JP2012146813A - Method of manufacturing substrate for mounting electronic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To braze a ceramic substrate to a heat sink well, in a method of manufacturing a substrate for mounting an electronic element in which the layers containing an aluminum heat sink are collectively brazed.SOLUTION: In the method of a manufacturing a substrate for mounting an electronic element, a circuit layer (13) of metal is overlaid on one surface of a ceramic substrate (11) through a solder (12), while a thermal stress relaxing material (14) of aluminum and a heat sink (15) of aluminum are arranged in stacked manner on the other surface through solders (16)(17), for temporarily assembling a laminate (10) which are collectively brazed simultaneously. Brazing is carried out on the laminate (10) that has been temporarily assembled under such condition as a wettability degradation material (20) which degrades wettability of the solder is stuck to the periphery of a junction part (18) between the ceramic substrate (11) and the thermal stress relaxing material (14).

Description

  The present invention relates to a method for manufacturing an electronic element mounting substrate in which heat dissipation performance is provided by brazing a heat sink to a ceramic substrate.

  In the present specification and claims, the term “aluminum” is used to include both aluminum and its alloys.

  In an electronic element mounting substrate, in order to efficiently dissipate heat generated by a chip, a heat sink may be brazed to the surface of the ceramic substrate opposite to the element mounting surface (see Patent Document 1).

  FIG. 1 shows an example of this type of electronic device mounting substrate. An aluminum circuit layer (13) is brazed to one surface of a ceramic substrate (11), which is an electronic device mounting surface, and aluminum is mounted to the other surface. An aluminum heat sink (15) is brazed via the layer (14).

  As the aluminum constituting the heat sink (15), an Al—Mn alloy or an Al—Fe alloy is used to maintain strength. In addition, if the ceramic substrate (11) and the heat sink (15) made of high-strength aluminum alloy are brazed directly, peeling of the joints and cracking of the ceramic substrate will occur during the cooling cycle due to heat generated during energization and cooling during non-energization. Therefore, by causing the soft aluminum layer (14) to intervene, the thermal stress generated at the joint is relaxed to suppress the occurrence of peeling. Further, in order to increase stress due to structural changes due to weight reduction and to improve the thermal cycle life, further improvement in durability of the bonding interface has been desired.

JP 2004-153075 A

  When manufacturing the electronic device mounting substrate, the aluminum circuit layer (13) and the ceramic substrate (11), the ceramic substrate (11) and the aluminum layer (14), the aluminum layer (14) and the heat sink ( 15) brazing materials (12), (16), and (17) are placed between them, the laminated body (10) is temporarily assembled, and the temporarily assembled laminated body (10) is heated to braze at three locations. Is performed at once.

  At the time of this brazing, elements derived from the aluminum alloy constituting the heat sink (15), such as Mn and Fe, are separated into the molten brazing material (16) and mixed with the ceramic substrate (11) and the aluminum layer (14). It was thought that it penetrates into the joint interface. In addition, brazing and durability of the joint interface are further improved so that a good joining state between the heat sink (15) and the aluminum layer (14) is maintained even when a larger thermal stress is applied than before. It is desired.

  In view of the above-described technical background, the present invention provides a technique for achieving further improvements in brazing and durability of the bonding interface in a method for manufacturing an electronic element mounting substrate that collectively brazes each layer including an aluminum heat sink. It is to provide.

  That is, this invention has the structure as described in following [1]-[10].

[1] A circuit layer made of metal is disposed on one surface of a ceramic substrate with a brazing material interposed therebetween, and a thermal stress relaxation material made of aluminum and a heat sink made of aluminum are respectively brazed on the other surface. Is a method of manufacturing a substrate for mounting an electronic device in which a laminated body is temporarily arranged by stacking through, and these are simultaneously brazed together,
Electronic device mounting characterized in that brazing is performed in a state where a wettability reducing material that lowers the wettability of the brazing material is adhered around the joint between the ceramic substrate and the thermal stress relaxation material in the temporarily assembled laminate Manufacturing method for industrial use.

  [2] In the laminate in which the corner portion is formed by the outer circumferential surface of the thermal stress relaxation material and the other surface of the ceramic substrate, the outer circumferential surface of the thermal stress relaxation material and the other of the ceramic substrate including the corner portion. 2. The method for manufacturing a substrate for mounting an electronic element according to 1 above, wherein brazing is performed in a state where a wettability reducing material is adhered to the surface of the electronic element.

  [3] The thermal stress relaxation material is a punching metal having a through hole, and brazing is performed in a state where a wettability reducing material is attached to a peripheral surface of the through hole in the temporarily assembled laminated body. The manufacturing method of the board | substrate for electronic element mounting of description.

  [4] The method for manufacturing an electronic element mounting substrate according to any one of [1] to [3], wherein the wettability reducing material is at least one of boron nitride and carbon.

  [5] The method for manufacturing a substrate for mounting an electronic element according to [4], wherein the wettability reducing material is adhered by applying a dispersion in which the wettability reducing material is dispersed in an organic dispersion medium.

  [6] The method for manufacturing an electronic element mounting substrate as described in 5 above, wherein a binder is added to the dispersion.

  [7] The method for manufacturing an electronic element mounting substrate according to any one of [1] to [3], wherein the wettability reducing material is a resin in which carbon which is a decomposition product by heating remains at an adhesion position at 560 ° C.

  [8] The method for manufacturing a substrate for mounting an electronic element according to [7], wherein the resin is an adhesive made of at least one of an epoxy resin, a phenol resin, and an acrylic resin.

  [9] The method for manufacturing an electronic element mounting substrate as described in any one of [1] to [8] above, wherein the wettability reducing material is applied after temporarily assembling the laminate.

  [10] A wettability reducing material is applied to the edge of one or both opposing surfaces of the ceramic substrate and the thermal stress relaxation material before temporary assembly, and the laminated body is temporarily assembled together with other members, and temporarily assembled. 9. The method for manufacturing a substrate for mounting an electronic element according to any one of 1 to 8 above, wherein the laminate is pressed in the laminating direction to discharge the wettability reducing material to the outside from the laminating interface and adhere to the periphery of the joint.

  According to the method for manufacturing a substrate for mounting an electronic device according to [1] above, since the wettability reducing material is attached around the joint portion between the ceramic substrate and the thermal stress relaxation material of the temporarily assembled laminate, At the time of brazing, an element derived from the brazing material or heat sink melted around the joint is repelled. For this reason, the entry of the element detached from the heat sink into the brazing material is prevented, and it is not possible for the element to enter the bonding interface by mixing into the brazing material, thus achieving good brazing without reducing the brazing property of the element. Is done. As a result, even when heat generation and cooling are repeated in a usage environment of the substrate electronic device mounting substrate and a very large thermal stress is applied, peeling of the bonding interface is suppressed, and durability of the bonding interface in a cooling cycle is improved.

  According to the invention described in [2] above, the laminate in which the size of the thermal stress relaxation material is smaller than that of the ceramic substrate and the corner portion is formed by the outer peripheral surface of the thermal stress relaxation material and the other surface of the ceramic substrate. The effect described in [1] above can be obtained.

  According to the invention described in [3] above, since the wettability reducing material is attached to the peripheral surface of the through hole of the punching metal used as the thermal stress relaxation material, the element derived from the heat sink is brazed through the through hole. It is prevented from being mixed in.

  According to the invention described in [4] above, good brazing can be achieved due to the boron nitride and / or carbon wettability reducing effect.

  According to the invention described in [5] above, since boron nitride and / or carbon is applied as a dispersion liquid dispersed in an organic dispersion medium, it can be easily applied to a predetermined position and the amount of adhesion can be reduced. Adjustment is also easy.

  According to the invention described in [6] above, since the viscosity of the dispersion is increased by the binder, the liquid does not easily drip at the time of application, and a required amount of the wettability reducing material can be easily attached.

  According to the invention described in [7] above, at 560 ° C., the adhered resin remains as carbon which is a thermal decomposition product at the adhesion position, so that good brazing is achieved due to the effect of reducing the wettability of carbon. Can be achieved.

  According to the invention described in [8] above, the handling property of the laminate is improved by the temporary fixing effect by the adhesive before brazing, and the wettability lowering effect of the carbon which is the thermal decomposition product at the time of brazing is increased. Good brazing can be achieved.

  According to the invention described in [9] above, since the coating is applied after temporary assembly of the laminate, the amount of adhesion can be easily adjusted.

  According to the invention described in [10] above, the wettability reducing material can be attached to the entire circumference by pressing without provision of the wettability reducing material to the entire circumference before temporary assembly.

It is sectional drawing of the laminated body which temporarily assembled the electronic element mounting substrate and the heat sink. It is the elements on larger scale of Drawing 1, and is a sectional view showing the grant position of a wettability reducing material. It is a perspective view which shows the state which made the wettability reducing material adhere to the member before temporary assembly of a laminated body. It is sectional drawing of the laminated body temporarily assembled using the member of FIG. 3A. It is sectional drawing which shows the state which pressed the laminated body of FIG. 3B in the lamination direction. 3A to 3C are perspective views showing the application position and spreading area of the wettability reducing material in the wettability reducing material application method of FIGS. It is sectional drawing of the laminated body incorporating another heat sink. It is a perspective view of the punching metal used as a thermal stress relaxation material. It is sectional drawing of the laminated body incorporating the punching metal of FIG.

[Basic structure of laminate]
FIG. 1 shows an embodiment of a temporarily assembled laminate in the method for manufacturing a substrate electronic element mounting substrate according to the present invention.

  In the temporarily assembled laminated body (10), one surface of the ceramic substrate (11) is a surface to be an electronic element mounting surface, and the circuit layer (13) is overlaid through the brazing material (12). The other surface of the ceramic substrate (11) is a surface serving as a heat dissipation path, and a heat sink (15) is laminated via a thermal stress relaxation material (14), and the ceramic substrate (11) and the thermal stress relaxation material (14 ), Brazing materials (16) and (17) are arranged between the thermal stress relaxation material (14) and the heat sink (15), respectively, and the layers are stacked in the order shown in FIG.

  The present invention prevents elements derived from the heat sink (15) from entering the bonding interface between the ceramic substrate (11) and the thermal stress relaxation material (14) when the laminate (10) is brazed together. For the purpose.

[Details of each layer constituting the laminate]
The material of each layer constituting the laminate (10) is as follows.

  As the metal constituting the circuit layer (13), a metal having high conductivity and brazing to the ceramic substrate (11) is used, and high purity aluminum can be particularly recommended.

  Examples of the ceramic constituting the ceramic substrate (11) include aluminum nitride, aluminum oxide, silicon nitride, and zirconium oxide. These ceramics are recommended not only because of their excellent electrical insulation, but also because they have good thermal conductivity and excellent heat dissipation.

  Since the thermal stress relieving material (14) is a layer for relieving thermal stress generated at the bonding interface between the ceramic substrate (11) having a high rigidity and the heat sink (15), it is preferable to use soft aluminum. High purity aluminum is particularly preferable.

  As the aluminum constituting the heat sink (15), it is preferable to use a material excellent in strength maintenance, formability, and corrosion resistance, and Al—containing 0.5 to 1.5% by mass of Mn as having these characteristics Mn-based alloys and Al-Fe-based alloys containing 0.3 to 0.6 mass% Fe can be recommended. Also, since Mn and Fe are elements that, when mixed in the brazing material (16), form an intermetallic compound and lower the brazing property, this element prevents the element derived from the heat sink from entering the brazing material (16). The significance of applying the invention is great.

  As the brazing material (12), (16) and (17), a brazing material such as an Al—Si based alloy or an Al—Si—Mg based alloy is used. The brazing material (12), (16), and (17) may be placed between the layers as a brazing material foil, or integrated with the aluminum that constitutes the circuit layer (13), thermal stress relaxation material (14), and heat sink (15) It can also be used as a brazing sheet.

[Adhesion position of wettability reducing material]
In the laminate (10), as shown in FIG. 2, a wettability reducing material that reduces the wettability of the brazing material around the joint (18) between the ceramic substrate (11) and the thermal stress relaxation material (14). Grant (20). When brazing heat is applied with the wettability reducing material (20) applied, the wettability of the molten brazing material (16) decreases around the joint (18) and the brazing material (16) is repelled. Together with the brazing material (16) in which the elements from the outside are melted, they cannot enter the inside from the peripheral end (18a) of the joint (18). The element from the outside mentioned here is an element separated from the aluminum alloy constituting the heat sink (15) by brazing heat, and corresponds to Mn, Fe, or the like. These elements are elements that lower the brazeability when mixed in the brazing material (16). The brazing material (16) is attached to the joint (18) between the ceramic substrate (11) and the thermal stress relaxation material (14). Good brazing can be achieved by preventing intrusion. The ceramic substrate (11) and the thermal stress relieving material (14) are brazed well, so that heat and cooling are repeated in the usage environment of the substrate electronic device mounting substrate, and a very large thermal stress is received. Even in this case, peeling of the bonding interface is suppressed, and the durability of the bonding interface in the cooling and heating cycle is improved.

  The wettability reducing material (20) is preferably attached so as to cover at least the peripheral end (18a) and the portion adjacent to the peripheral end (18a) of the joint (18). In addition, since the element to prevent intrusion originates from the heat sink (15), the thermal stress relaxation material (14) that provides the shortest path from the heat sink (15) to the peripheral edge (18a) of the joint (18) It is preferable to apply to the outer peripheral surface (14a) of the ceramic substrate, and it is also preferable to apply to the portion of the ceramic substrate (11) adjacent to the peripheral end portion (18a) of the joint (18). In the illustrated laminate (10), the thermal stress relaxation material (14) has a smaller dimension than the ceramic substrate (11), and the outer peripheral surface (14a) of the thermal stress relaxation material (14) and the other of the ceramic substrate (11). Since the corner is formed by the surface (11a) (surface on the heat sink side), the outer peripheral surface (14a) of the thermal stress relaxation material (14) including the corner and the other surface of the ceramic substrate (11) It is preferable to add a wettability reducing material (20) to (11a). The wettability reducing material (20) needs to be applied without interruption in the circumferential direction around the joint (18), but it is not necessarily the outer peripheral surface (14a) of the thermal stress relaxation material (14) and the ceramic substrate (11 ) On the other side (11a). This is because, when the wettability reducing material (20) covers the peripheral end portion (18a) of the joint portion (18) and is applied to a portion adjacent to the peripheral end portion (18a), entry of elements can be prevented. FIG. 2 shows that the outer peripheral surface (14a) of the thermal stress relaxation material (14) is provided with a wettability reducing material (20) over the entire surface, and the other surface (11a) of the ceramic substrate (11) is joined with a joint ( 18 shows an example in which a wettability reducing material (20) is applied only to a portion adjacent to 18).

[Types of wettability reducing materials]
Examples of the wettability reducing material include boron nitride, carbon, resin, and adhesive. In the present invention, “the state in which the brazing material is poorly wet” and “the repelling of the brazing material” are cases where the contact angle with the brazing material is 90 ° or more. All of the above-described wettability reducing materials satisfy this condition.

  Both boron nitride and carbon have the property of repelling brazing material, and either one or both can be used in combination. As a method for applying these wettability reducing materials, it is possible to recommend a method in which a powder wettability reducing material is dispersed in an organic dispersion medium, or a method in which a binder is added to increase the viscosity. According to this application method, application to a predetermined position is easy, and adjustment of the amount of adhesion is easy. Examples of the organic dispersion medium include polyethylene glycol, methyl ethyl ketone, toluene, ethyl acetate, and thinner. As the organic dispersion medium, either a water-soluble organic dispersion medium or a water-insoluble organic dispersion medium can be used, but a non-aqueous medium that hardly evaporates during brazing is preferable. Further, a resin or wax may be added to the dispersion as a binder. When the binder is added, the viscosity of the liquid increases, so that the liquid does not easily drip at the time of application, and a required amount of the wettability reducing material can be easily attached. The binder is preferably an acrylic resin and preferably has a molecular weight of 10,000 to 1,500,000.

The amount of boron nitride and carbon applied is preferably in the range of 0.1 to 20 g / m ² . If it is less than 0.1 g / m ² , the effect of worsening the wettability of the brazing material is small, and mass application exceeding 20 g / m ² is uneconomical. Particularly preferable amounts of boron nitride and carbon are 1 to 15 g / m ² , respectively.

  The resin decomposes by heating during brazing to generate carbon, and the generated carbon functions as a wettability reducing material. Since the wettability reducing material needs to be present around the joint in a high temperature range close to the brazing temperature, it is necessary that carbon, which is a thermal decomposition product, remains at the position where the resin is adhered as a resin. It is. Specifically, it is possible to use a resin that remains as carbon at a position where it adheres at 560 ° C., which is close to the brazing temperature.

  The adhesive is also thermally decomposed by heating at the time of brazing to generate carbon and remains as carbon at the adhesion position at 560 ° C., so that it can be used as a wettability reducing material. Examples of adhesives that generate carbon include epoxy resins, phenol resins, and acrylic resins.

The resin and adhesive described above are added to a required position of the temporarily assembled laminate by adjusting the viscosity as appropriate by adding a solvent as necessary. The adhesion amounts of the resin and the adhesive are each preferably in the range of 0.5 to 50 g / m ² . If it is less than 0.5 g / m ² , the effect of deteriorating the wettability of the brazing material is small, and mass application exceeding 50 g / m ² is uneconomical. Particularly preferable application amounts of the resin and the adhesive are 1 to 15 g / m ² , respectively.

[Method of applying wettability reducing material]
The wettability reducing material only needs to adhere to the periphery of the joint at the time of brazing, so the application method is not limited, and the wettability reducing material may be applied either before or after temporarily assembling the laminate.

  When applying to a temporarily assembled laminated body, the wettability reducing material prepared in liquid or viscous liquid is applied to a required position. Since it is applied after temporary assembly, the amount of adhesion can be easily adjusted. If the shape of the laminate (10) of FIG. 2 is applied, it is applied around the corner of the bottom surface (11a) of the ceramic substrate (11) and the outer peripheral surface (14a) of the thermal stress relaxation material (14). , The peripheral end portion (18a) of the joint portion (18), and the portion adjacent to the peripheral end portion (18a) of the joint portion (18) of both surfaces (11a) (14a).

  As a method for temporarily assembling the laminate after applying the wettability reducing material, the following methods shown in FIGS. 3A to 3C can be recommended.

(1) FIG. 3A
A wettability reducing material (20) prepared in a liquid or viscous liquid is applied to one or both opposing surfaces (14b) (11a) of the ceramic substrate (11) and the thermal stress relaxation material (14). The application position is the edge in the region where both overlap. The broken line on the surface of the illustrated ceramic substrate (11) indicates a region where the thermal stress relaxation material (14) overlaps. Further, there is no need to spread the wettability reducing material (20) uniformly, and there is no need to continue in the circumferential direction. For example, what is necessary is just to give to dot shape like the example of illustration.

(2) FIG. 3B
The ceramic substrate (11) and the thermal stress relaxation material (14) are stacked together with other members to temporarily assemble the laminate (10).

(3) FIG. 3C
The temporarily assembled laminated body (10) is pressed in the laminating direction. By this pressing, the wettability reducing material (20) is expanded and connected in the circumferential direction, and is pushed outward from the laminated interface to be discharged to the outside. The wettability-decreasing material (20) extruded to the outside is both the surface (11a) (14a) adjacent to the peripheral end (18a) of the joint (18) and the peripheral end (18a) of the joint (18). ). FIG. 4 is a drawing showing the upper surface (surface facing the ceramic substrate) (14b) of the thermal stress relieving material (14), and shows the wettability reducing material (20) before pressing, which is attached in the form of dots, as a solid line, A region widened by the pressing is indicated by a broken line. The wettability reducing material (20) scattered in the circumferential direction is connected by pressing, and the wettability reducing material (20) reaches the entire circumference. Then, the wettability reducing material (20) is discharged to the outside from the bonding interface over the entire circumference and adheres to the periphery of the bonding portion (18). Similarly, also on the lower surface (11a) of the ceramic substrate (11), the wettability reducing material spreads by pressing and reaches the entire circumference, and is discharged outside from the bonding interface and adheres to the periphery of the bonding portion (18). Even if the laminate (10) is pressed, the wettability-reducing material remains slightly at the joint interface, but the outer edge is close to the peripheral edge and the residual amount is very small. Is not reached.

  According to the said method, even if it does not provide a wettability reducing material to a perimeter before temporary assembly, it can be made to adhere to a perimeter by pressing. However, the application position of the wettability reducing material before temporary assembly in the circumferential direction is arbitrary, and the case where it is applied to the entire circumference is also included in the present invention.

  If the wettability reducing material is a viscous dispersion or adhesive with a binder added, the wettability reducing material discharged to the outside is the ceramic substrate (11), brazing material (16), thermal stress relaxation material ( Since 14) is temporarily fixed, the handleability of the laminate (10) can be improved. Further, since the above three layers are temporarily fixed by the wettability reducing material, the laminated body can be completed by temporarily assembling the other members and the brazing material after temporarily fixing the three layers. Since such a temporary fixing effect is obtained, this application method is suitable for an adhesive or a viscous dispersion. In addition, a wettability reducing material may be additionally provided after temporary assembly.

[Brazing conditions]
The brazing conditions for the temporarily assembled laminate are not particularly limited, and examples include vacuum brazing and brazing in an inert gas atmosphere.

[Other Embodiments of Laminate]
In the present invention, the shape of each member is not limited to that described above.

  If the heat sink has a flat outer surface on the ceramic substrate side, it can be brazed to a large area with the ceramic substrate to obtain high heat dissipation performance, so any external shape or internal shape other than the surface on the ceramic substrate side can be used. Other shapes of the heat sink include a heat sink in which fins are brazed to the other surface of the flat plate, a heat sink in which fins are erected on the other surface of the flat plate, a tube heat sink having one or more hollow portions, and a fin in the hollow portion For example, a tube-type heat sink provided with the. In the case where the heat sink is completed by assembling and brazing a plurality of members, the temporarily assembled heat sink can be incorporated into the laminated body, and these can be simultaneously brazed together. For example, the heat sink (31) incorporated in the laminated body (30) shown in FIG. 5 forms a hollow part (33) by combining the upper and lower plate-like members (32a) and (32b), and the hollow part ( 33) A wavy fin (34) is arranged in the inside. The heat sink (31) temporarily assembled with these members is temporarily assembled together with the circuit layer (13), ceramic substrate (11), thermal stress relieving material (14), brazing material (12) (16) (17), and And brazed.

  Further, as shown in FIG. 6, a punching metal (41) having a through hole (42) for absorbing thermal stress may be used as the thermal stress relaxation material. As shown in FIG. 7, in the laminate (40) using such a punching metal (41), the element detached from the heat sink (15) may be mixed into the brazing material (16) through the through hole (42). There is. For this reason, it is preferable to apply a brazing material wetting prevention material to the peripheral surface (42a) of the through hole (42) of the punching metal (41) before the temporary assembly of the laminate (40). In the present invention, the influence of the thermal stress due to the thermal cycle is greatest at the outer peripheral end (19a) of the joint (19), and near the center (19a) is less affected than the outer peripheral end and the occurrence of peeling is small. Even when the punching metal (41) is used as the thermal stress relaxation material, it is not essential to apply the brazing material wettability reducing material to the peripheral surface (42a) of the through hole (42). In the laminated body (40), as shown in FIG. 7, the brazing material wetting prevention material (20) is applied around the outer peripheral end portion (19a) of the joint portion (19) of the ceramic substrate (11) and the punching metal (41). The case where the brazing material wetting prevention material (20) is not applied to the peripheral surface (42a) of the through hole (42) is also included in the technical scope of the present invention.

  A brazing test was performed in which the laminated body having the structure shown in FIG. 1 was temporarily assembled and brazed together. The member used in each example and the brazing condition of the laminated body are common, and only the wettability reducing material and the application method thereof are different.

  The ceramic substrate (11) is a flat plate made of aluminum nitride and having a size of 30 mm × 30 mm × thickness 0.6 mm. The circuit layer (13) is a 0.6 mm thick plate made of 99.99% or more high-purity aluminum. The thermal stress relaxation material (14) is made of high-purity aluminum of 99.99% or more, and is a flat plate of 28 mm × 28 mm × thickness 1.6 mm. The heat sink (15) is a 5 mm thick flat plate made of an Al-1 mass% Mn alloy. The brazing filler metals (12), (16), and (17) are 30 μm thick foils made of an Al-10 mass% Si-1 mass% Mg alloy.

(Examples 1 and 3)
A ceramic substrate (11) and a thermal stress relieving material (14) of a laminate (10) prepared by preparing a dispersion having a wettability reducing material concentration of 20% with a wettability reducing material and an organic dispersion medium shown in Table 1. The wettability-reducing material was applied to the inner corner and the outer peripheral surface (14a) of the thermal stress relaxation material (14) so that the adhesion amount of the wettability reducing material was 10 g / m ² . By this application, as shown in FIG. 2, the wettability reducing material (20) is applied to the peripheral end (18a) of the joint (18), the entire outer peripheral surface (14a) of the thermal stress relaxation material (14), and It adhered to a part of the other surface (11a) of the ceramic substrate (11) adjacent to the peripheral end (18a).

(Examples 2 and 4)
The corners of the ceramic substrate (11) and thermal stress relaxation material (14) of the laminated body (10) prepared by mixing the wettability reducing material, organic dispersion medium, and binder shown in Table 1 in a 1: 1: 1 ratio. The wettability reducing material (20) was applied to the outer peripheral surface (14a) of the part and the thermal stress relieving material (14) so that the adhesion amount of the wettability reducing material (20) was 10 g / m ² . The attachment position of the wettability reducing material (20) is the same as in Examples 1 and 3.

(Comparative example)
No wettability reducing material was applied.

(Examples 5-7)
The amount of adhesion of the wettability reducing material to the corner of the ceramic substrate (11) and the thermal stress relaxation material (14) of the laminate (10) temporarily assembled with the wettability reducing material (adhesive) shown in Table 1 is 10 g. / M ² to apply. By this application, the wettability reducing material (20) becomes part of the outer peripheral surface (14a) of the thermal stress relaxation material (14) adjacent to the peripheral end (18a) of the joint (18) and the peripheral end (18a). Then, it adhered to a part of the other surface (11a) of the ceramic substrate (11) adjacent to the peripheral end portion (18a).

(Example 8)
As shown in FIGS. 3A to 3C, the wettability reducing materials (adhesives) shown in Table 2 are placed on the opposing surfaces (11a) and (14b) of the ceramic substrate (11) and the thermal stress relaxation material (14) before temporary assembly. (20) is attached in the form of dots, stacked with other members to temporarily assemble the laminate (10), press the temporarily assembled laminate (10) in the stacking direction, and expand the wettability reducing material (20) They were connected in the circumferential direction and discharged from the laminated interface to the outside. As a result, the wettability reducing material (20) becomes a part of the outer peripheral surface (14a) of the thermal stress relaxation material (14) adjacent to the peripheral end (18a) of the joint (18) and the peripheral end (18a). Then, it adhered to a part of the other surface (11a) of the ceramic substrate (11) adjacent to the peripheral end portion (18a). Moreover, the adhesion amount of the wettability reducing material (20) was 10 g / m ² .

The temporarily assembled laminate (10) of each example was vacuum brazed at 600 ° C. for 20 minutes in a vacuum of 7 × 10 ⁻⁴ Pa.

  Each brazed product was subjected to a thermal test in which 2000 cycles of −40 ° C. and 125 ° C. were repeated to check for cracks in the ceramic substrate (11), and the ceramic substrate (11) and thermal stress relieving material (14 ) And the peeled area at the joint part was measured and evaluated according to the following criteria. The peeling area ratio is the ratio of the area of the part where peeling occurs to the total area of the joint. The evaluation results are shown in Table 1.

○: The ceramic substrate is not cracked and the peeled area ratio is less than 3%. Δ: The ceramic substrate is not cracked and the peeled area ratio is 3% or more and less than 5%. ×: The ceramic substrate is cracked. Or with a peeled area ratio of 5% or more

  From Table 1, the brazed product manufactured by the method of the present invention has the ceramic substrate and the thermal stress relaxation material brazed well, and the ceramic substrate is not cracked even in the thermal cycle, and the peeling at the bonding interface is suppressed. It was done.

  The present invention is suitable for manufacturing an electronic element mounting substrate in which a ceramic substrate and an aluminum heat sink are brazed simultaneously.

10, 30, 40 ... Laminated body
11 ... Ceramic substrate
11a… The other side
12, 16, 17 ... brazing material
13 ... circuit layer (aluminum circuit layer)
14 ... Thermal stress relaxation material (aluminum layer)
14a, 41a ... outer peripheral surface
15, 31 ... heat sink
18, 19 ... Junction
18a, 19a ... peripheral edge
20 ... Wetability reducing material
41 ... Punching metal (thermal stress relaxation material)
42 ... through hole

Claims (10)

A circuit layer made of metal is placed on one side of the ceramic substrate via a brazing material, and a thermal stress relaxation material made of aluminum and a heat sink made of aluminum are placed on the other side with a brazing material. Is a method of manufacturing a substrate for mounting an electronic device in which a laminated body is temporarily assembled and brazed together at the same time,
Electronic device mounting characterized in that brazing is performed in a state where a wettability reducing material that lowers the wettability of the brazing material is adhered around the joint between the ceramic substrate and the thermal stress relaxation material in the temporarily assembled laminate Manufacturing method for industrial use.   In the laminate in which the corner portion is formed by the outer peripheral surface of the thermal stress relaxation material and the other surface of the ceramic substrate, the outer peripheral surface of the thermal stress relaxation material and the other surface of the ceramic substrate including the corner portion. The manufacturing method of the board | substrate for electronic element mounting of Claim 1 which brazes in the state which made the wettability reducing material adhere.   The said thermal stress relaxation material is a punching metal which has a through-hole, and brazes in the state which made the wettability reducing material adhere to the surrounding surface of the said through-hole in the temporarily assembled laminated body. A method for manufacturing an electronic device mounting board.   The method for manufacturing a substrate for mounting an electronic element according to any one of claims 1 to 3, wherein the wettability reducing material is at least one of boron nitride and carbon.   The manufacturing method of the board | substrate for electronic element mounting of Claim 4 which adheres a wettability reducing material by apply | coating the dispersion liquid which disperse | distributed the said wettability reducing material to the organic dispersion medium.   The manufacturing method of the board | substrate for electronic element mounting of Claim 5 which adds a binder to the said dispersion liquid.   The method of manufacturing a substrate for mounting an electronic device according to any one of claims 1 to 3, wherein the wettability reducing material is a resin in which carbon, which is a decomposition product by heating, remains at an adhesion position at 560 ° C.   The method for manufacturing a substrate for mounting an electronic element according to claim 7, wherein the resin is an adhesive made of at least one of an epoxy resin, a phenol resin, and an acrylic resin.   The manufacturing method of the board | substrate for electronic element mounting in any one of Claims 1-8 which provides a wettability reducing material after temporarily assembling a laminated body.   A wettability reducing material is applied to the edge of one or both of the ceramic substrate and the thermal stress relaxation material before temporary assembly, and the laminate is temporarily assembled with other members, and the temporarily assembled laminate is obtained. The method for manufacturing a substrate for mounting an electronic element according to any one of claims 1 to 8, wherein the wettability reducing material is pressed out in a laminating direction to be discharged outside from the laminating interface and adhered to the periphery of the joint.

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