JP6952552B2 - Connection materials and thermoelectric conversion modules and electronics - Google Patents

Description

The present invention relates to electrically connected connecting materials and thermoelectric conversion modules and electronic devices.

For example, Japanese Patent Application Laid-Open No. 2008-126272 (Patent Document 1) discloses a technique for improving connection reliability with respect to thermal stress applied to a connection portion of an element, and Patent Document 1 describes an Al-based alloy. It is described that a connecting material having a Zn-based alloy layer provided on the outermost surface of the layer is used.

Japanese Unexamined Patent Publication No. 2008-126272

Patent Document 1 describes that a connecting material formed by laminating a Zn-based alloy layer, an Al-based alloy layer, and a Zn-based alloy layer is used, and a Zn-Al alloy bonding layer is used during the connection process. By forming the soft Al layer and the soft Al layer, the soft Al layer functions as a stress buffering material.

However, since Zn is an element that is easily dissolved in Al, the soft Al layer is maintained by the solid solution of Zn in Al at the connection portion after the connection material is connected or during the high temperature operation of the electronic device. You will not be able to. As a result, it becomes difficult to obtain the stress buffering function by the Al layer of the connecting portion, and there is a concern that the connection reliability of the connecting portion is lowered.

An object of the present invention is to provide a technique capable of improving the connection reliability of a connection portion using a connection material in a high temperature environment.

The aforementioned objects and novel features of the present invention will become apparent from the description and accompanying drawings herein.

A brief overview of typical embodiments disclosed in the present application is as follows.

The connecting material in one embodiment includes an Al layer, a Ni layer, and a first alloy layer composed of Al and Ni. Further, the first alloy layer is arranged between the Al layer and the Ni layer, and the Al content in the Al layer is 99 at% or more.

The thermoelectric conversion module in one embodiment is a first alloy composed of a plurality of thermoelectric elements, a plurality of electrodes electrically connected to the plurality of thermoelectric elements, an Al layer, a Ni layer, and Al and Ni. With a connecting material having a layer. Further, the first alloy layer is arranged between the Al layer and the Ni layer, and the Al content in the Al layer is 99 at% or more. Further, the plurality of thermoelectric elements and the plurality of electrodes are each connected via the connection material.

The electronic device in one embodiment includes a semiconductor element, a substrate on which the semiconductor element is mounted, a conductor portion formed on the surface of the substrate and to which the semiconductor element is connected, an Al layer, a Ni layer, and Al. It has a connecting material having a first alloy layer composed of and Ni. Further, the first alloy layer is arranged between the Al layer and the Ni layer, and the Al content in the Al layer is 99 at% or more. Further, the semiconductor element and the conductor portion are connected via the connecting material.

Among the inventions disclosed in the present application, the effects obtained by representative ones will be briefly described as follows.

In the connection portion using the connection material, the thermal stress can be buffered and the connection reliability in a high temperature environment can be improved.

It is a partial cross-sectional view which shows the structure of the main part of the thermoelectric conversion module of this invention. It is a binary phase diagram of Al and Ni related to the connection material of this invention. It is a partial cross-sectional view which shows the structure of the main part of the thermoelectric conversion module of 1st Embodiment in Example 1 of this invention. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is an evaluation result figure which shows the result of the element cracking evaluation with respect to the thickness of the Al layer of the connection material of this invention. It is an evaluation result figure which shows the result of the connection possibility evaluation for each connection condition of the connection material of this invention. It is a partial cross-sectional view which shows the structure of the main part of the thermoelectric conversion module of the 2nd form in Example 1 of this invention. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a partial cross-sectional view which shows a part of the manufacturing method of the main part of the thermoelectric conversion module of FIG. It is a perspective view which shows the whole structure of the thermoelectric conversion module of Example 1 of this invention. It is a partial cross-sectional view which shows the structure of the main part of the thermoelectric conversion module of 1st embodiment of Example 2 of this invention. It is a partial cross-sectional view which shows the structure of the main part of the thermoelectric conversion module of 2nd Embodiment of this invention. It is a partial cross-sectional view which shows the structure of the main part of the thermoelectric conversion module of the 3rd embodiment of Example 2 of this invention. It is a partial cross-sectional view which shows the structure of the main part of the thermoelectric conversion module of the 4th embodiment of Example 2 of this invention. It is sectional drawing which shows the structure of the main part of the power module which is an example of the electronic device of Example 3 of this invention. It is an evaluation result figure which shows the result of the connection possibility evaluation with respect to each connection condition of the connection material in the power module shown in FIG.

In the present embodiment, in a connecting material for electrical and mechanical connection, the connecting material is provided with an Al (aluminum) layer that is soft and has high purity, and the Al layer provides stress such as thermal stress. It describes the buffering technique. At that time, in the present embodiment, the stress is buffered by the soft Al layer by suppressing the reaction with Al as much as possible while maintaining the connectivity with Al.

FIG. 1 is a partial cross-sectional view showing the structure of a main part of the thermoelectric conversion module of the present invention, and shows the connection portions of the P-type thermoelectric element and the N-type thermoelectric element of the thermoelectric conversion module.

In the connection structure shown in FIG. 1, a P-type thermoelectric element 421 which is a P-type thermoelectric element and an N-type thermoelectric element 422 which is an N-type thermoelectric element are connected to a stress buffering material 21 which is a connection material of the present embodiment. Is joined via the electrode 11.

Alternatively, the structure may be such that the P-type thermoelectric element 421 and the N-type thermoelectric element 422 are electrically connected by using the stress cushioning material 21 as an electrode (for example, the connection structure of FIG. 18 described later).

The stress cushioning material (connecting material) 21 of the present embodiment has a structure in which a plurality of metal layers are laminated. Specifically, the stress buffering material 21 is composed of an Al layer 211, a Ni (nickel) layer 213, and an Al—Ni alloy layer (first alloy layer) 212 which is an alloy layer of Al and Ni, and The Al content in the Al layer 211 is 99 at% or more.

Further, the stress cushioning material 21 has an Al—Ni alloy layer 212 at the interface between the Al layer 211 and the Ni layer 213. In other words, the Al—Ni alloy layer 212 is arranged between the Al layer 211 and the Ni layer 213. As described above, in the stress cushioning material 21, the Al—Ni alloy layer 212 is formed at the interface between the Al layer 211 and the Ni layer 213, so that Al and Ni can be firmly connected.

In the connection structure shown in FIG. 1, the stress cushioning material 21 has an Al layer 211 arranged as a central layer thereof, and an Al—Ni alloy layer 212 is provided above and below the Al layer 211 so as to sandwich the Al layer 211. The Ni layer 213 is further arranged on the surface layer of the Al—Ni alloy layer 212. Then, one Ni layer 213 of the stress cushioning material 21 is connected to the electrode 11, and the other Ni layer 213 of the stress cushioning material 21 is connected to the P-type thermoelectric element 421 or the N-type thermoelectric element 422 via the metallize 411, respectively. It is connected to either. The metallize 411 is made of, for example, Ni.

Next, FIG. 2 is a binary phase diagram of Al and Ni related to the connecting material of the present invention. As shown in FIG. 2, in the case of Al and Ni, Ni hardly dissolves in Al (α-Al portion in the phase diagram of FIG. 2). That is, in the Al layer 211 and the Ni layer 213 as in the present embodiment, solid solution to the pure Al portion, which is a problem in the clad structure in which Zn (zinc), Al, and Zn are laminated, occurs. It's hard to do. As a result, the stress-cushioning material 21 of the present embodiment can maintain a soft pure Al portion (Al layer 211) even after connection or during high-temperature operation of the electronic device, and can exhibit a stress-cushioning function. It will be possible.

Further, since Ni hardly dissolves in Al, it is possible to suppress the diffusion of members into the Al layer 211. That is, in the stress cushioning material 21, the Al layer 211 can be left as a soft layer with high purity of the Al layer, so that the stress cushioning function can be exhibited. Specifically, by setting the purity of Al in the Al layer 211 to 99 at% or more, it is possible to obtain the effect of stress buffering of the Al layer 211.

For example, in the case of Al alloys, in the case of 2000 series to 7000 series (2000 series to 7000 series) Al alloys, the strength of Al increases with the added elements, so that it is difficult to obtain a stress buffering effect. Therefore, if it is 1000 series (1000 series) Al, the purity of Al is high, so that it is possible to form a soft Al layer. That is, when the purity of Al in the Al layer is 99 at% or more, the stress buffering effect of the present embodiment can be exhibited.

Further, the thickness of the Al layer 211 is preferably in the range of 100 to 500 μm. If the Al layer 211 is too thin, the area of the soft stress buffer layer is small, so that the thermal stress cannot be sufficiently buffered. On the other hand, when the thickness of the Al layer 211 is large, the influence of the coefficient of thermal expansion of Al becomes large, which promotes the thermal stress load on the P-type thermoelectric element 421 and the N-type thermoelectric element 422. Therefore, by setting the thickness of the Al layer 211 to 100 to 500 μm, the thermal stress in the Al layer 211 can be sufficiently buffered, and the thermal stress load on the P-type thermoelectric element 421 and the N-type thermoelectric element 422 can be sufficiently buffered. Can be reduced.

The thickness of the Ni layer 213 is preferably in the range of 1 to 100 μm. If the Ni layer 213 is too thin, the formation of the Al—Ni alloy layer 212 becomes insufficient, and a stable bonding interface cannot be formed. On the other hand, if the Ni layer 213 is too thick, the rigidity of the layer becomes high, which hinders the stress buffering function of the Al layer 211. That is, by setting the thickness of the Ni layer 213 to 1 to 100 μm, the Al—Ni alloy layer 212 is sufficiently formed, and a stable bonding interface can be obtained. Further, the rigidity of the Ni layer 213 does not become too high, and the stress buffering function of the Al layer 211 can be exhibited.

Further, in the stress cushioning material 21, it is possible to add the outermost layer in accordance with the P-type thermoelectric element 421, the N-type thermoelectric element 422, and the electrode 11 which are the connected materials. For example, as shown in FIG. 3 described later, the Al layer 211 is arranged as a layer located at the center in the stacking direction of the stress cushioning material 21, and the Al—Ni alloy layer 212 is arranged so as to sandwich the Al layer 211. doing. Further, the Ni layer 213 is arranged on the surface layer of the Al—Ni alloy layer 212, and the Cu layer 214 is arranged on the surface layer of the Ni layer 213 on the side connected to the thermoelectric element. The Cu layer 214 is connected to the thermoelectric element via a metallize 411 made of Ni or the like.

As a result, the stress cushioning material 21 can secure connectivity with the metallized 411 arranged on the surface layer of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422. The metallized 411 and the Cu layer 214 on the outermost surface of the stress cushioning material 21 can be connected by a solid phase diffusion connection.

As described above, the layers formed on the outermost surfaces of the front and back surfaces of the stress cushioning material 21 do not necessarily have to be the same. For example, when Ni is formed as metallize 411 on the surface of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422, and the electrode 11 is made of Cu, the layer structure does not have to be the same on both sides. Specifically, as shown in FIG. 3, which will be described later, the stress cushioning material that connects the outermost surface of the stress cushioning material 21 connected to the electrode 11 side to the Ni layer 213, the P-type thermoelectric element 421, and the N-type thermoelectric element 422 side. The outermost surface of 21 is the Cu layer 214.

As a result, it is possible to achieve a highly reliable connection between the electrode 11 and the P-type thermoelectric element 421 and the N-type thermoelectric element 422 via the stress cushioning material 21 (see Example 1 described later). The Cu layer 214 and the Ni layer 213 are connected via a Cu—Ni alloy layer (second alloy layer) 215, which is an alloy layer composed of Cu and Ni. In other words, the Cu—Ni alloy layer 215 is connected to the Cu layer 214 and the Ni layer 213.

Next, each connection condition in the connection using the stress cushioning material 21 of the present embodiment will be described.

First, the connection temperature will be described. The connection temperature is preferably 350 to 500 ° C. If the connection temperature is too low, the thermal activity is insufficient and the connection cannot be achieved. On the other hand, when the connection temperature is too high, the soft Al layer 211 becomes even softer due to the temperature dependence, so that the deformation at the time of connection becomes large. If the deformation at the time of connection becomes too large, the P-type thermoelectric element 421, the N-type thermoelectric element 422, and the electrode 11 are each tilted, so that the contact property of the thermoelectric conversion module with the heat source is lowered.

Next, the connection time will be described. The connection time is preferably 5 to 60 minutes. If the connection time is short, the diffusion between atoms is insufficient as in the case where the connection temperature is low, leading to poor connection. On the other hand, if the connection time is long, a strong connection can be achieved, but if the connection time is too long, the productivity is lowered.

Next, the pressing force at the time of connection will be described. The pressing force is preferably 1 to 10 MPa. If the pressing force is too low, the contact between the members becomes insufficient, the diffusion between atoms does not proceed, and the connection cannot be achieved. On the other hand, if the pressing force is too high, the Al layer 211 and the electrode 11 are deformed, so that the contact property of the thermoelectric conversion module with the heat source is lowered.

As described above, when connected at the above-mentioned desirable connection temperature, connection time and pressing force, the soft Al layer 211 is appropriately deformed to achieve the connection between the metallized 411 and the electrode 11 via the stress cushioning material 21. It is possible to suppress the warp and dent of the electrode 11 due to pressurization. Specifically, the deformation of the electrode 11 due to warpage or dent can be suppressed within 30 μm.

The stress cushioning material 21 does not necessarily have to be formed on both surfaces of the connecting surfaces of the P-type thermoelectric element 421 and the N-type thermoelectric element 422. The thermoelectric conversion module is exposed to a high temperature on one side and a low temperature on the other side during operation. Therefore, the connection on the low temperature side can be made by using a low melting point connecting material such as solder. Further, in the present embodiment, the stress cushioning material 21 can be used as a substitute for the electrode 11.

Further, in the present embodiment, the thermoelectric conversion module is mentioned as an example of the electronic device, but the stress cushioning material 21 can also be used as a connecting material for elements in a power module or the like. The power module has a structure in which elements such as Si, SiC, and GaN are connected to an insulating substrate with metal wiring, and the insulating substrate is further connected to a metal base plate. In the power module, the thermal stress due to the heat generation of the element is applied to the element and the connecting portion during operation. Therefore, by using the stress cushioning material 21 of the present embodiment as the connecting material, the thermal stress is applied. It becomes possible to cushion and improve the reliability of the power module.

Hereinafter, embodiments of the present invention will be described as examples using figures. In each figure, the same components are designated by the same reference numerals.

(Example 1)
FIG. 3 is a partial cross-sectional view showing the structure of a main part of the thermoelectric conversion module of the first embodiment in the first embodiment of the present invention. In the connection structure shown in FIG. 3, the electrode 11 is made of Cu, and each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 is joined to the electrode 11 via the stress cushioning material 21. Then, in the stress cushioning material 21, the Al layer 211 is positioned at the center in the stacking direction, and the Al—Ni alloy layer 212, the Ni layer 213, and the Cu layer 214 are formed in this order from the Al layer 211 in the vertical direction. However, the Cu layer 214 is formed only on the connection side of the stress cushioning material 21 with the thermoelectric element.

The stress cushioning material 21 is formed by a clad method in which the surfaces of Al, Ni and Cu are rolled and connected while applying pressure. At that time, the thickness of the Al layer 211 was set to 50 to 700 μm, the thickness of the Ni layer 213 was set to 20 μm, and the thickness of the Cu layer 214 was set to 20 μm.

4 to 8 are partial cross-sectional views showing a part of a manufacturing method of a main part of the thermoelectric conversion module of FIG. 3, respectively.

First, as shown in FIG. 4, two electrodes 11 are prepared, then, as shown in FIG. 5, a stress cushioning material 21 is placed on each electrode 11, and then each stress cushioning material is placed. A metallize 411 made of Ni is formed on the 21. Then, as shown in FIG. 6, a P-type thermoelectric element 421 and an N-type thermoelectric element 422 having metallized 411 on the opposite side thereof are separately placed on the metallized 411. Further, as shown in FIG. 7, a stress cushioning material 21 is placed on each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 subjected to metallization 411, and then, as shown in FIG. 8, as shown in FIG. The electrode 11 is placed on each stress cushioning material 21. Although not shown, the electrode 11, the stress cushioning material 21, the P-type thermoelectric element 421, and the N-type thermoelectric element 422 can be arranged at desired positions by using an alignment jig. A thermoelectric conversion module is manufactured by pressurizing the electrodes 11 after the arrangement and further heating the entire member. In either case, the Ni layer 213 and the Cu layer 214 are connected via the Cu—Ni alloy layer 215.

Here, FIG. 9 is an evaluation result diagram showing the result of element cracking evaluation with respect to the thickness of the Al layer of the connecting material of the present invention. That is, FIG. 9 shows the influence of the thickness of the Al layer 211 on the stress cushioning material 21. Those having no Al thickness (0) were evaluated as a bimetal clad material having a Ni layer 213 thickness of 20 μm and a Cu layer 214 thickness of 20 μm as a comparative material. As shown in FIG. 9, when there is no Al thickness (in the case of 0), element cracking occurs after connection, but the Al thickness is in the range of 100 to 500 μm (Nos. 3, 4, 5, 6 in FIG. 9). ), The element cracking does not occur, and the stress buffering effect can be exhibited. On the other hand, if the thickness of the Al layer 211 exceeds 500 μm, cracks occur. Therefore, the appropriate thickness of the Al layer 211 for exerting the stress buffering function is 100 to 500 μm. Further, in any structure, the Cu layer 214 and the Ni layer 213 are connected via the Cu—Ni alloy layer 215, whereby the connection between the Cu layer 214 and the Ni layer 213 is strong. Has been achieved.

Next, FIG. 10 is an evaluation result diagram showing the result of the connectability evaluation for each connection condition of the connection material of the present invention. That is, FIG. 10 shows the possibility of connection and the degree of electrode deformation for each connection condition. For the connection in FIG. 10, a clad material having an Al thickness of 300 μm in FIG. 9 is used. As shown in FIG. 10, when the connection temperature was 300 ° C. (Nos. 1, 2, 3, and 4 in FIG. 10), the connection could not be achieved regardless of the connection time and the connection pressure (connection availability is ×). ..

Further, when the connection temperature is 350 ° C. or higher, the connection can be achieved as the connection time and the connection pressure increase (Nos. 7, 8, 10, 11, 12, 14 to 22 in FIG. 10). However, when the connection temperature and the connection pressure are high (for example, No. 20), although the connection can be achieved, the electrode deformation exceeding 30 μm has been confirmed after the connection.

Therefore, in the first embodiment, in the connection using the stress cushioning material 21, the thermoelectric conversion module with improved connection reliability by applying the connection condition in which the electrode deformation is small (30 μm or less) while achieving this connection. Can be realized. Further, it is possible to manufacture a thermoelectric conversion module having a structure that makes it easy to secure a temperature difference between the high temperature side and the low temperature side.

Next, FIG. 11 is a partial cross-sectional view showing the structure of a main part of the thermoelectric conversion module of the second embodiment according to the first embodiment of the present invention.

As described above, the stress cushioning material 21 does not necessarily have to be formed on both sides of the P-type thermoelectric element 421 and the N-type thermoelectric element 422. In the connection structure shown in FIG. 11, one surface of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 is connected to the electrode 11 via the stress buffering material 21, and the other surface is connected to the electrode 11 via the connecting material 22. You are connected. It is different from the connection structure of FIG. 3 in that only one surface of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 is connected to the electrode 11 via the stress cushioning material 21. For example, solder is used as the connecting material 22, and in the connection structure shown in FIG. 11, the other surfaces of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 are connected via the connecting material 22 such as solder. It is connected to the electrode 11.

Next, FIGS. 12 to 16 are partial cross-sectional views showing a part of a manufacturing method of a main part of the thermoelectric conversion module of FIG. 11, respectively.

Assembling the main parts of the thermoelectric conversion module shown in FIGS. 12 to 16 will be described. First, as shown in FIG. 12, two electrodes 11 are prepared, and then, as shown in FIG. 13, each electrode 11 is prepared. The stress cushioning material 21 is placed on the surface. After that, as shown in FIG. 14, a P-type thermoelectric element 421 and an N-type thermoelectric element 422 subjected to metallization 411 made of Ni are separately placed on the respective stress cushioning materials 21. Then, pressurization and heating are performed in this state. As a result, the respective electrodes 11, the P-type thermoelectric element 421, and the N-type thermoelectric element 422 are connected via the stress cushioning material 21, respectively.

Next, as shown in FIG. 15, the connecting material 22 is placed on each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 that have been subjected to metallization 411. Here, the connecting material 22 is, for example, solder. Next, as shown in FIG. 16, the electrodes 11 are placed on both connecting members 22, and then pressurized and heated. As a result, the P-type thermoelectric element 421, the N-type thermoelectric element 422, and the electrode 11 are connected to each other via the connecting material 22, and a thermoelectric conversion module can be manufactured.

As the connection conditions in the state shown in FIG. 14, the same results as in FIGS. 9 and 10 were obtained. Further, as the connection in the state of FIG. 16, the P-type thermoelectric element 421 and the N-type thermoelectric element 422 are cracked by connecting in a formic acid atmosphere with a connection temperature of 350 ° C., a connection time of 10 minutes, and a connection pressure of 0.01 MPa. Can be achieved without the occurrence of. Since the connecting material 22 such as solder has a lower connection temperature than the stress cushioning material 21, it can be connected by two pressurization and heating processes. In addition, by connecting with solder or a conductive metal paste, it is possible to absorb the height variation of each member, and it is possible to improve the assembleability of the thermoelectric conversion module.

Next, FIG. 17 is a perspective view showing the overall structure of the thermoelectric conversion module according to the first embodiment of the present invention. In the thermoelectric conversion module shown in FIG. 17, a stress cushioning material 21 is used at the connection portion of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 with the electrodes 11, but in FIG. 17, the stress cushioning material 21 is used. It has been omitted.

The thermoelectric conversion module shown in FIG. 17 has a plurality of thermoelectric elements and a plurality of electrodes 11 electrically connected to the plurality of thermoelectric elements. Then, the plurality of thermoelectric elements and the plurality of electrodes 11 are connected to each other via a stress cushioning material (connecting material) 21 as shown in FIG. The thermoelectric element is a P-type thermoelectric element 421 and an N-type thermoelectric element 422, and the P-type thermoelectric element 421 and the N-type thermoelectric element 422 are attached to any (at least one) of the plurality of electrodes 11. Each is electrically connected via a stress buffer 21.

Further, in the thermoelectric conversion module shown in FIG. 17, the electrode 11, the P-type thermoelectric element 421 and the N-type thermoelectric element 422 are each electrically formed in a series circuit.

As a result, when a temperature difference is applied to the front and back surfaces of the thermoelectric conversion module, electric power can be taken out from the lead wire 52 connected to the terminal 52a on the electrode 11 located at the end. Although the case where the electrode 11 is made of Cu has been described in the first embodiment, the same effect as that of the thermoelectric conversion module of the first embodiment can be obtained even when the insulating substrate with copper wiring is used as the electrode.

(Example 2)
FIG. 18 is a partial cross-sectional view showing the structure of a main part of the thermoelectric conversion module according to the first embodiment of the second embodiment of the present invention. In the connection structure of the second embodiment shown in FIG. 18, the P-type thermoelectric element 421 and N are subjected to metallization 411 so that the stress cushioning material 21 also serves as an electrode without using the electrode 11 as shown in FIG. The type thermoelectric element 422 is connected. As described above, the connection structure of the second embodiment is different from the first embodiment in that the stress cushioning material 21 is connected to the P-type thermoelectric element 421 and the N-type thermoelectric element 422 in a form that also serves as an electrode.

As a result, according to the connection structure of FIG. 18, since the electrode 11 does not need to be used, the number of parts can be reduced and the cost of the thermoelectric conversion module can be reduced.

Next, FIG. 19 is a partial cross-sectional view showing the structure of a main part of the thermoelectric conversion module of the second embodiment of the second embodiment of the present invention. In the connection structure shown in FIG. 19, a stress cushioning material 21 that also serves as an electrode is connected to one surface of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422, and the other surface is connected to the electrode 11 via the metallize 411. Is a connected structure. That is, the stress cushioning material 21 is not connected to the other surface, and the thermoelectric element is connected to the electrode 11 via the metallize 411.

As described above, in the connection structure shown in FIG. 19, the stress buffering material 21 also serving as an electrode is connected to only one surface of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422. Is different.

Next, FIG. 20 is a partial cross-sectional view showing the structure of a main part of the thermoelectric conversion module of the third embodiment of the second embodiment of the present invention. In the connection structure shown in FIG. 20, a stress cushioning material 21 that also serves as an electrode is connected to one surface of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 via a connecting material 22 such as solder, and the other. The surface of the surface has a structure in which the metallized 411 is connected to the electrode 11 via a connecting material 22. That is, one surface of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 is connected to the stress cushioning material 21 via the connecting material 22, and the other surface of each is an electrode via the connecting material 22. It is connected to 11.

Further, FIG. 21 is a partial cross-sectional view showing the structure of a main part of the thermoelectric conversion module according to the fourth embodiment of the second embodiment of the present invention. In the connection structure shown in FIG. 21, one surface of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422 is connected to the electrode 11 via a connecting material 22, and the other surface also serves as an electrode. It is connected only to the stress buffer 21 in the shape of a shape and the metallized 411.

As described above, in the connection structure shown in FIGS. 18 to 21, when the stress cushioning material 21 is used as an electrode on at least one surface of each of the P-type thermoelectric element 421 and the N-type thermoelectric element 422, the connection material is used. It is possible to perform solid-phase diffusion bonding without using 22. However, the connecting material 22 can also be used depending on the operating temperature range of the thermoelectric conversion module. In either case, a highly reliable thermoelectric conversion module can be realized by the stress buffering effect of the Al layer 211.

(Example 3)
FIG. 22 is a cross-sectional view showing the structure of a main part of a power module which is an example of the electronic device according to the third embodiment of the present invention, and FIG. It is an evaluation result figure which shows.

The structure of the power module of the third embodiment shown in FIG. 22 will be described. The power module shown in FIG. 22 is a metal wiring layer (conductor portion) formed on the surface of a semiconductor chip (semiconductor element) 51, a substrate 63 on which the semiconductor chip 51 is mounted, and the semiconductor chip 51, and to which the semiconductor chip 51 is connected. ) 61 and a stress buffering material (connecting material) 21. As shown in FIG. 1, the stress cushioning material 21 is, for example, a connecting material having an Al layer 211, a Ni layer 213, and an Al—Ni alloy layer 212 composed of Al and Ni. Then, the semiconductor chip 51 and the metal wiring layer 61 are electrically and mechanically connected via the stress cushioning material 21.

Further, the substrate 63 is composed of an insulating layer 62 and a metal wiring layer 61 formed on both the front and back surfaces of the insulating layer 62. Then, the substrate 63 to which the semiconductor chip 51 is connected is mounted on the metal base plate 81 via the bonding layer 71. Further, the electrodes of the semiconductor chip 51 and the metal wiring layer 61 of the substrate 63 are electrically connected by using the conductive wire 91.

The insulating layer 62 of the substrate 63 is made of, for example, ceramics, and the metal wiring layer 61 is made of, for example, Cu. The wire 91 is made of, for example, Al or Cu.

Further, Ni is applied as metallize 411 on the back surface of the semiconductor chip 51. Then, the Ni of the metallized 411 applied to the semiconductor chip 51 and the metal wiring layer 61 of the substrate 63 are connected by the stress cushioning material 21, thereby preventing the semiconductor chip 51 from cracking due to thermal stress. be able to.

Here, as shown in the evaluation result diagram of the connection availability evaluation in FIG. 23, No. 1 to 12 are the same as the results of Example 1, but in Example 3, chip cracking occurs due to thermal stress when the connection temperature exceeds 400 ° C. Therefore, it is possible to realize a power module with high connection reliability by connecting at a connection temperature of 350 to 400 ° C.

Although the invention made by the present inventor has been specifically described above based on the embodiment, the present invention is not limited to the above-described embodiment and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations.

Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. .. Further, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. It should be noted that each member and the relative size described in the drawings have been simplified and idealized in order to explain the present invention in an easy-to-understand manner, and have a more complicated shape in terms of mounting.

For example, in the third embodiment, the power module is taken as an example of the electronic device, and the structure of the main part of the power module has been described. However, the number of semiconductor chips 51 to be installed may be two or more. .. Further, although not shown, it is desirable that the semiconductor chip 51 is sealed with a sealing material such as a thermosetting resin.

11 Electrode 21 Stress cushioning material (connecting material)
22 Connection material 211 Al layer 212 Al—Ni alloy layer (first alloy layer)
213 Ni layer 214 Cu layer 215 Cu-Ni alloy layer (second alloy layer)
411 Metallize 421 P-type thermoelectric element (thermoelectric element)
422 N-type thermoelectric element (thermoelectric element)
51 Semiconductor chip (semiconductor element)
52 Lead wire 52a terminal 61 Metal wiring layer (conductor part)
62 Insulation layer 63 Substrate 71 Bonding layer 81 Base plate 91 Wire

Claims (11)

Al layer and
Ni layer and
A first alloy layer composed of Al and Ni,
Cu layer and
A second alloy layer laminated on the Cu layer and composed of Cu and Ni,
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The content of Al in the Al layer state, and are more than 99 at%,
The second alloy layer is a connecting material connected to the Ni layer. Al layer and
Ni layer and
A first alloy layer composed of Al and Ni,
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The content of Al in the Al layer state, and are more than 99 at%,
A connecting material having an Al layer having a thickness of 100 to 500 μm. Al layer and
Ni layer and
A first alloy layer composed of Al and Ni,
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The content of Al in the Al layer state, and are more than 99 at%,
A connecting material having a thickness of the Ni layer of 1 to 100 μm. With multiple thermoelectric elements
A plurality of electrodes electrically connected to the plurality of thermoelectric elements, respectively,
A connecting material having an Al layer, a Ni layer, a first alloy layer composed of Al and Ni, a Cu layer, and a second alloy layer laminated on the Cu layer and composed of Cu and Ni.
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The Al content in the Al layer is 99 at% or more, and is
The plurality of thermoelectric elements and the plurality of electrodes are connected via the connecting material, respectively .
The second alloy layer is a thermoelectric conversion module connected to the Ni layer. With multiple thermoelectric elements
A plurality of electrodes electrically connected to the plurality of thermoelectric elements, respectively,
A connecting material having an Al layer, a Ni layer, and a first alloy layer composed of Al and Ni.
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The Al content in the Al layer is 99 at% or more, and is
The plurality of thermoelectric elements and the plurality of electrodes are connected via the connecting material, respectively .
A thermoelectric conversion module having an Al layer having a thickness of 100 to 500 μm. With multiple thermoelectric elements
A plurality of electrodes electrically connected to the plurality of thermoelectric elements, respectively,
A connecting material having an Al layer, a Ni layer, and a first alloy layer composed of Al and Ni.
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The Al content in the Al layer is 99 at% or more, and is
The plurality of thermoelectric elements and the plurality of electrodes are connected via the connecting material, respectively .
The thermoelectric conversion module having a thickness of the Ni layer of 1 to 100 μm. The thermoelectric conversion module according to any one of claims 4 to 6.
Each of the plurality of thermoelectric elements includes a P-type thermoelectric element and an N-type thermoelectric element.
A thermoelectric conversion module in which the P-type thermoelectric element and the N-type thermoelectric element are electrically connected to at least one of the plurality of electrodes via the connection material. With semiconductor elements
The substrate on which the semiconductor element is mounted and
A conductor portion formed on the surface of the substrate and to which the semiconductor element is connected and
A connecting material having an Al layer, a Ni layer, a first alloy layer composed of Al and Ni, a Cu layer, and a second alloy layer laminated on the Cu layer and composed of Cu and Ni.
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The Al content in the Al layer is 99 at% or more, and is
The semiconductor element and the conductor portion are connected via the connecting material, and the semiconductor element and the conductor portion are connected via the connecting material .
The second alloy layer is an electronic device connected to the Ni layer. With semiconductor elements
The substrate on which the semiconductor element is mounted and
A conductor portion formed on the surface of the substrate and to which the semiconductor element is connected and
A connecting material having an Al layer, a Ni layer, and a first alloy layer composed of Al and Ni.
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The Al content in the Al layer is 99 at% or more, and is
The semiconductor element and the conductor portion are connected via the connecting material, and the semiconductor element and the conductor portion are connected via the connecting material .
An electronic device having an Al layer having a thickness of 100 to 500 μm. With semiconductor elements
The substrate on which the semiconductor element is mounted and
A conductor portion formed on the surface of the substrate and to which the semiconductor element is connected and
A connecting material having an Al layer, a Ni layer, and a first alloy layer composed of Al and Ni.
Have,
The first alloy layer is arranged between the Al layer and the Ni layer.
The Al content in the Al layer is 99 at% or more, and is
The semiconductor element and the conductor portion are connected via the connecting material, and the semiconductor element and the conductor portion are connected via the connecting material .
An electronic device having a thickness of the Ni layer of 1 to 100 μm. In the electronic device according to any one of claims 8 to 10.
An electronic device in which the insulating layer of the substrate is made of ceramics and mounted on a metal base plate.

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