case and the resin is filled in the case, the linear expansion coefficient of the resin is greater than the linear expansion coefficient of the solder. The thermal diffusion plate includes a sintered formed body obtained by mixing and sintering Cu and a powder of a low expansion material, and a Cu plate connected to the sintered formed body.
[0011]
Specifically, the linear expansion coefficient of this resin is (20 to 45) × 10.^-6/ ° C.
[0012]
By selecting the linear expansion coefficient of the resin, the stress concentration at the solder crack starting point is suppressed, and the chip is protected and restrained with a level of stress that does not cause destruction of the semiconductor chip. By adopting this heat diffusion plate, the difference in the coefficient of linear expansion from the semiconductor chip is further reduced, so that stress and strain can be suppressed and the effect of the resin can be exhibited more remarkably.
[0013]
In another aspect of the present invention, in addition to the selection of the resin, the Young's modulus of the resin at room temperature (15 to 20 ° C.) is set to 1 to 12 GPa.
[0014]
That is, the periphery of the semiconductor chip is softened to the same level as that of the solder and is surrounded by an epoxy resin having an adhesive force. Thus, the semiconductor chip is mechanically protected so as not to be subjected to a large stress, the semiconductor chip is protected, the interface peeling failure is prevented, and the life of the solder is guaranteed.
[0015]
In another aspect of the present invention, a resin having a glass transition temperature (Tg) of 150 ° C. or higher is used in addition to the selection of the resin.
[0016]
Thereby, the reliability of the semiconductor power module can be improved by avoiding a rapid (2 to 3 times) increase in the linear expansion coefficient due to reaching the glass transition temperature.
[0017]
In a desirable embodiment of the present invention, the Young's modulus of the resin to be filled is 3 to 10 GPa, more desirably 5 to 8 GPa.
[0018]
As a result, the semiconductor chip can be restrained, the semiconductor chip interface peeling can be prevented, and the life of the solder can be expected to be improved.
[0019]
In another embodiment of the present invention, the portion in contact with the surface of the semiconductor chip is thinly coated (0.01 to 1 mm) with a softer resin (small Young's modulus) than the resin, and the resin is coated on the periphery of the chip. Fill to cover.
[0020]
As a result, in particular, as a countermeasure when the surface of the semiconductor chip is weak, mounting with more emphasis on element protection is possible.
[0021]
Furthermore, in a preferred embodiment of the present invention, in addition to the above structure, a heat sink is arranged around the semiconductor chip to dissipate heat from above.
[0022]
Other objects and features of the present invention will become apparent from the following description of embodiments.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view of a semiconductor power module according to a first embodiment of the present invention. A power semiconductor chip 1 such as a MOSFET is soldered to a Ni-plated Cu heat diffusion plate 2 with Pb-5Sn solder 3 in a hydrogen furnace. On the other hand, a resin insulating layer 5 is formed on the upper end portion of the Al heat dissipation substrate 4, and an Ni-plated Cu foil conductor electric circuit 61 is formed on the resin insulating layer 5. A lead-free Sn-3Ag-0.5Cu solder paste is applied to the electric circuit 61, and the back surface of the heat diffusion plate 2 to which the semiconductor chip 1 is soldered is positioned and mounted, and then a reflow furnace of max 240 ° C. Solder with solder 7. The thickness of the electric circuit 61 made of a Cu foil conductor is about 70 μm, and the thickness of the thermal diffusion plate 2 is about 1 to 2 mm in consideration of the effect of thermal diffusion. The thermal diffusion plate 2 was provided with a sintered formed body obtained by mixing and sintering Cu and a powder of a low expansion material, and a Cu plate integrated with the sintered formed body during fixation, pressure bonding, or sintering. It is a complex. Specifically, the low expansion material is as follows. (1) A structure in which Cu alloy, Cu and Cu2O, Cu and Mo, Cu and C (carbon fiber) or Cu and Invar powder are mixed at a fixed ratio and molded. Or (2) Cu- (Cu / Cu2O) -Cu, Cu- (Cu / Mo) -Cu, Cu- (Cu / C) -Cu, or Cu- (Cu) having a sandwich structure with the above molded body as a core. / Invar) -Cu anisotropic structure.
[0024]
The electric circuit 61 is connected by a thin metal wire 8 made of Al, and further wired to the external connection terminal 9. The IC 10 is bonded to the electric circuit 62 on the control board 11 with solder 12. The control board 11 is a glass epoxy multilayer board, and is fixed to the resin insulating layer 5 with an adhesive, and the semiconductor chip 1 and the control board 11 are electrically connected by a thin metal wire 8. The external connection terminal 13 is soldered to the connection terminal of the control board 11 with the solder 12. These are housed in a case 14 and sealed with an epoxy-based filling resin 15 having a linear expansion coefficient equal to or greater than that of the solder 3.
[0025]
In this embodiment, the linear expansion coefficient is 24 × 10^-6In the case of the epoxy filled resin 15 having a Young's modulus of 8 GPa at / ° C. and room temperature, it was found that almost no crack growth was observed in the power cycle test and the temperature cycle test. Compared to the structure filled with silicone gel, it was found that a life improvement of about 3 to 10 times can be expected. The mechanism for improving the service life is to suppress stress concentration at the solder crack starting point by selecting an appropriate resin, and to protect and restrain the chip with a level of stress that does not cause the semiconductor chip 1 to break down. Furthermore, the heat diffusion plate 2 is not made of Cu, and a sintered formed body obtained by mixing and sintering Cu and a powder of a low expansion material, and a Cu plate in which the sintered formed body is fixed, pressed, or integrated. By using the composite including the above, the difference in coefficient of linear expansion from the semiconductor chip is further reduced. For this reason, the values of stress and strain were reduced, and it was confirmed that the effect of the resin 15 was further exhibited. Specifically, as a low expansion material, Cu-Mo, Cu-Cu₂O, Cu-Invar (linear expansion coefficient: about 10 × 10^-6/ ° C.) was used for sintering.
[0026]
The linear expansion coefficient of the resin 15 does not need to be adjusted to the solder 3 with high accuracy, and is equivalent to the solder 3 (24 ± 3) × 10.^-6/ ° C. includes values of Sn—Pb-based and Sn—Ag—Cu-based solder composition ranges, and can be handled with a common resin.
[0027]
On the other hand, it was found that, even when the same resin system contains a large amount of filler and the Young's modulus is increased to 20 GPa or more, the probability of causing Si peeling at the interface between the resin 15 and the semiconductor chip 1 and the destruction of the element portion increases. When the Young's modulus is 15 to 20 GPa, it is at the boundary level between when it occurs and when it does not occur depending on the severity of the structure and test conditions.
[0028]
Therefore, by covering the whole with the epoxy-based filling resin 15 having the specified physical properties, the semiconductor chip 1 can be prevented from being broken and the cracks of the solder 3 can be prevented from progressing without using an expensive heat dissipation substrate. We have made it possible to provide semiconductor power modules.
[0029]
The role of the filling resin that brings about high reliability with low-cost mounting according to the present invention will be described in detail below.
[0030]
In the present invention, by filling the resin 15 having mechanically specified physical properties, the life of the solder 3 joint portion between the semiconductor chip 1 and the Cu heat diffusion plate 2 is greatly improved. In order to improve the lifetime, the linear expansion coefficient of the resin is (20 to 45) × 10 which is 3 or more of solder.^-6/ ° C. Further, by lowering the Young's modulus and surrounding the periphery of the semiconductor chip 1 with a resin 15 having physical properties that do not place a stress on the semiconductor chip 1, it is free from influence on the element, interface peeling of the semiconductor chip, and the like. Then, the resin 15 surrounds and restrains the solder 3 and the semiconductor chip 1, that is, the resin 15 plays a role of relaxing the stress concentration of the solder 3 at the end of the semiconductor chip 1. To prevent. In this case, the stress-strain characteristic of the resin 15 can be approximated by thermoelasticity, but in the case of the solder 3, it is approximated by thermoelasticity.
[0031]
FIG. 2 is a graph showing models of temperature dependence of the stress-strain curve (A) of the filling resin 15 and the stress-strain curve (B) of the solder 3. Even if a large strain occurs between the semiconductor chip 1 and the solder 3, as can be seen from FIG. 2B, since the solder 3 is plastically deformed, no large stress is applied at a high temperature. Further, even if a large stress is applied at a low temperature, it is difficult to generate a stress enough to cause a crack in the semiconductor chip. On the other hand, in the case of the resin 15 shown in FIG. 2A, the Young's modulus decreases and the stress decreases at high temperatures due to thermoelasticity, but the Young's modulus is high and the stress is high at low temperatures. Accordingly, when a temperature difference occurs, a large stress proportional to the strain amount acts, and if there is no resin adhesion, there is a risk of peeling at the interface between the chip 1 and the resin 15 due to shear stress. In a severe power cycle test using a resin with a relatively high Young's modulus (15 Gpa at room temperature of 15 to 20 ° C.), the fracture at the interface between the semiconductor chip 1 and the resin is confirmed, and a large stress acts in the analysis. Was confirmed.
[0032]
Thus, as a result of confirmation by various experiments and analyses, basically, the linear expansion coefficient of the resin is higher than that of the solder 3 (20 to 45) × 10.^-6The Young's modulus at room temperature (15 to 20 ° C.) should be 1 to 12 Gpa (preferably 3 to 10 Gpa). By using such a resin 15, it was possible to prevent the interface breakage of the semiconductor chip 1 within the range of severe acceleration test conditions. In addition, as can be seen from the analysis result of FIG. 6 described later, since the distortion of the solder 3 is reduced as compared with the silicone gel filling structure, it has been found that the life of the solder 3 is also improved.
[0033]
FIG. 3 is a graph showing an end cross-sectional view for illustrating a mechanism of occurrence of cracking of a semiconductor chip in a resin-filled structure, and a stress-strain curve model of the filled resin and solder. In the resin-coated structure, an indication of whether or not the semiconductor chip 1 is broken by the resin 15 will be described. A place where the semiconductor chip 1 is easily broken is the chip end portion 101. In particular, in a high breakdown voltage semiconductor element such as an IGBT, chipping at the end causes a decrease in breakdown voltage. FIG. 3A is a cross-sectional model in which the semiconductor chip 1 is soldered to the heat diffusion plate 2 with the solder 3 and covered with the resin 15, and the chip end portion 101 where the stress is maximum on the surface of the semiconductor chip 1, A position 301 where the maximum equivalent strain that becomes the starting point of the crack of the solder 3 is taken is shown. FIG. 3B shows a simple view of whether or not the semiconductor chip 1 is cracked. The stress σ at the level of occurrence of breakage of the chip 1 within the range of the strain Δε caused by the temperature difference._BThis indicates that whether or not cracking occurs is determined by whether or not. When a resin 151 having a large Young's modulus E at room temperature is used, when a strain Δε due to a temperature difference occurs, a stress σ1 proportional to that acts on the semiconductor chip 1, exceeding the limit of the fracture stress of the chip at point a. Causes a crack at 1 boundary. On the other hand, when the resin 152 having a small Young's modulus E is used, the fracture stress of the chip 1 is not exceeded by the point b, and interface fracture does not occur.
[0034]
Furthermore, there is a glass transition temperature Tg as a problem peculiar to the resin, which greatly affects the reliability. In general, a resin having a low Tg is excellent in workability because it is excellent in workability. However, since the linear expansion coefficient rapidly rises about three times above the Tg temperature, it is often betrayed by the reliability test result. Therefore, it is a highly reliable condition that the maximum temperature for use environment conditions, acceleration test, secondary reflow, etc. is also Tg temperature or less. At least for the power cycle test, the minimum Tg is required to be 150 ° C. or higher, and it is desirable that the Tg is about 170 ° C. As a result, severe environmental conditions, secondary reflow and other high-temperature heat damage can be minimized, and high reliability can be ensured.
[0035]
The linear expansion coefficient and the glass transition temperature Tg were measured using a thermophysical tester TMA-1500 manufactured by Vacuum Riko. A cured specimen having a thickness of 4 mm was heated in a compression mode at a rate of 1 ° C. per minute, and the temperature characteristics of elongation were measured. The linear expansion coefficient α was obtained from the temperature characteristic of elongation, and the glass transition temperature was the inflection point of the temperature line of elongation. Since Tg takes an inflection point, it is difficult to determine exactly 150 ° C. because there is some deviation.
[0036]
  4A to 4DThese are the graphs which show the relationship between the filler with respect to filling resin, the addition of a flexibilizer, and filling resin physical property. Effect of filler blending amount and flexibilizer addition amount that determines mechanical properties of epoxy-based filling resin 15 excellent in adhesion to Si etc. on linear expansion coefficient and Young's modulus, and by flexibilizer addition amount The influence on the relationship between the coefficient of linear expansion and Young's modulus will be described. AER-8501 (manufactured by Adeka) and CEL-2021P (manufactured by Daicel) were used as the epoxy compounds, the curing agent was acid anhydride, MHAC-P (manufactured by Hitachi Chemical Co., Ltd.), and the flexibility was X-22-166C. (Shin-Etsu Chemical Co., Ltd.) was used. In addition, dispersant S-2 (manufactured by Hitachi Chemical Co., Ltd.), surfactant A-187 (manufactured by Nihon Unika Co., Ltd.), and filler FB-30X (manufactured by Electrochemical Co., Ltd.) were used. It is a one-part solvent-free system and has a viscosity of 520 poise at 25 ° C. and was used for potting. For impurity concentration measurement, the cured product is pulverized to 100 mesh or less, and 5 gf of this fine powder and 50 ml of deionized water are placed in a Teflon (registered trademark) to SUS double container and held at 120 ° C. for 240 hours, and the extracted ion component is ion chromatographed. This was done using a graph. Na +, K +; 1 ppm, Cl-; 5 ppm. The curing conditions are 110 ° C. (10 h) / 200 ° C. (10 h), and Tg is 170 ° C. In addition, it is not necessary to use a one-component resin for potting and molding a power module, and an easy-to-use two-component resin may be used. Moreover, as long as the structure allows the solvent to easily escape, a solvent system with less restrictions on the resin composition and the like may be used instead of a solvent-free system, so that there is an advantage that a wide range of resin systems can be selected. Various examinations were performed by changing the blending amount with the above composition.
[0037]
  4A.These show the relationship between a linear expansion coefficient and a Young's modulus at the time of changing the compounding quantity (Vol%) of a quartz filler to the said epoxy resin. It is volume% (Vol%) which added the epoxy compound and the filler. The relationship between the epoxy linear expansion coefficient and the Young's modulus is inversely related, and as shown in the figure, the filler content needs to be in the range of 20 to 55 vol%. In order to set the linear expansion coefficient to 27 × 10 −6 / ° C. which is the value of solder (in the case of Pb-5Sn), the filler content needs to be about 50 vol%. When the material is soft with an epoxy system, even if a filler is blended, the resin has a low Young's modulus for the blending ratio. Therefore, the Young's modulus is about 8 GPa at room temperature with this epoxy material.
[0038]
  4B.These show the physical properties when a rubber flexing agent is added to a resin containing no filler in the same epoxy resin system. Epoxy silicones, amino silicones, hydroxy silicones and the like can be used as the silicone system that does not deteriorate at a high temperature as the flexibilizing agent. Here, epoxy silicone excellent in terms of solubility; X-22-166C manufactured by Shin-Etsu Chemical Co., Ltd. was used. When the base resin is determined, the linear expansion coefficient and Young's modulus are determined by the amount of filler, and the influence of the amount of the flexibilizer added is small. The flexibilizer is premised to be dispersed as fine particles, and when it is 15 mass% or more, it cannot be uniformly dispersed. On the contrary, the level of 10 ± 5% is desirable from the demerit of increasing the linear expansion coefficient.
[0039]
  4C.These are the figures explaining the evaluation result which investigates the disconnection by the terminal part destruction of a board | substrate with respect to the compounding rate of a filler and rubber | gum. A Si chip was connected by a flip chip on a soda glass substrate (linear expansion coefficient: 9.3 × 10 −6 / ° C.), which was thinly wired and easily broken. A resin was filled in the gap and the periphery, and after curing, a temperature cycle test (−40 to 100 ° C.) was performed, and an evaluation method for examining disconnection due to breakage of the element due to resin physical properties and the terminal portion of the substrate was adopted. Although it is not a power module structure, it is an evaluation method suitable for examining the thermal stress effect of a resin on a substrate and a chip. The rubber was expressed in parts by weight with respect to 100 gf of epoxy resin. If the compounding ratio for dispersing rubber is 20 parts by weight (corresponding to 16,7%) or more, the dispersion becomes non-uniform, the linear expansion coefficient itself is large, the linear expansion coefficient after mixing becomes large, and heat fatigue resistance It will cause the decrease. As a determination method, the case where the lifetime of the structure without resin was shorter was marked with “X”, and the case where it was long was marked as “Excellent”: Δ and markedly marked as “Good” depending on the degree. From the results, it can be seen that the rubber compounding amount is preferably 10 ± 5 mass% (5 to 15 mass%) in consideration of uniform dispersibility. The effect of rubber does not seem to be so great with changes in Young's modulus, but it seems to have an impact mitigating action against sudden temperature changes during thermal shock.
[0040]
  4DThese are graphs showing the relationship between the Young's modulus and the linear expansion coefficient in the filled resin 15. In the range of the coefficient of linear expansion of the solder, the composition in which the desired Young's modulus (5 to 10 GPa) is in the range 40 (shaded part) and 11% of the flexibilizer indicated by the broken line is added is in an appropriate region. . In this resin system, if the Young's modulus is reduced to about 3 GPa, chip breakage can be prevented, but the linear expansion coefficient increases, so there is a trade-off relationship in which the contribution to the improvement of the solder life is reduced.
[0041]
FIG. 5 is a graph of linear expansion coefficient versus chip stress and solder strain showing the physical properties and reliability of filled resin for obtaining design guidelines for a resin structure power module. With the cross-sectional model structure shown in the graph of FIG. 5A, a three-dimensional elastoplastic analysis was performed by the finite element method of the equivalent stress of the semiconductor chip end portion 101 and the equivalent strain of the solder crack starting point 301 in the power cycle test. The temperature profile is a proven change of 120 ° C. → 20 ° C. → 120 ° C. → 20 ° C., the equivalent stress amplitude of the semiconductor chip end portion 101 generated by the temperature change of 1.5 cycles and the equivalent at the solder crack starting point 301. The strain amplitude was determined. In addition to the equivalent stress, the principal stress, σx, σy, σz, etc. were also evaluated as stress acting on the surface of the semiconductor chip. However, since this is almost proportional to the equivalent stress, it is evaluated here with the equivalent stress. did.
[0042]
From FIG. 5A, in the case of the same Young's modulus, the linear expansion coefficient of the resin is (20 to 45) × 10 at a low Young's modulus of 15 GPa or less.^-6The linear expansion coefficient of resin is equivalent to that of solder in a wide range of / ° C (28 x 10^-6It can be seen that it is minimized at the / ° C level. However, when the Young's modulus exceeds 15 GPa, the equivalent stress applied to the chip surface tends to increase rapidly. That is, when the Young's modulus of the resin exceeds 15 GPa, the linear expansion coefficient of the resin is 45 × 10^-6At / ° C. or higher, the equivalent stress applied to the chip surface increases. Therefore, as an optimal resin design, first, the linear expansion coefficient of the resin 15 is (20 to 45) × 10.^-6/ C. Secondly, it is important to keep the Young's modulus of the resin 15 at room temperature low to 15 GPa or less and to reduce the equivalent stress applied to the chip surface. Use of a resin having a low Young's modulus is considered to have a great effect in preventing the destruction of the semiconductor chip element portion, the Al conductor portion, the Si interface, and the like. From FIG. 5 (B), the linear expansion coefficient of the resin 15 is (20 to 45) × 10.^-6In the case of the same Young's modulus in the range of / ° C., it can be seen that the higher the Young's modulus of the resin 15 is, the smaller the equivalent strain at the solder crack starting point is, and the smaller the linear expansion coefficient of the resin 15 is. In addition, the linear expansion coefficient of the resin is (10 to 45) × 10 compared to the broken silicone gel sealing structure.^-6In a wide range of / ° C., the equivalent strain of the solder shows a low value, and the life of the solder is considered to be longer than that of the silicone gel sealing structure. Even in an actual acceleration test, it has been confirmed that in this resin structure, the life reduction due to solder does not occur until the life reduction due to another cause occurs. This is considered to be an effect of relaxing the stress concentration of the solder 3 by the resin 15 and could be confirmed by a finite element method analysis.
[0043]
  FIG. 6 is a graph of linear expansion coefficient versus chip stress and solder strain showing the physical properties and reliability of the filled resin.4A.The linear expansion coefficient of the resin is plotted on the horizontal axis, and the equivalent stress acting on the semiconductor chip surface element portion is plotted on the vertical axis. The broken line is the equivalent strain of the solder crack starting point when the whole is covered with silicone gel. In the range 601 (shaded area) where the linear expansion coefficient of the resin 15 is (20 to 45) × 10 −6 / ° C., the resin-coated structure of the present embodiment is more of the solder 3 than the structure coated entirely with silicone gel. The equivalent strain at the crack starting point 301 is small. Therefore, when the resin 15 having the physical properties of this embodiment is used, the solder distortion is smaller than that of the silicone gel sealing structure, so that the disconnection due to the solder is reduced. Further, the equivalent stress σ of the semiconductor chip end portion 101 is also small and is in the region 602 (shaded portion), and the element portion is not easily broken, peeling at the interface, and the like.
[0044]
FIG. 7 is a graph of analysis results showing the relationship between the Young's modulus of the filled resin and the restraint by the resin. When the Young's modulus of the resin was changed, the resin 42 was put between the semiconductor chip 1 (10 × 0.5 mm thickness) and the alumina substrate 41 (10 × 1 mm thickness), and the temperature was changed from 150 ° C. to −55 ° C. At this time, the relative displacement (ΔL) of both of the outermost peripheral portions was obtained by two-dimensional thermoelastic-plastic analysis and indicated on the vertical axis. The linear expansion coefficient of the resin 42 is 25 × 10^-6Calculated as / ° C. 7 that the Young's modulus of the resin 42 that restrains the displacement is at least 1 GPa or more. Furthermore, the Young's modulus of the resin 42 that surely shows the effect of restraining the chip is 3 GPa or more. When the pressure is 12 GPa or more, the stress acting on the interface of the Si chip 1 is increased, and the influence on the chip element part, chip interface peeling, element part destruction, chip cracking, and the like are likely to occur. For this reason, a resin having a high Young's modulus is also a problem from the viewpoint of protecting the weak semiconductor chip surface. In addition, it may have weak strength due to product variations, and it is still important to lower the Young's modulus to ensure high yield and high reliability. Differences due to physical properties were also confirmed by three-dimensional elasto-plastic analysis using the finite element method. In particular, when there is a problem in the element portion, it is possible to coat only the chip surface thinly with silicone gel or the like and fill the periphery of the chip with this resin.
[0045]
In measuring the Young's modulus (flexural modulus), the cured product was cut to 5 × 10 × 100 mm to prepare a bending test piece defined in JIS-6911. This was measured by Shimadzu Autograph DSS-5000 by a both-end directed centralized load method with a bending speed of 1 mm / min and a fulcrum distance of 80 mm.
[0046]
It is as follows when the above examination is summarized and the physical properties of the filling resin for obtaining high reliability of the semiconductor power module are arranged.
[0047]
(1) Linear expansion coefficient: More than solder (20-45) × 10^-6/ ° C.
[0048]
(2) Young's modulus: 1 to 12 GPa (preferably 3 to 10 GPa).
[0049]
(3) Glass transition temperature Tg: 150 ° C. or higher. Desirably 170 ° C or higher.
[0050]
(4) Excellent adhesion to semiconductor chips and substrates.
[0051]
(5) Thermal shock is reduced by dispersing high-temperature stable fine particle rubber such as silicone gel.
[0052]
(6) Impurity concentration: Na⁺, K⁺≦ 1ppm, Cl^-≦ 5ppm
By managing these (1) to (6), it is possible to realize highly reliable mounting in the semiconductor power module.
[0053]
FIG. 8 is a sectional view of a semiconductor power module according to the second embodiment of the present invention. The same reference numerals as those in FIG. 1 represent the same items, and repeated explanations are avoided as much as possible. The resin insulating layer 5 is provided on the upper surface of the Cu heat dissipation substrate 4. On top of this, an electrode (thermal diffusion plate) 2 made of Ni plating Cu prepared by punching or the like is pasted with an adhesive. The resin insulating layer 5 has a thickness that varies depending on the withstand voltage. Here, 160 μm is selected as the thickness that can guarantee the withstand voltage. Then, a lead-free solder paste (RMA type flux) 3 of Sn-3Ag-0.5Cu (melting point: 217 to 221 ° C.) was printed to a thickness of about 250 μm. On top of this, after mounting the 4.9 mm semiconductor chip 1, the semiconductor chip 1, IC 10, components, etc. are soldered by reflow in nitrogen at a temperature of max 240 ° C. After cleaning with flux, an aluminum wire 8 is ultrasonically wire-bonded to the terminal portion of the element, and the other terminal is ultrasonically wire-bonded on a Ni-plated Cu terminal 61 bonded to the insulating layer 5 with an adhesive. It is. On the other hand, the control board 11 on which electronic parts such as a microcomputer are mounted is mainly composed of a multilayer glass epoxy board. It is ideal that the multilayer glass epoxy substrate is first bonded to the Cu heat dissipation substrate 4 and then reflowed simultaneously with the connection of the semiconductor chip 1. However, due to process restrictions such as printing, the components mounted on the multilayer glass epoxy substrate are reflowed in a separate process in advance, and after the semiconductor chip 1 is soldered to the Cu heat dissipation substrate 4, the components mounted multilayer glass epoxy control The substrate 11 may be bonded to the Cu heat dissipation substrate 4. The control substrate 11 made of multilayer glass epoxy on which the IC 10 and components are mounted is separated from the power element 1 part, and an adhesive having poor thermal conductivity and a glass epoxy substrate are interposed. Therefore, the temperature does not rise so high that the microcomputer malfunctions. This structure is a system in which an epoxy-based filling resin 15 is potted on a plastic case 14, but a mold system that is advantageous for cost reduction can be used for mass production. The mechanical property values of the resin 15 after curing are as described above.
[0054]
In this embodiment, the electrode 61 manufactured by punching is attached to the insulating layer 5, and the external connection terminal 13 on the control side has a flat lead type structure.
[0055]
Also in this embodiment, the linear expansion coefficient is 24 × 10.^-6In the case of the epoxy filled resin 15 having a Young's modulus of 8 GPa at / ° C. and room temperature, almost no crack growth is observed in the power cycle test and the temperature cycle test.
[0056]
FIG. 9 is a sectional view of a semiconductor power module according to the third embodiment of the present invention. The same reference numerals as those in FIG. 1 and FIG. About 0.1 t of Ni-plated Cu foil 62 is pasted on the insulating layer 5 and a pattern is formed by etching. The control-side external connection terminal 13 has a pin-type structure. In this structure, the semiconductor chip 1 connected in advance to the thermal diffusion plate 2 with Pb-5Sn high-temperature solder 3 is further connected with low-temperature Sn-3Ag-0.5Cu solder 16. As a combination of the high-temperature solder 3 and the low-temperature solder 16, the semiconductor chip 1 side is a high-temperature solder 3, and a Pb-rich Pb—Sn solder such as Pb-5Sn is a general composition. The combination of the low-temperature solders 16 can be a wide variety of eutectic systems such as Sn—Pb, Sn—Ag—Cu, and Sn—Cu. When limited to lead-free, the high temperature system is Sn-5Sb (melting point: 232 to 240 ° C.) as an example of the Sn—Sb system. As a solder 16 capable of ensuring reliability in a high temperature region in a low temperature system that enables this composition and temperature hierarchy, there is a solder in which 5 to 10% of In is added to a Sn—Ag—Cu, Sn—Cu eutectic system. This is excellent in mechanical properties, relatively flexible, and can be connected at a maximum of 230 ° C. by using a furnace having an excellent furnace temperature distribution. If a lead-free composition can be used for retrofitting, a Sn system can be used for high temperatures. The lead-free composition includes Sn-9Zn (melting point: 199 ° C.) or Sn-9Zn added with one or more trace amounts of In, Bi, Ag, Cu, or the like. Examples of the Sn system include Sn-Ag-Cu system (for example, Sn-3Ag-0.5Cu), Sn-Cu system (for example, Sn-0.7Cu), and Sn-Sb system (for example, Sn-5Sb).
[0057]
Also in this embodiment, the linear expansion coefficient is 24 × 10.^-6In the case of the epoxy filled resin 15 having a Young's modulus of 8 GPa at / ° C. and room temperature, almost no crack growth was observed in the power cycle test and the temperature cycle test.
[0058]
Hereinafter, the examination results under the constraint conditions from the performance, productivity, cost and the like will be described focusing on the functional aspects of each element of the first to third embodiments.
[0059]
First, the heat radiating substrate 4 is selected from Al, Al alloy or Al-carbon composite when weight reduction is important, and Cu, Cu alloy or Cu-carbon composite is selected when considering heat dissipation and small high performance. select. The heat dissipating substrate 4 has a thickness of 1 to 3 mm so that the heat resistance can be sufficiently reduced due to the spread of internal heat. In order to reduce warpage at the stage of mounting, the thickness of the Cu substrate may be 3 mm or more. Since the heat dissipation substrate 4 in the semiconductor power conversion device has a relatively large volume, the advantage of selecting lightweight Al is great. However, the linear expansion coefficient of Al (24 × 10^-6/ ° C.) Cu (17 × 10^-6/ ° C.), the difference in coefficient of linear expansion from the part increases. For this reason, when soldering a semiconductor chip and mounting a chip component or the like on the same substrate, the reliability of the solder joint is lowered as compared with the Cu substrate. However, the advantages of Al can be utilized by using only when there is no problem.
[0060]
The resin 15 employed in the embodiment of the present invention has a linear expansion coefficient of 30 × 10^-6Since the target is the / ° C. level, it can be said that this is a desirable direction for the Al heat dissipation substrate 4 in terms of preventing warpage of the heat dissipation substrate 4. In general, as the linear expansion coefficient increases, the amount of filler decreases, so the Young's modulus of the resin decreases and the amount of warpage is expected to be small. In addition, this thermal radiation board | substrate 4 is attached to a cooling fin.
[0061]
Next, the resin insulating layer 5 needs to have a low thermal resistance and a high insulating property. For this reason, a heat-resistant epoxy resin in which a filler is dispersed is used. The resin insulating layer 5 is applied by liquid coating or film-like resin (including resin prepreg) by heat-pressure molding or a roller. As the resin, an epoxy resin, a phenol resin, and other thermoplastic resins including polyamide imide and polyamide ether can be used. As the filler to be inserted into the resin insulating layer 5, an inorganic compound having high thermal conductivity such as silicon oxide, alumina, silicon nitride, boron nitride, and aluminum nitride is used. At this time, the thermal resistance of the resin insulating layer 5 can be reduced as the filler content increases, but the amount of filler that can be dispersed in the epoxy resin is limited, so that the filler content is usually 50 to 90 mass%. Use with a range. If the filling rate of the filler is 95 mass% or more, the filler cannot be filled uniformly. In this case, the thermal conductivity of the resin insulating layer 5 is in the range of 1 to 5 W / m · K. On the other hand, an effective method for reducing the thermal resistance of the resin insulating layer 5 is to make it thin. However, when the resin insulating layer 5 is thinned, the dielectric strength voltage is lowered correspondingly, and pinholes are easily generated in the resin insulating layer 5 and the reliability may be lowered. There is a limit to the lower limit of the thickness of the resin insulating layer 5, but 50 μm or more is necessary, although it depends on the required withstand voltage.
[0062]
Next, the electric circuit is made of a Cu conductor or an Al conductor, which is a heat diffusion plate 2 having a plate thickness of 0.7 mm or more, and is attached to the surface of the resin insulating layer 5. By setting the thickness of the electric circuit to 0.7 mm or more, sufficient heat spread can be obtained, and it also serves as a heat diffusion plate. Cu and Al conductors are easy to press even when they are thick, and are advantageous in terms of cost.
[0063]
As a result of conducting a power cycle test with the above structure, it was found that at a junction temperature Tj of 50 to 150 ° C., no breakage was observed even at 10,000 cycles, and almost no crack growth of solder was observed.
[0064]
FIG. 10 is a cross-sectional view of various heat diffusion plates that can be used in the semiconductor power module according to the present invention. When using a large chip or under severe environmental conditions, the use of a Cu plate as a heat diffusion plate is limited in reliability (chip destruction, chip cracking, solder life, etc.). Therefore, there are combinations of the following materials and the like as materials having a linear expansion coefficient close to that of the semiconductor chip and excellent in heat dissipation. That is, particle-dispersed Cu—Mo [for example, manufactured by Allied Material Co., Ltd.], Cu—Cu₂It is a combination of O [for example, L-COP catalog material of Hitachi Cable, NoC-1178, 02-4], Cu-Invar or composite fiber type Al-carbon, Cu-carbon, and the like. According to the data of L-COP, the linear expansion coefficient is (9-15) × 10^-6In the range of / ° C, the thermal conductivity can be adjusted in the range of about 120 to 240 W / m · K. Moreover, according to the catalog of Allied Material Co., Ltd., the coefficient of linear expansion of Cu—Mo is (7 to 13) × 10.^-6The thermal conductivity can be adjusted in the range of about 200 to 280 W / m · K in the range of / ° C. By integrating with a Cu plate processed during powder processing or with a Cu plate processed after powder processing to make a composite material with Cu, the thermal diffusion plate can be reduced in thermal expansion. By reducing the thermal diffusion plate to be soldered to the semiconductor chip, the reliability of the joint and the semiconductor chip interface peeling can be prevented, and a large chip and a structure that can withstand severe conditions can be provided. The linear expansion coefficient of the composite material can be controlled by increasing or decreasing the Cu ratio. A method of caulking and integrating the molded product with a Cu plate is also possible.
[0065]
FIG. 10A shows the above Cu-Mo, Cu-Cu.₂It is sectional drawing of the various thermal-diffusion board using O, Cu-invar, Cu-carbon fiber, etc. After connecting the chip 1 and the thermal diffusion plate 2 with the Pb-5Sn high-temperature solder 3, the thermal diffusion plate 2 and the Cu electrode pad 62 were connected with the lead-free solder 16 of Sn-3Ag-0.5Cu.
[0066]
10B to 10E are cross-sectional views of a heat diffusion plate 2 having a composite structure made by combining a particle dispersion type and a Cu plate. (B) is a caulking structure in the case of being thinly attached, and is a structure in which a particle dispersion material 202 is caulked by a caulking portion 203 on a Cu plate 201. (C) is a structure in which the particle dispersion material 205 is embedded in the Cu plate 204 punched by punching or the like. (D) shows a structure in which a Cu plate 206 and a particle dispersion material 207 are bonded together. (E) is a structure in which a previously processed Cu plate 208 is placed and the particle dispersion material 209 is integrated by powder processing. Their integrated thickness is 1 to 1.5 mm.
[0067]
FIG. 11 is a cross-sectional view of various heat diffusion plates having different shapes used in the semiconductor power module according to the present invention. Various functions can be provided by changing the shape of the heat diffusion plate. (A) is a structure that combines anisotropy with high thermal conductivity and low thermal expansion, and is a Cu-Mo dispersant, Cu-Invar dispersant, or Cu-Cu.₂This is a composite structure in which a plate 210 made of any one of O dispersants is sandwiched between Cu plates 211 and 212. Or it is the composite structure which pinched | interposed the Cu-Mo material or the invar material 210 with the Cu plates 211 and 212, and can produce the thermal-diffusion plate 2 with few curvature. By changing these mixing ratios, the characteristics can be freely changed. The composite structure may be made by a manufacturing method other than powder. (B) is a composite structure in which a plate 215 is sandwiched between laterally spread heat diffusion plates 213 and 214, which will be described later with reference to FIGS. 13 to 15, and a structure using the anisotropy of the material for improving performance. The plate 215 is Cu-Invar-Cu, Cu-Cu / Mo-Cu, Cu-Cu as in (A).₂If it is a combination of O-Cu, Cu-Cu / C-Cu, etc., the linear expansion coefficient can be controlled in the same manner, and the warpage is small. On the other hand, heat can be transferred from the chip 1 to Cu 213 and easily transmitted to the laterally expanded portion, and an anisotropic merit appears. (C)-(F) are particle-dispersed Cu-Mo, Cu-Cu₂The heat diffusion plates 216 to 219 made of O, Cu-Invar, etc. are changed in shape, and can be formed into a free shape during powder processing. It can also be made with a structure utilizing anisotropy. The structures (C) and (D) can be expected to improve the crack generation life of the solder 3 due to the positioning of the solder 3 and the decrease in rigidity. The structures (E) and (F) can be expected to adjust the thickness of the solder 3 and improve the crack generation life and crack propagation life of the solder 3. The linear expansion coefficient of some composite materials used for these combinations is α≈10 × 10 × 10.^-6It is / ° C., and the burden on Si such as residual stress after soldering, cooling and after cooling of the semiconductor chip 1 is small and causes no problem. Further, even after resin sealing, the burden on the Si chip is smaller than that of the Cu heat diffusion plate, and the structure can withstand a large chip and a severe test. Therefore, a semiconductor power module with higher reliability can be provided as compared with the Cu heat diffusion plate structure.
[0068]
FIG. 12 is a cross-sectional model showing a measure for improving the life of solder that can be used in the semiconductor power module according to the present invention. The purpose is to improve the thermal fatigue resistance of the solder and to connect the temperature hierarchy, and it is possible to prevent the strength from being lowered at a high temperature and to delay the crack progress. FIG. 12A shows a Pb-free Sn-3Ag-0.5Cu solder 302 paste mixed with about 10 to 30 vol% of Cu particles 303 and reflowed at a relatively high temperature of 260 to 280 ° C. . 18 is a Ti / Ni / Au thin film. Thereby, in the spherical Cu particles 303, as shown in FIG.₆Sn_FiveThe compound 304 grows at random and plays a role in preventing the progress of solder cracks. It is also possible to make a composite solder foil. Since the solder balls are integrated by rolling, only the Cu particles are dispersed in the solder. Cu₆Sn_FiveSince the compound 304 has a high melting point and is hard, even if a high temperature treatment of 250 ° C. such as secondary reflow is performed, even if the surrounding Sn-based solder is melted, the shape does not collapse. For this reason, it has the joining strength at high temperature by the elastic coupling | bonding by the connected compound and metal, and has ensured the intensity | strength which can endure the temperature at the time of secondary reflow. When a large amount of Cu particles are added, void formation tends to increase, which is undesirable. On the other hand, it has been confirmed that there is an effect of improving the strength by connection even at a 10 vol% level. FIG. 12C shows a mixture of Cu particles 303 with a composite solder foil based on Cu net 305 set. FIG. 12D is a cross-sectional model after soldering. Since Cu diffuses quickly into Sn at high temperatures, Cu in the solder and at the metallization interface₆Sn_FiveCompound 304 is formed, ensuring strength at high temperatures. Although this method has few voids, there is a restriction that solder is supplied as a solder foil. As a solder particle, Sn-3Ag-0.5Cu, Sn, Sn-0.7Cu, Sn- (5-10) Sb is a general composition as lead-free solder.
[0069]
With conventional Sn solder alone, it is difficult to establish a temperature hierarchy connection that can ensure reliability at high temperatures. This composite solder is used as a high-temperature solder for the temperature hierarchy. Therefore, the low-temperature solder here uses a general Sn-based, for example, Sn-3Ag-0.5Cu23, so that the temperature of the joint is high. Hierarchical connection is possible. As a result, the use area of the Cu heat sink can be expanded by improving the heat resistance, improving the temperature cycle resistance, and improving the thermal conductivity of the solder.
[0070]
In addition, although the example of Sn-3Ag-0.5Cu was shown as a representative composition of lead-free solder as a solder composition, it is the same also in Sn type, Sn-Sb type, Sn-Cu type, Sn-Ag type, etc. Results can be obtained.
[0071]
FIG. 13 is a sectional view of a semiconductor power module according to the fourth embodiment of the present invention, in which the heat dissipation of the semiconductor chip is improved. The same reference numerals as those in FIGS. 1, 8, and 9 denote the same components, and a duplicate description is avoided. This is a measure to improve the reliability and heat dissipation, which are weak points of the resin insulating substrate, and is a structure realized at low cost. Particle dispersion type Cu-Mo, Cu-Cu₂In the case of making with O, Cu-Invar or the like, if there is a mold, there will be no significant increase in cost. Therefore, the heat diffusion plate 2 is a laterally spreading heat diffusion plate 220 that has a concave structure with two open surfaces and achieves both improved heat dissipation and wire bonding. Since the resin insulating layer 5 under the chip 1 has a resin insulating film having poor thermal conductivity, it is difficult for heat to be directly transmitted from the bottom of the chip to the Cu heat dissipation substrate 4. On the other hand, heat is well transmitted to the heat diffusion plate 220. Therefore, the shape of the heat diffusion plate 220 is devised to provide a heat sink portion 221 around the chip, and a concave shape with a pair of side surfaces opened is used. As a result, the influence on the wire bond was eliminated, and the adverse effects on solderability, cleaning, and the like were reduced.
[0072]
FIG. 14 is a cross-sectional view of a semiconductor power module which is a fifth embodiment of the present invention and has improved heat dissipation from the surface of a semiconductor chip. If the structure of only the heat diffusion plate 220 of FIG. 13 has a small heat dissipation effect, as shown in FIG. 14, a plate 43 of ceramics (for example, Al2O3, AlN without metallization) excellent in thermal conductivity and inexpensive is placed on the upper surface. It is embedded in the resin with a heat sink 44 made of Cu, Al or the like applied. A fin (not shown) can be attached on the heat sink 44 of Cu, Al or the like. The heat diffusion plate 220, the ceramic plate 43, and the heat radiating plate 44 made of Cu, Al or the like are in good contact with the potting resin 15 in a state where the contact is good. As a result, the contact between the concave portion of the heat sink 221 and the ceramic plate 43 and between the ceramic plate 43 and the heat radiating plate 44 of Cu, Al or the like is firmly restrained by the surrounding resin 15 filled. A hole 45 at the center of the heat dissipation plate 44 made of Cu, Al or the like is for preventing void generation due to the filling resin 15. As described above, heat can be drawn from the upper side of the chip 1.
[0073]
FIG. 15 is a cross-sectional view and a plan view of a semiconductor power module which is a sixth embodiment of the present invention and has improved heat dissipation from the surface of a semiconductor chip. The same reference numerals as those in the above-described embodiment represent the same items, and redundant description is avoided. The concave portions of the heat diffusion plate 220 and the heat sink 221 are further raised, and the space between the concave portion and the high heat conductive ceramic plate 46 without metallization is firmly restrained with resin in the contact state as in FIG. The relationship between the recesses of the heat sink 221 and the arrangement of wire bonds is correctly illustrated in FIG. In the cross-sectional views shown in FIGS. 13, 14, and 15 (A), a structure rotated 90 degrees is illustrated for easy understanding.
[0074]
According to the above embodiment, the use of a filling resin having a linear expansion coefficient equal to or higher than that of solder, combined with an inexpensive heat dissipation substrate made of Al or Cu, a low-cost, reliable and long-life semiconductor power module. Can be provided. In addition, since the linear expansion coefficient of the filled resin is close to that of Al, an effect of preventing fatigue deterioration and disconnection of the ultrasonic wire bond portion of the Al wire can be expected.
[0075]
【The invention's effect】
  According to the present invention, without using an expensive AlN insulating substrate or Al2O3 insulating substrate, etc.Heat dissipation boardCan be used to provide a semiconductor power module with improved reliability and heat dissipation.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a semiconductor power module according to a first embodiment of the present invention.
FIG. 2 is a graph showing a model of temperature dependence of stress-strain curves of resin and solder.
FIG. 3 is a cross-sectional view of a main part for showing a mechanism of occurrence of cracking of a semiconductor chip in a resin-filled structure, and a graph showing a stress-strain curve model of the filled resin and solder.
[4A.]The graph which shows the relationship between a linear expansion coefficient and a Young's modulus at the time of changing the compounding quantity (Vol%) of a quartz filler to an epoxy resin.
[4B.]The graph which shows the physical property at the time of adding the rubber | gum flexible agent to the resin which does not contain the filler in the same epoxy resin system.
[4C.]The figure explaining the evaluation result which investigates the disconnection by the terminal part destruction of a board | substrate with respect to the compounding rate of a filler and rubber | gum.
[4D]The graph which shows the relationship between the Young's modulus in the filling resin 15, and a linear expansion coefficient.
FIG. 5 is a graph of linear expansion coefficient versus chip stress and linear expansion coefficient versus solder strain.
FIG. 6 is a graph of linear expansion coefficient versus chip stress and solder strain showing physical properties and reliability of filled resin.
FIG. 7 is a graph of analysis results showing the relationship between the Young's modulus of the resin and the restraint by the resin.
FIG. 8 is a cross-sectional view of a semiconductor power module according to a second embodiment of the present invention.
FIG. 9 is a sectional view of a semiconductor power module according to a third embodiment of the present invention.
FIG. 10 is a cross-sectional view of various heat diffusion plates that can be used in the semiconductor power module according to the present invention.
FIG. 11 is a cross-sectional view of various heat diffusion plates having different shapes that can be used in the semiconductor power module according to the present invention.
FIG. 12 is a cross-sectional model showing a plan for improving the life of solder that can be used in the semiconductor power module according to the present invention.
FIG. 13 is a cross-sectional view of a semiconductor power module with improved heat dissipation of a semiconductor chip as a fourth embodiment of the present invention.
FIG. 14 is a cross-sectional view of a semiconductor power module having improved heat dissipation from the surface of a semiconductor chip as a fifth embodiment of the present invention.
FIG. 15 is a cross-sectional view and a plan view of a semiconductor power module having improved heat dissipation from the surface of a semiconductor chip as a sixth embodiment of the present invention.
[Explanation of symbols]
  DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip, 2,220 ... Thermal diffusion plate, 201, 204, 206, 208 ... Cu thermal diffusion plate, 202, 205, 207, 209 ... Particle dispersion material, 210, 215 ... Invar material, 211-214, 216 to 219 ... Cu plate, 229 ... heat sink, 3, 7, 12, 16, 17 ... solder, 4 ... heat dissipation substrate, 43, 46 ... ceramic plate, 44 ... heat dissipation plate such as Cu, Al, etc. 5 ... resin insulation layer , 6 ... Electric circuit (Cu foil conductor), 61 ... Cu terminal, 62 ... Cu pad, 8 ... Metal thin wire, 9, 13 ... External connection terminal, 10 ... IC, 11 ... Control board, 14 ... Case, 15 ... Filling (Epoxy) resin.

Claims (15)

  A heat dissipating board having a resin insulating layer, and a metal heat diffusion plate bonded to the resin insulating layer of the heat dissipating board with an adhesive or joined to an electric circuit of a Cu foil conductor formed on the resin insulating layer by soldering And a semiconductor chip having a metallized surface soldered to the heat diffusion plate, a case for housing these, and a resin filled in the case, the linear expansion coefficient of the resin being determined by the solder The thermal diffusion plate includes a sintered formed body obtained by mixing and sintering Cu and a powder of a low expansion material, and a Cu plate connected to the sintered formed body. Semiconductor power module. 2. The semiconductor power module according to claim 1, wherein the resin has a linear expansion coefficient of (20 to 45) × 10 ⁻⁶ / ° C.   2. The heat dissipation substrate according to claim 1, wherein the heat dissipation substrate includes a substrate made of Cu or Al or an alloy containing them, and a resin insulating layer bonded or applied to the substrate. The heat diffusion plate includes Cu, Cu alloy, Cu, and the like. Cu2O, Cu-Mo, or Cu-Invar powder mixed structure, or sandwich structure with this molded body as the core Cu- (Cu / Cu2O) -Cu, Cu- (Cu / Mo) -Cu A semiconductor power module having an anisotropic structure of Cu- (Cu / Invar) -Cu and Cu- (Cu / C) -Cu.   2. The semiconductor power module according to claim 1, wherein the heat diffusion plate has a structure in which the heat diffusion plate is sintered to have a concave cross section, and the semiconductor chip is placed in the concave portion.   2. The semiconductor power module according to claim 1, wherein Young's modulus of the resin at 15 to 20 [deg.] C. is 1 to 12 GPa.   The semiconductor power module according to claim 1, wherein the glass transition temperature Tg of the resin is 150 ° C. or higher.   2. The semiconductor power module according to claim 1, wherein the element forming surface of the semiconductor chip is covered with a resin having a Young's modulus lower than that of the resin by 0.01 to 1 mm.   2. The semiconductor power module according to claim 1, wherein the element forming surface of the semiconductor chip is covered with a silicone gel in an amount of 0.01 to 1 mm.   2. The semiconductor power module according to claim 1, wherein a flexibilizing agent is added to the resin in a range of 5 to 15 mass%.   2. The semiconductor power module according to claim 1, wherein the Young's modulus of the resin at 15 to 20 ° C. is 3 to 10 GPa. A heat dissipating board having a resin insulating layer, and a metal heat diffusion plate bonded to the resin insulating layer of the heat dissipating board with an adhesive or joined to an electric circuit of a Cu foil conductor formed on the resin insulating layer by soldering And a semiconductor chip having a metallized surface soldered to the heat diffusion plate, a case for housing them, and a resin filled in the case, wherein the heat dissipation substrate is made of Cu or Al or A substrate made of an alloy containing them, and a resin insulating layer adhered or applied to the substrate, the thermal diffusion plate is a sintered formed body obtained by mixing and sintering Cu and a powder of a low expansion material, The composite is provided with a Cu plate in which the sintered compact is fixed, pressure-bonded, or integrated, and the linear expansion coefficient of the resin is (20 to 45) × 10 ⁻⁶ / ° C., and 15 to 20 At ℃ A semiconductor power module, wherein the resin has a Young's modulus of 1 to 12 GPa.   The semiconductor power module according to claim 11, wherein the glass transition temperature Tg of the resin is 150 ° C. or higher.   12. The semiconductor power module according to claim 11, wherein the element forming surface of the semiconductor chip is covered with a resin having a Young's modulus lower than that of the resin by 0.01 to 1 mm.   12. The semiconductor power module according to claim 11, wherein a flexibilizer is added to the resin in a range of 5 to 15 mass%.   The semiconductor power module according to claim 11, wherein the Young's modulus of the resin at 15 to 20 ° C is 3 to 10 GPa.

Images