JP2008181922A - Thermally conductive substrate, manufacturing method thereof, and semiconductor device using the thermally conductive substrate - Google Patents

Abstract

A thermal conductive substrate using an insulating resin sheet that reduces warping, peeling, and cracking is provided.
A heat conductive insulating resin sheet 3 provided between a metal base plate 2 and an electrode 4 of a heat conductive substrate is provided with a wall portion 6 having a thickness of 400 μm or less in close contact with a side surface of the electrode, on the resin sheet. Is provided with a glass epoxy resin spacer 8 in close contact with the wall portion. The spacer has a smaller coefficient of thermal expansion than the resin sheet. The wall portion of the insulating sheet is formed by allowing the resin sheet material to flow and cure in the gap between the electrode and the spacer by a hot press.
[Selection] Figure 1

Description

  The present invention relates to a heat conductive substrate using a heat conductive insulating resin sheet, a manufacturing method thereof, and a semiconductor device using the heat conductive substrate.

  As a conventional semiconductor device and heat conductive substrate, there is a lead frame integrated with a semi-cured heat conductive resin sheet member. This is manufactured by a method in which a lead frame is pressed against a semi-cured thermally conductive resin sheet member by heating and pressing, and the lead frame is embedded in the thermally conductive resin sheet member (for example, Patent Document 1).

  In addition, an insulating layer is provided on a metal base plate, a conductive pattern is disposed on the insulating layer, and a circuit element is mounted on the conductive pattern using this substrate and wired with a thin metal wire. A resin-sealed hybrid integrated circuit device has also been proposed (for example, Patent Document 2).

JP 2002-270744 A JP 2003-318333 A

  In a semiconductor device or a high thermal conductive substrate, as described in Patent Document 1, when a lead frame is heated and pressed against a heat conductive resin sheet member, the resin sheet member has a sufficient thickness and high fluidity. In this case, the resin of the resin sheet member flows into the opening of the lead frame with a uniform thickness.

  The same applies to the case where a copper pattern to be an electrode having a thickness of 0.3 mm or more is pressed into a thermally conductive resin sheet by heating and pressing, and the space between the electrodes on the metal base plate is high. Filled with resin sheet material.

  A high thermal conductivity substrate with such a structure is then used for the heat history in the semiconductor device manufacturing process (heating and cooling during soldering of the chip, resin sealing such as potting and molding), and heat cycle after product completion. It receives thermal stress due to thermal history. Due to the difference in thermal expansion between the electrode material and the resin sheet material and the stress caused by the warp generated on the metal base plate, the resin sheet peels off from the metal base plate and cracks, and the heat conduction to the metal base plate is significantly hindered. There was a problem that.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a heat conductive substrate that does not cause warping of the substrate and peeling or cracking of the resin sheet, a manufacturing method thereof, and a heat conductive substrate. It is providing the semiconductor device using this.

  The heat conductive substrate according to the present invention is a heat conductive substrate provided with a heat conductive insulating resin sheet between a metal base plate and an electrode, wherein the heat conductive insulating resin sheet extends along a side surface of the electrode. A wall portion that is in close contact with the side surface is provided.

  Also, the method for manufacturing a heat conductive substrate according to the present invention provides a heat conductive insulating material on a metal base plate in order to manufacture a heat conductive substrate having a heat conductive insulating resin sheet between the metal base plate and the electrode. A step of providing a resin sheet, a step of providing an electrode on the thermally conductive insulating resin sheet, a step of providing a spacer surrounding the side surface of the electrode with a gap on the thermally conductive insulating resin sheet, the electrode and And a step of pressurizing and heating at least one of the thermally conductive insulating resin sheet and the spacer by heating the spacer to the thermally conductive insulating resin sheet with a heating press.

  Furthermore, a semiconductor device according to the present invention uses the above-described heat conductive substrate.

  According to this invention, the side surface of the electrode can be covered with the wall portion rising from the heat conductive insulating sheet, and the effect of relaxing the stress generated in the substrate due to the thermal history such as heat cycle can be obtained, and the warpage and heat of the substrate can be obtained. Peeling and cracking of the conductive insulating resin sheet can be prevented.

Embodiment 1 FIG.
FIG. 1 is a schematic sectional side view showing a heat conductive substrate 1 of the present invention. The heat conductive substrate 1 includes a metal base plate 2, a heat conductive insulating resin sheet 3 provided on the upper surface of the metal base plate 2, and an electrode 4 provided on the upper surface of the heat conductive insulating resin sheet 3. Yes. The thermally conductive insulating resin sheet 3 includes a wall portion 6 that extends along the side surface 5 so as to surround the electrode 4 and is in close contact with the side surface 5 of the electrode 4. On the thermally conductive insulating resin sheet 3, a spacer 8 is provided that is in close contact with the wall portion 6 that is in close contact with the side surface 5 around the electrode 4.

  The metal base plate 2 is a plate-like member made of a metal material having good heat conductivity such as aluminum.

The thermally conductive insulating resin sheet 3 has a thermal conductivity of 3 W / mK or more and is made of a thermosetting resin. The resin of the heat conductive insulating resin sheet 3 is at least one selected from the group consisting of, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a liquid phenol resin. The thermally conductive insulating resin sheet 3 is filled with a thermally conductive inorganic powder filler containing boron nitride as a filler. The filling rate is preferably 50 to 80% by volume. When the filling rate is lower than this range, the thermal conductivity is insufficient, and when it is high, the viscosity as the resin material is too large. The thermally conductive insulating resin sheet 3 preferably has a viscosity in the range of 10 ⁵ to 10 ⁸ Pa · s at 100 ° C. If the viscosity is lower than this range, the fluidity is large, and the metal base plate 2 and the electrode 4 cannot be held at appropriate positions. If the viscosity is high, the wall portion of the thermally conductive insulating resin sheet 3 to be described later is adequate. Not formation.

  Moreover, the thermosetting resin composition may further contain other components. For example, it is preferable to include a curing agent and / or a curing accelerator, and for example, a bisphenol A type novolak resin can be used as the curing agent, and imidazole can be used as the curing accelerator. Furthermore, additives such as a coupling agent, a dispersant, a colorant, and a release agent can be further included as necessary.

  The electrode 4 is made of a highly conductive metal such as copper and has a thickness of 0.5 mm, for example, and is formed on the thermally conductive insulating resin sheet 3 in a desired pattern.

  The wall portion 6 of the thermally conductive insulating resin sheet 3 is provided in close contact with the entire side surface 5 of the electrode 4, the height is the same as the thickness of the electrode 4, and the thickness is 10 to 400 μm. The thickness of the wall portion 6 is preferably 20 to 100 μm. If the thickness of the wall portion 6 is smaller than the range of 20 to 100 μm, the wall portion 6 does not necessarily have a sufficient coating and holding action on the side surface 5 of the electrode 4, and if it is large, cracks and peeling occur on the wall portion 6.

  The spacer 8 is made of glass epoxy resin, but can be made of prepreg.

  Such a heat conductive substrate 1 is manufactured by the steps shown in FIGS. That is, in FIG. 2, the heat conductive insulating resin sheet 3 is placed on the upper surface of the metal base plate 2, and is pressed from above and below with a vacuum laminator or a press to adhere to each other.

  Next, as shown in FIG. 3, the electrodes 4 are arranged in a predetermined pattern on the upper surface of the thermally conductive insulating resin sheet 3 on the metal base plate 2. A spacer 8 having a side surface 7 is provided on the heat conductive insulating resin sheet 3 so that a gap 9 is formed between the side surface 5 of the electrode 4 and the side surface 7 of the spacer 8. 9 to be surrounded by the spacer 8. The size of the gap 9, that is, the distance between the side surface 5 of the electrode 4 and the side surface 7 of the spacer 8 is 10 to 400 μm in view of the thickness of the wall portion 6, but is preferably 20 to 100 μm. The thickness of the spacer 8 is preferably equal to the thickness of the electrode 4. The planar shape of the spacer 8 corresponds to the shape of the electrode 4 and has a complementary shape that complements each other so that a substantially uniform gap 9 can be formed on the entire circumference of the electrode 4.

  Next, the assembly shown in FIG. 3 is placed between the press plates 11 and 12 of the heating press 10 as shown in FIG. 4 and heated while applying pressing force from above and below as shown by the arrows, and the electrodes 4 and The spacer 8 is heated under pressure. By pressurizing and heating by the heating press 10, first, the electrode 4 and the spacer 8 are pressed against the heat conductive insulating resin sheet 3 by pressure, and a part of the material of the heat conductive insulating resin sheet 3 is formed between the electrode 4 and the spacer 8. It flows and is pushed into the gap 9 between them. The pressed portion is a wall portion 6 that is in close contact with the side surface 5 of the electrode 4, the side surface 7 of the spacer 8, and the press plate 11 and that is integrally continuous from the heat conductive insulating resin sheet 3. When the spacer 8 that cannot form the gap 9 is used, not only the necessary wall portion 6 cannot be formed, but also a very high dimensional accuracy is required for the spacer 8 and the electrode 4 in the manufacturing process that easily generates thermal stress. Will increase the cost.

  The heat conductive substrate 1 shown in FIG. 1 can be manufactured by the manufacturing method described above. Thus, according to this invention, since the heat conductive insulating resin sheet 3 is provided with the wall part 6 extended along the side surface of the electrode 4 and closely_contact | adhered to this side surface, the metal base plate 2, the electrode 4, However, it is possible to obtain the heat conductive substrate 1 in which the warp of the heat conductive substrate 1 and the peeling or cracking of the heat conductive insulating resin sheet 3 do not occur. Further, by providing the spacer 8, the warp of the heat conductive substrate 1 can be further suppressed, and the peeling of the electrode 4 and the crack of the heat conductive insulating resin sheet 3 can be more reliably prevented (see FIG. 7).

  FIG. 5 shows a semiconductor device 15 using the heat conductive substrate 1 of the present invention shown in FIG. In the figure, the heat conductive substrate 1 of FIG. 1 has a semiconductor chip 16 and electrode terminals 17 soldered on the electrodes 4, and wiring by wiring wires 18 is applied. A sealing resin 20 is applied on the metal base plate 2. Molded and resin-sealed components such as the semiconductor chip 16, electrode terminal 17, wiring wire 18 and the like. The metal base plate 2 of the heat conductive substrate 1 is bonded onto the heat radiating fins 19.

  As described above, the heat conductive substrate 1 of the present invention can be used for manufacturing a semiconductor device 15 such as a power module by resin sealing in the same manner as a known heat conductive substrate, and the reliability of the semiconductor device 15 is improved. improves. Although the sealing resin 20 is not limited to a thermosetting resin or a thermoplastic resin, it is preferable to seal with a thermosetting resin because the thermoplastic resin has poor adhesion. The sealing means includes a transfer mold and a liquid resin potting, but is not particularly limited.

Embodiment 2. FIG.
In the heat conductive substrate 1 of FIG. 1, a prepreg sheet can be used alone as the spacer 8 instead of the glass epoxy resin, or a combination of a prepreg sheet and a glass epoxy resin sheet can be used. That is, the spacer 8 can be made of at least one of a glass epoxy resin and a prepreg.

  When combining a glass epoxy material and a prepreg sheet, when the electrode 4 is 0.5 mm thick, for example, a composite structure in which a 0.4 mm thick glass epoxy material sheet and a 0.1 mm thick prepreg sheet are superposed. Use spacers. As a result, the prepreg sheet has fluidity similar to the heat conductive insulating resin sheet 3 at the time of heating and pressurizing at the time of manufacturing the substrate, and the wettability or familiarity with the heat conductive insulating resin sheet 3 is improved, and the adhesiveness is improved. An improving effect is obtained.

  Further, by making the melt viscosity of the prepreg sheet smaller than the melt viscosity of the heat conductive insulating resin sheet 3, the wall portion 6 of the heat conductive insulating resin sheet 3 is formed by pressurizing and heating the heating press 10 as shown in FIG. 4. When flowing into the gap 9 (FIG. 3) between the electrode 4 and the spacer 8, the contact portion between the electrode 4, the spacer 8, and the wall portion 6 becomes more intimate, and the effect of suppressing the warp of the heat conductive substrate 1 Becomes larger.

Embodiment 3 FIG.
In the heat conductive substrate 1 of FIG. 1, a spacer made of an epoxy resin or glass epoxy resin having a smaller thermal expansion coefficient than that of the heat conductive insulating resin sheet 3 can also be used as the spacer 8. As the epoxy resin having a small thermal expansion coefficient, for example, a highly filled inorganic powder having a small thermal expansion coefficient such as silica is used. By using a resin with a small coefficient of thermal expansion, the thermal expansion coefficient of the spacer is no longer anisotropy like that of glass epoxy resin, and the thermal expansion coefficient in the thickness direction is smaller than that of glass epoxy resin. It leads to improvement.

  By making the thermal expansion coefficient of the spacer 8 provided between the electrodes 4 smaller than the thermal expansion coefficient of the heat conductive insulating resin sheet 3, the warp of the heat conductive substrate 1 can be suppressed, and the stress generated by the warp can be reduced. The peeling of 4 and the crack of the heat conductive insulating resin sheet 3 are suppressed, and the reliability with respect to thermal shocks, such as a heat cycle and reflow, improves.

  In addition, by using a material having a thermal expansion coefficient smaller than that of the heat conductive insulating resin sheet 3 as the material of the spacer 8, the heat conductive insulating resin sheet between the electrodes 4 is used as in the example described in Patent Document 1. As compared with the case where the heat conduction substrate is buried, the stress after the production of the heat conduction substrate is relieved, and a heat conduction substrate in which warpage is small and cracks are not generated due to a heat history such as a heat cycle can be obtained.

Embodiment 4 FIG.
In the heat conductive substrate 1 shown in FIG. 1, the heat conductive insulating resin sheet 3 and the spacer 8 can be maintained in a semi-cured state without being completely cured. This can be realized by adjusting the time and temperature of the pressure heating process shown in FIG.

  In this case, when the heat conductive substrate 1 is manufactured, in the pressure heating process applied to the heat conductive insulating resin sheet 3 or the spacer 8, the pressure heating process is performed in a state where the heat conductive insulating resin sheet 3 and the spacer 8 are semi-cured. Stop it. When such a heat conductive substrate 1 is used, a semiconductor chip 16, electrode terminals 17, wiring wires 18, heat radiation fins 19, etc. are mounted on the heat conductive substrate 1 and sealed with a sealing resin 20 as shown in FIG. When the sealing resin 20 is cured by heating, the heat is used to cure simultaneously.

  Thus, as the heat conductive substrate 1, at least one of the heat conductive insulating resin sheet 3 and the spacer 8 can be semi-cured. Further, when a resin-encapsulated semiconductor device is manufactured using the heat conductive substrate 1, the semi-cured thermally conductive insulating resin sheet 3 and the spacer 8 are cured with the sealing resin 20 during resin sealing. At the same time, it is completely cured to complete the semiconductor device. Thereby, the effect that the adhesive strength of the interface between the heat conductive insulating resin sheet 3 and the sealing resin 20 and between the spacer 8 and the sealing resin 20 becomes strong is obtained.

Embodiment 5. FIG.
FIG. 6 shows a heat conductive substrate 21 from which the spacer 8 is removed from the heat conductive substrate 1 of FIG. The heat conductive substrate 21 is obtained by removing the spacer 8 after curing at least one of the heat conductive insulating resin sheet 3 and the spacer 8 by the pressure heating process of FIG. Other structures and manufacturing methods are the same as those described with reference to FIGS.

  According to this heat conductive substrate 21, since the spacer 8 of FIG. 1 is removed, it cannot be said that the heat conductive substrate 21 is superior to the heat conductive substrate 1 of FIG. Since the conductive insulating resin sheet 3 includes the wall portion 6 that extends along the side surface of the electrode 4 and is in close contact with the side surface, the integrity of the metal base plate 2 and the electrode 4 is ensured, and still heat It is possible to obtain the heat conductive substrate 1 in which warpage of the conductive substrate 1 and peeling or cracking of the heat conductive insulating resin sheet 3 hardly occur.

  FIG. 7 shows the warpage of the metal base plate 2 having a length of about 50 mm of the heat conductive substrate having the copper electrode 4 having a thickness of 0.5 mm with respect to the warpage amount (μm) and the peeling rate (%) of the heat conductive substrate. The results of measuring the amount and the peeling rate are tabulated for the present invention as shown in FIG. 1 and a comparative example according to the prior art. The amount of warpage is important for reducing the thermal resistance between the heat conduction substrate 1 and the heat dissipation fin 19 when the heat dissipating fins 19 are attached to the metal base plate 2 side of the heat conduction substrate 1 and is necessary because the amount of warpage of the heat conduction substrate 1 is small. This is important in that the amount of grease can be suppressed, the overall thermal resistance can be reduced, and a power module with better heat dissipation can be obtained.

  As is apparent from the table of FIG. 7, the warpage amount of the heat conductive substrate 1 of FIG. 1 manufactured by the manufacturing method of the present invention is the case when the thermal expansion coefficient of the spacer 8 of glass epoxy resin is 14 ppm (Invention 1). Was about −5 μm and the peel rate was 0. When the thermal expansion coefficient of the spacer 8 was 25 ppm (Invention 2), the peel rate was about 20 μm and the peel rate was 0%.

  When the spacer 8 is a prepreg and the thermal expansion coefficient is 14 ppm (Invention 3), the amount of warpage is about −5 μm and the peeling rate is 0%, and the thermal expansion coefficient of the spacer 8 is 25 ppm (Invention 3). In 4), the amount of warpage was about 20 μm, and the peel rate was 0%. When an epoxy resin was used as the spacer 8 and the thermal expansion coefficient was 16 ppm (Invention 5), the warpage amount% and the peeling rate were 0.

  As a sample for comparison with the heat conductive substrate 1 of the present invention, as described in Patent Document 1, instead of the spacer, the heat conductive insulating resin sheet 3 is raised between the electrodes to be flush with each other ( In Comparative Example 1), the amount of warpage is about 100 μm, and the peel rate is as high as 30% due to stress due to warpage, and about 30% of the manufactured substrate is part of the substrate with the electrode 4 and the thermally conductive insulating resin sheet 3. And cracks occurred in the resin sheet.

  Further, when the heat conductive substrate was manufactured without forming the spacer 8 and the wall portion 6 of the present invention (Comparative Example 2), the warpage amount was about 50 mm and the peeling rate was 20%. About 20% of the substrate thus formed had peeling of the electrode material and the resin sheet on one part of the substrate and cracks in the resin sheet. When the electrode material is pressed, the heat conductive substrate of Comparative Example 2 is pressed at a low pressure such as 10 kgf / cm 2 or a resin sheet having low fluidity is used. It was manufactured so as not to be embedded in the conductive insulating resin sheet 3.

  The various embodiments described above and their individual features can be used in combination with each other as appropriate.

It is a schematic sectional drawing which shows embodiment of the heat conductive board | substrate of this invention. It is a schematic sectional drawing which shows the state which provided the heat conductive insulating resin sheet on the metal base plate of the heat conductive board | substrate of FIG. It is a schematic sectional drawing which shows the state which provided the electrode and the spacer on the heat conductive insulating resin sheet of FIG. FIG. 4 is a schematic cross-sectional view showing a state where the heat conducting substrate of FIG. It is a schematic sectional drawing which shows the resin sealing type semiconductor device manufactured using the heat conductive board | substrate of FIG. It is a schematic sectional drawing which shows another embodiment of the heat conductive board | substrate of this invention. It is a table | surface which shows the curvature amount and peeling rate of the heat conductive substrate of this invention compared with a prior art.

Explanation of symbols

  1, 21 Thermal conductive substrate, 2 Metal base plate, 3 Thermal conductive insulating resin sheet, 4 Electrode, 5 Side surface, 6 Wall part, 7 Side surface, 8 Spacer, 9 Gap, 10 Heating press, 11 Press plate, 15 Semiconductor device , 16 Semiconductor chip, 17 Electrode terminal, 18 Wiring wire, 19 Radiation fin, 20 Sealing resin.

Claims (14)

In the heat conductive substrate provided with a heat conductive insulating resin sheet between the metal base plate and the electrode,
The thermally conductive substrate, wherein the thermally conductive insulating resin sheet includes a wall portion that extends along the side surface of the electrode and is in close contact with the side surface.   The heat conductive substrate according to claim 1, wherein the wall portion of the heat conductive insulating resin sheet has a thickness of 20 to 100 μm.   The heat conductive substrate according to claim 1 or 2, further comprising a spacer provided in close contact with the heat conductive insulating resin sheet and in close contact with the wall portion.   4. The thermal conductive substrate according to claim 3, wherein the spacer has a thermal expansion coefficient smaller than that of the thermal conductive insulating resin sheet.   The heat conductive substrate according to claim 3, wherein the spacer is at least one of a glass epoxy resin and a prepreg.   6. The thermal conductive insulating resin sheet is at least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin and liquid phenol resin. The heat conductive substrate as described.   The thermally conductive substrate according to any one of claims 1 to 6, wherein the thermally conductive insulating resin sheet is filled with a thermally conductive inorganic powder filler containing boron nitride as a filler. The heat conductive substrate according to any one of claims 1 to 7, wherein the heat conductive insulating resin sheet has a viscosity in a range of 10 ⁵ to 10 ⁸ Pa · s at 100 ° C. A method of manufacturing a heat conductive substrate provided with a heat conductive insulating resin sheet between a metal base plate and an electrode,
Providing a thermally conductive insulating resin sheet on the metal base plate;
Providing an electrode on the thermally conductive insulating resin sheet;
Providing a spacer surrounding the side surface of the electrode with a gap on the thermally conductive insulating resin sheet;
A heat comprising: a curing step in which at least one of the heat conductive insulating resin sheet and the spacer is at least semi-cured by pressurizing and heating the electrode and the spacer to the heat conductive insulating resin sheet by a heating press. A method for manufacturing a conductive substrate.   10. The method for manufacturing a heat conducting substrate according to claim 9, wherein the size of the gap between the electrode and the spacer is 20 to 100 [mu] m.   The method for manufacturing a heat conductive substrate according to claim 9 or 10, wherein the heat conductive insulating resin sheet is filled with a heat conductive inorganic powder filler containing boron nitride as a filler.   12. The method according to claim 9, wherein after the step of semi-curing at least one of the thermally conductive insulating resin sheet and the spacer, the resin is completely cured simultaneously with the curing of the sealing resin at the time of resin sealing. The manufacturing method of the heat conductive board | substrate of description.   The method for manufacturing a heat conductive substrate according to claim 9, further comprising a step of removing the spacer after the curing step.   A semiconductor device using the heat conductive substrate according to claim 1.

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