JP5092168B2 - Peltier element thermoelectric conversion module, manufacturing method of Peltier element thermoelectric conversion module, and optical communication module - Google Patents

Description

  The present invention relates to a micro-sized Peltier element thermoelectric conversion module used for precise temperature control of a laser diode of an optical communication module, and more specifically, to lead-free the entire optical communication module and the laser diode optical axis. The present invention relates to a gold-tin bonded Peltier element thermoelectric conversion module having a bonding structure useful for preventing deviation.

  FIG. 28 is a conceptual diagram showing a general configuration of a thermo module (Peltier element thermoelectric conversion module) 80 used for various temperature control and the like.

  The thermo module 80 is joined between the ceramic substrates 11 and 12 so that a P-type thermoelectric semiconductor element 13a and an N-type thermoelectric semiconductor element 13b mainly composed of bismuth and tellurium are electrically connected in series. Configured.

  The performance of the thermo module 80 is determined by the performance and size of the P-type and N-type thermoelectric semiconductor elements 13 (13a, 13b) themselves, the logarithm of the thermoelectric semiconductor elements 13 to be incorporated, and the like.

  When a direct current is applied to the thermo module 80 through a lead wire 15 (or a metal post) described later, one end face (for example, the substrate 12) is cooled and the other end face (the substrate 11) is heated. There is a nature.

  Usually, a pattern (land portion 111) is formed on one surface (pattern surface) of a ceramic substrate 11 made of alumina or aluminum nitride by a method such as plating, and the P-type thermoelectric semiconductor element 13a and the N-type are formed on each independent land portion 111. A pair of thermoelectric semiconductor elements 13b are mounted.

  A similar pattern (land portion 121) is also formed on the other ceramic substrate 12, but this pattern is such that all the thermoelectric semiconductor elements 13a and 13b are arranged in series in electrical circuit after bonding. It is a pattern.

  Further, on one ceramic substrate (substrate 11 in this example), lead member mounting lands 112-1, 112- for attaching a power supply lead wire 15 or a metal post (not shown) to the thermo module 80. There are two.

  Usually, after a lead member such as a lead wire 15 or a metal post is attached to the lead member attachment lands 112-1 and 112-2, whether a desired temperature difference is generated by applying a predetermined current value, Tests have been conducted to determine if there is an abnormal increase in internal resistance by repeating several reverse energization cycles.

  In recent years, this type of thermo module 80 has been widely used for precise temperature control of a laser diode used for optical communication by utilizing the above-described properties (one substrate generates heat and the other substrate cools).

  In such an application, the thermo module 80 is usually housed in a low thermal expansion coefficient metal case called a butterfly PKG together with a laser diode, and the case and the heat radiation side substrate 11 of the thermo module 80 are soldered.

  In addition, the laser diode is directly attached to the upper side of the cooling side substrate 12 of the thermo module 80 by solder bonding or adhesive bonding, or is mounted on a heat spreader (metal having a low thermal expansion coefficient such as a copper-tungsten alloy) by solder bonding. It is done.

  On the other hand, in the thermo module 80, solder is also used for joining the P-type thermoelectric semiconductor elements 13 a and N-type thermoelectric semiconductor elements 13 b and the land portions 111 and 121 of the ceramic substrates 11 and 12.

  As the assembly solder in this case, lead tin eutectic solder (melting point 183 ° C.) or tin antimony solder (melting point 232 ° C.) is usually used.

  Therefore, when the thermo module 80 is to be incorporated into the package of the optical communication module, the solder used for joining the heat radiation side substrate 11 and the cooling side substrate 12 of the thermo module 80 to the package or heat spreader is the thermo module. It must have a lower melting point than 80 assembly solder.

  For example, in the thermo module 80 assembled with the latter tin antimony solder, solder having a melting point lower than that of lead tin eutectic solder can be used for bonding with a package or a heat spreader.

  On the other hand, in recent years, the lead-free solder has been taken up as one of the global environmental problems, and the realization of lead-free has become an issue in the optical communication field.

  Against this background, when the thermo module itself is assembled with tin antimony solder, lead free of the thermo module 80 has been achieved, but in order to achieve lead free of the entire package, both lead tin and tin There is a problem that only a part of low melting point solder such as indium tin solder can be used for bonding between a laser diode and a heat spreader and bonding between a heat spreader and a thermo module.

  Therefore, it is necessary to assemble the thermo module 80 with solder having a temperature higher than that of tin antimony solder and to increase the temperature range of the solder that can be used for the package.

  On the other hand, existing solder materials have a low Young's modulus and are easy to creep when used for a long time. This characteristic is that when materials with different coefficients of thermal expansion are combined, the solder layer becomes a cushioning material, and there is a merit that the deformation of the thermo module 80 is reduced, but there is also a demerit that it is gradually deformed over a long period of use. is there.

  In particular, the thermo-module 80 used for precise temperature control of the laser diode is likely to be deformed due to a temperature change, so that the optical axis shift of the laser diode is likely to develop. From this viewpoint, the optical axis shift of the laser diode is suppressed. In such a case, a solder material having a higher Young's modulus has been desired.

  As described above, the conventional thermo module generally joins the ceramic substrate and the P-type and N-type thermoelectric semiconductor elements using lead-tin eutectic solder, so that the temperature of the laser diode for optical communication is increased. In the case of using it regularly, there has been a problem that it becomes a hindrance to lead-free as seen from the whole optical communication module in which the module and the laser diode are mounted together.

  In addition, in this type of conventional thermo module, the lead-tin eutectic solder used as a bonding agent has a low Young's modulus, so the substrate easily deforms with respect to temperature changes, and the precise temperature of the laser diode of the optical communication module. In the case of using the laser diode, there is a problem that the optical axis shift of the laser diode easily occurs due to deformation due to temperature change.

  The present invention solves the above-mentioned problems and is a gold-tin junction Peltier useful for lead-free and prevention of optical axis misalignment of a laser diode when used for precise temperature control of the laser diode of an optical communication module. An object is to provide an element thermoelectric conversion module.

The invention according to claim 1 is a Peltier element thermoelectric conversion module,
A plurality of P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, a pair of ceramic substrates joined to upper and lower sides of the P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, and a lead member provided on one of the ceramic substrates The main component has a metal post for power supply joined to the metallization layer for mounting,
Gold and tin containing approximately 80% by weight of gold and tin having a eutectic composition are used for joining the metal post and the metallization layer for attaching the lead member of the one ceramic substrate. To do.

According to a second aspect of the present invention, a plurality of P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, a pair of ceramic substrates bonded to the upper and lower sides of the P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, and the ceramic The main component has a metal post for power supply joined to a metallization layer for mounting a lead member provided on one side of the substrate,
Gold-tin containing approximately 80 weight percent of gold that does not contain a lead component and has a higher Young's modulus than lead-tin in the joining of the metal post and the metallization layer for mounting the lead member of the one ceramic substrate In the manufacturing method of Peltier element thermoelectric conversion module using gold tin of eutectic composition,
After the metal post is joined to the metallization layer for attaching the lead member of the pair of ceramic substrates with the gold tin, the thermoelectric semiconductor elements are arranged and joined between the ceramic substrate and the other ceramic substrate, thereby connecting the thermoelectric semiconductor elements. Assembling the conversion module.

According to a third aspect of the present invention, there are provided a plurality of P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, a pair of ceramic substrates joined to both upper and lower sides of the P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, and the ceramic The main component has a metal post for power supply joined to a metallization layer for mounting a lead member provided on one side of the substrate,
Gold-tin containing approximately 80 weight percent of gold that does not contain a lead component and has a higher Young's modulus than lead-tin in the joining of the metal post and the metallization layer for mounting the lead member of the one ceramic substrate In the manufacturing method of Peltier element thermoelectric conversion module using gold tin of eutectic composition,
After assembling the thermoelectric conversion module by bonding the pair of ceramic substrates to the upper and lower sides of each thermoelectric semiconductor element, the metal post and the metallization layer for attaching the lead member of the one ceramic substrate are bonded. It is characterized by that.

The invention according to claim 4 is the invention according to claim 2 or 3, wherein
The gold-tin alloy layer having the gold-tin eutectic composition is electrolytically deposited on the joint surface of the metal post, and the alloy layer is used to form the metal post and the metallization layer for attaching the lead member of the one ceramic substrate. It is characterized by joining.

The invention according to claim 6 is an optical communication module,
A plurality of P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, a pair of ceramic substrates joined to upper and lower sides of the P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, and a lead member provided on one of the ceramic substrates It has a metal post for power supply joined to the metallization layer for mounting as a main component, and does not contain a lead component in the joint between the metal post and the metallization layer for mounting the lead member of the one ceramic substrate, and A Peltier element thermoelectric conversion module using gold tin of a gold tin eutectic composition containing approximately 80 weight percent of gold having a higher Young's modulus than lead tin;
A laser diode controlled to a target temperature by the Peltier element thermoelectric conversion module;
With the inside of the package,
The laser diode is attached to the Peltier element thermoelectric conversion module through solder which does not contain lead and has a lower melting point than gold tin.

The figure which shows the conceptual side structure of the gold tin joining Peltier device thermoelectric conversion module concerning this invention. FIG. 3 is a diagram illustrating a thermoelectric semiconductor element generation process according to the first embodiment. The figure which shows the structure of the metallization layer formed in a ceramic substrate. FIG. 3 is a diagram illustrating a module assembly process according to the first embodiment. The figure which shows the module assembly process following the process in FIG. FIG. 10 is a diagram illustrating a module assembly process according to the second embodiment. The figure which shows the module assembly process following the process in FIG. FIG. 5 is a diagram showing a thermoelectric semiconductor element generation process according to the third embodiment. FIG. 10 is a diagram illustrating a module assembly process according to the third embodiment. The figure which shows the module assembly process following the process in FIG. FIG. 10 is a diagram showing a thermoelectric semiconductor element generation step according to Example 4; FIG. 10 is a diagram showing a thermoelectric semiconductor element generation process according to the fifth embodiment. FIG. 10 is a diagram showing a thermoelectric semiconductor element generation step according to Example 6; FIG. 10 is a diagram showing a thermoelectric semiconductor element generation step according to Example 7. The figure which shows the state which observed the joining state of the thermomodule obtained in Example 7 from the side surface. The figure which shows the state which observed the joining state of the thermomodule obtained in Example 2 from the side surface. The figure which shows the gold tin layer formation process to the thermoelectric semiconductor element outermost surface concerning Example 8. FIG. FIG. 10 is a diagram showing a thermoelectric semiconductor element generation step according to Example 9; The conceptual diagram which shows the surface state of the gold tin foil fusion | melting thermoelectric semiconductor wafer concerning Example 10. FIG. FIG. 10 is a diagram showing a thermoelectric semiconductor element generation step according to Example 10. FIG. 18 is a diagram showing a module assembly process according to the twelfth embodiment. FIG. 20 is a diagram showing a module assembly process according to Embodiment 13; FIG. 19 is a conceptual diagram showing a lead wire attaching process according to Example 16; FIG. 20 is a conceptual diagram showing a post attachment process according to Example 19; The figure which shows an example of the post joining in Example 21, and a module assembly process. The figure which shows another example of the post joining in Example 21, and a module assembly process. The figure which shows the structure of the optical communication module formed by mounting the thermomodule of this invention. The conceptual diagram which shows the general structure of a thermomodule.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  In view of the problems listed in the column of problems to be solved by the present invention, the present inventor, in particular, on the premise of a thermo module used for precise temperature control of a laser diode of an optical communication module, leads free of the entire optical communication module. From the standpoint of making the optical axis of the laser diode and the laser diode optically stable, we have intensively researched and established a practical method of gold-tin eutectic solder with a gold content of 80 weight percent and a melting point of 280 ° C. suitable for assembling the thermo module.

  FIG. 1 is a diagram showing a conceptual side structure of a gold-tin bonded Peltier element thermoelectric conversion module (hereinafter abbreviated as a gold-tin bonded thermo module) 10 manufactured according to the present invention.

  This gold-tin bonded thermomodule 10 has a structure in which a plurality of pairs of P-type thermoelectric semiconductor elements 13a and N-type thermoelectric semiconductor elements 13b are bonded between a ceramic substrate 11 on the heat dissipation side and a ceramic substrate 12 on the cooling side. Yes.

  On one surface (pattern surface) of the ceramic substrates 11 and 12, a plurality of independent land portions (metallized layers) 111 and 121 are formed by a printing pattern, for example.

  Each pair of P-type thermoelectric semiconductor element 13 a and N-type thermoelectric semiconductor element 13 b is disposed on a corresponding land portion 111 on the pattern surface of the ceramic substrate 11.

  The other ceramic substrate 12 is inverted so that its pattern surface faces the surface of the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b (the side not joined to the land portion 111 of the ceramic substrate 11). Each pair of P-type thermoelectric semiconductor elements 13 a and N-type thermoelectric semiconductor elements 13 b is aligned to be arranged in each land portion 121 on the pattern surface, and is arranged opposite to the ceramic substrate 11.

  Here, in the land portion 111 of the ceramic substrate 11 and the land portion 121 of the ceramic substrate 12, all the thermoelectric semiconductor elements 13 (13 a, 13 b) are connected in series in an electric circuit in the above-described opposed arrangement state. They are formed in an array pattern whose positions are shifted from each other.

  In other words, in the gold-tin bonded thermomodule 10, a plurality of P-type thermoelectric semiconductor elements 13a and N-type thermoelectric semiconductor elements 13b are alternately arranged vertically and horizontally between the ceramic substrate 11 and the ceramic substrate 12 disposed opposite thereto. And electrically connected in series via the land portions 111 and 121 of the ceramic substrates 11 and 12.

  In the gold-tin bonded thermomodule 10 of the present invention having such an arrangement, each pair of P-type thermoelectric semiconductor elements 13a and N-type thermoelectric semiconductor elements 13b and ceramic substrates 11 arranged to face each other with these elements 13a and 13b interposed therebetween. The land portion 111 and the land portion 121 of the ceramic substrate 12 are joined by gold tin layers 113 and 123, respectively.

  In the present invention, as the gold-tin layers 113 and 123, gold-tin eutectic composition solder having a gold content of approximately 80 weight percent is used.

  Further, a pair of lead wire mounting land portions 112a-1 and 112a-2 (112a-2 does not appear in the figure) separately from the land portion 111 for mounting the thermoelectric semiconductor element at the end of the pattern surface of the ceramic substrate 11. Is formed.

  A pair of lead wires 15 that are connected to a positive electrode and a negative electrode of a power source (not shown) and supply power to the gold-tin bonded thermo module 10 are bonded to the lead wire mounting lands 112a-1 and 112a-2. Yes.

  In the present invention, gold-tin eutectic solder having a gold content of approximately 80 weight percent is also used for joining the lead wire 15 to the lead wire mounting lands 112a-1 and 112a-2.

  In this gold-tin bonded thermomodule 10, a metal prism called a post may be used instead of the lead wire 15. In this case, post mounting land portions 112b-1, 112b-2 (see FIGS. 24, 25, 26) are formed in place of the lead wire mounting land portions 112a-1, 112a-2, and the post is It is possible to join the post mounting land portions 112b-1 and 112b-2 using gold tin solder having the eutectic composition of the above ratio.

  When a direct current is passed from the power source in the direction from the N-type thermoelectric semiconductor element 13b to the P-type thermoelectric semiconductor element 13a, the upper ceramic substrate 12 is cooled and the lower-side ceramic substrate 12 is cooled. The ceramic substrate 11 operates to generate heat.

  On the back surface (non-pattern surface) side of the pattern surface of the ceramic substrate 11, a back surface metallized layer 114 for bonding with a heat dissipation object is formed, and on the back surface (non-pattern surface) side of the pattern surface of the ceramic substrate 12. Is formed with a back metallized layer 124 for bonding to the object to be cooled.

  As described above, the gold-tin bonded thermo module 10 according to the present invention mainly includes the ceramic substrates 11 and 12, the P-type thermoelectric semiconductor element 13a, the N-type thermoelectric semiconductor element 13b, and the power supply lead wire 15 (or metal post). In the thermo module as a constituent element, gold-tin eutectic composition solder having a gold content of approximately 80 weight percent is used for bonding between the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b and the ceramic substrates 11 and 12. It was.

  Here, an outline of the present invention will be described.

  First, the present inventor uses gold-tin eutectic solder having a melting point of 280 ° C. and a gold content of 80 weight percent as the assembly solder for the gold-tin bonded thermo module 10 described above. Was examined.

  The simplest method is a method in which gold-tin paste is applied to the mounting positions (land portions 111, 121) of the P-type thermoelectric semiconductor elements 13a and N-type thermoelectric semiconductor elements 13b on the ceramic substrates 11, 12 by a printing method or a dispenser. However, since the metallized outermost surfaces of the land portions 111 and 121 are usually gold-plated, the molten gold tin solder flows to the side surfaces of the land portions 111 and 121, so there is a risk of a short circuit.

  In order to avoid this inconvenience, only the surface on which the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b are mounted is gold-plated, and the other side is left as a metal surface such as copper which is difficult to form an alloy with gold. There is a need to. This can be achieved by switching the method for producing the ceramic substrates 11 and 12 from the subtractive method to the semi-additive method.

  Next, a simple method is to finish the outer surfaces of the ceramic substrates 11 and 12 and the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b with a gold finish between them and sandwich a gold-tin pellet with a predetermined gold content between them. How to wear.

  This method is effective for a thermomodule in which the size of the thermoelectric semiconductor elements 13a and 13b is relatively large, but is optimal for assembling a thermomodule using the thermoelectric semiconductor elements 13a and 13b having a minute size of less than 1 mm square. It's not a method.

  That is, in order to place gold-tin pellets less than 1 mm square at predetermined positions without misalignment, and to stand and join the thermoelectric semiconductor elements 13a and 13b thereon, it is essential to develop a jig for preventing misalignment. Because it is not suitable for mass production.

  However, if the high-viscosity flux is used well, the gold-tin pellet can be fixed to the land portions 111 and 121 of the ceramic substrates 11 and 12 almost accurately, and the thermoelectric semiconductor elements 13a and 13b are positioned at predetermined positions on the metal plate. It is determined that gold-tin bonding can be achieved by this method if a hole is formed and positioned.

  As a more advanced method, there is a method in which a gold tin layer (113, 123) having a predetermined composition is deposited on the outermost surfaces of the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b.

  In the method of forming the gold tin layer (113, 123) by plating, the deposition is performed while applying an electric field from a predetermined solution to the semiconductor element surface, so that the variation in the thickness of the deposited layer in the deposited surface is made uniform. In addition, it is necessary that there is no variation in the gold-tin composition with a gold content of 80 weight percent.

  Although complicated in terms of process, the outermost surfaces of P-type and N-type thermoelectric semiconductor blocks (corresponding to ingots to be described later) are gold-plated, and then gold tin foil or foil having a predetermined gold content is melted in advance on this block. Then, by dicing the block, P-type thermoelectric semiconductor elements 13a and N-type thermoelectric semiconductor elements 13b are generated, and these thermoelectric semiconductor elements 13a and 13b are formed on the gold-finished ceramic substrates 11 and 12, respectively. There is a method in which the land portions 111 and 121 are arranged and heated and fused.

  As described above, this method also has a problem with the positioning accuracy of the thermoelectric semiconductor elements 13a and 13b. However, it is considered that this method can also be realized by using a high-viscosity flux for fixing.

  With respect to the above-mentioned problems, it was determined that the gold-tin bonded thermomodule 10 could be put into practical use by taking the measures described below, and various experiments were conducted to arrive at the present invention.

  Further, when the thermo module 10 is assembled by gold-tin bonding, the use of tin antimony solder having a low melting point for bonding of the power supply lead wire 15 or a metal post instead thereof has the effect of lead-free. Since it is scarce, we have accumulated a lot of diligent experiments to arrive at a practical lead member joining method.

  Hereinafter, typical examples will be described in detail.

Example 1
In this example, first, the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b were generated through the steps shown in FIG.

  First, respective ingots (thermoelectric semiconductor blocks) 70 were formed while heating and pressurizing P-type and N-type thermoelectric semiconductor powders mainly composed of bismuth-tellurium.

  Next, each ingot 70 was sliced, and P-type and N-type thermoelectric semiconductor wafers 71 were obtained. A wafer size of approximately 30 mm × 40 mm and a thickness of approximately 0.8 mm were prepared depending on the module performance.

  The P-type thermoelectric semiconductor wafer 71 and the N-type thermoelectric semiconductor wafer 71 were each etched with a mixed acid of an inorganic acid, and electroless nickel plating was applied to the entire circumference of the wafer 71 to a thickness of approximately 4 μm.

  Thereafter, 0.2 to 0.3 μm of gold plating was applied. In this state, the wafer 71 was fixed to a jig, and dicing was performed to obtain a P-type thermoelectric semiconductor element 13a and an N-type thermoelectric semiconductor element 13b. The element size of the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b after chopping is 0.64 mm × 0.64 mm.

  The assembly of the thermo module using the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b obtained by the above steps was performed through a series of steps shown in FIGS.

  First, as shown in FIG. 4A, a gold-tin paste was applied to the land portion 111 of the ceramic substrate 11. The gold-tin paste used is a commercial product, which is a gold-tin alloy having a eutectic composition in which the gold content in the metal component is approximately 80 weight percent. This paste contains gold-tin particles having a particle size of 25 to 32 μm and RMA type flux.

  The ceramic substrate 11 used (similar to the ceramic substrate 12 but without the lead wire mounting land) is made of alumina having a thickness of 0.3 mm, and one surface thereof is made of P-type thermoelectric semiconductor element 13a and N-type thermoelectric. Only 31 land portions 111 are arranged so that semiconductor elements 13b can be arranged one by one, and lead wire mounting land portions 112a-1 and 112a-2 for mounting power supply lead wires 15 (FIG. 4). Then, it is omitted for simplification).

  As shown in FIG. 3, the structure of the land portion 111 (the same applies to the land portion 112 of the ceramic substrate 12) includes a copper metallized layer 1111 from the ceramic side, a nickel metallized layer 1112 on the copper metallized layer 1112, and gold on the top. The side wall of each land 111 has a bare structure of copper, nickel, and gold.

  The back surface of the element mounting surface of the ceramic substrate 11 is metalized 0.1 mm smaller than the outer peripheral portion of the ceramic substrate 11, and copper (copper metallized layer 1141), nickel (nickel metallized layer 1142), gold (gold plating 1143) over the entire surface. And a metallized structure (back metallized layer 114).

  In the gold-tin paste application process shown in FIG. 4A, a metal mask having holes at the same position as the pattern (land portion 111) is covered with the pattern surface of the ceramic substrate 11, and the gold mask is applied from above. Tin paste was squeezed.

  Excessive gold-tin paste was removed with a metal spatula so as to obtain a uniform thickness, and approximately 50 μm of gold-tin paste was applied.

  After removing the metal mask, the thermoelectric semiconductor elements 13a and 13b having the gold plating finish produced by the method shown in FIG. Were arranged [see FIG. 4 (b)].

  In this state, a weight for preventing misalignment was placed, placed in a vacuum furnace, heated to 320 ° C. at a heating rate of 10 ° C./min and held for 1 minute to perform gold-tin bonding [FIG. c)].

  The obtained π set state module in which only one of the ceramic substrate 11 and the thermoelectric semiconductor elements 13a and 13b was joined did not flow out of gold tin, and the joined state was good.

  Next, as shown in FIG. 5A, the other ceramic substrate 12 is also coated with a gold-tin paste on the land portion 121 in the same manner, and the gold surface element of the π set state module ( It overlapped with the thermoelectric semiconductor elements 13a and 13b) side.

  Thereafter, the process proceeds to a heating step as shown in FIG. 5B. Here, instead of the carbon jig, the entire module (the entire module in a state of being assembled in both sets) is sandwiched between metal plates and heated in a vacuum furnace. The heating conditions were the same as those at the time of generating the above-described π set state module [see FIG. 4 (c)].

  The gold-tin bonded thermo module 10 obtained through the above steps measures the internal resistance (R1) after the lead wire is attached, and then performs a thermal shock test at -40 ° C / 85 ° C (30 minutes / cycle, 20 cycles). And a reverse energization test (current was applied so that the temperature difference between the cooling side and the heat radiation side would be 70 to 75 ° C., switching for 7.5 seconds, 72 cycles).

  As a result of measuring the internal resistance (R2) after the test and determining the resistance change rate, it was confirmed that all the thermo modules had an internal resistance change rate of about 0.5% and functioned sufficiently as a thermo module.

  Therefore, it was confirmed that the assembly of the thermo module 10 using the gold tin paste was effective.

Example 2
Also in this example, the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b were generated through the steps shown in FIG.

  First, each ingot 70 was produced, heating and pressurizing the P-type and N-type thermoelectric semiconductor powder which have bismuth-tellurium as a main component. Each ingot 70 was sliced to obtain a P-type thermoelectric semiconductor wafer 71 and an N-type thermoelectric semiconductor wafer 71. The wafer size was approximately 30mm x 40mm and the thickness was approximately 0.8mm depending on the module performance.

  The wafer 71 was made into a P-type thermoelectric semiconductor element 13a and an N-type thermoelectric semiconductor element 13b with gold plating by the same method as in Example 1 (see FIG. 2), and each was mounted on a fixing jig to a size of 0.64 mm × 0.64 mm. Dicing.

  The ceramic substrate 11 used for assembling the thermo module in the present embodiment (the same applies to the ceramic plate 12, but without the lead wire mounting land portion) is made of alumina having a thickness of 0.3 mm, and one surface thereof is P-type. Thirty-one land portions 111 are formed so that one thermoelectric semiconductor element 13a and one N-type thermoelectric semiconductor element 13b can be arranged, and further, a lead wire mounting land portion 112a-1 for mounting a power supply lead wire 15 is provided. , 112a-2 are formed.

  The structure of the land portion 111 on the ceramic substrate 11 (the same applies to the land portion 112 of the ceramic substrate 12) consists of a copper metallized layer from the ceramic side, a nickel metallized layer on the copper metallized layer, and gold on the layer 0.2 to 0.3 μm. It is a plated structure, and the side wall of each land part 111 has a structure in which copper, nickel, and gold are exposed (see FIG. 3).

  The surface opposite to the pattern surface of the ceramic substrates 11 and 12 is metallized 0.1 mm smaller than the outer periphery of the ceramic substrates 11 and 12, and has a metallized structure made of copper, nickel, and gold over the entire surface (see FIG. 3). ).

  In this embodiment, the gold-tin junction thermomodule 10 is assembled through the series of steps shown in FIGS. 6 and 7 using the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b and the ceramic substrates 11 and 12 described above. Was done.

  First, as shown in FIG. 6A, a highly viscous flux was applied to the pattern (land portion 111) of the ceramic substrate 11.

  After that, a carbon mask having a hole at the same position as the land portion 111 is covered, and a gold tin foil (thickness: 35 μm) punched out to approximately the same size (0.7 mm square) as the thermoelectric semiconductor elements 13a and 13b is placed thereon. It was made to adhere [refer FIG.6 (b)].

  Next, as shown in FIG. 6C, after arranging the gold-plated thermoelectric semiconductor elements 13a and 13b on the gold tin foil using a carbon jig, as shown in FIG. It was heated and melted using a vacuum furnace with a weight to prevent misalignment.

  As heating conditions, gold-tin bonding was performed by heating to 320 ° C. at a temperature rising rate of 10 ° C./min and holding for 1 minute. The obtained π set state module in which only one of the ceramic substrate 11 and the thermoelectric semiconductor elements 13a and 13b was joined did not flow out of gold tin, and the joined state was good.

  Next, the carbon jig is removed and, as shown in FIG. 7 (a), gold-tin foil is attached to the gold-plated finish surface of the thermoelectric semiconductor elements 13a and 13b that have not been bonded using a high-viscosity flux. After stacking the other ceramic substrate 12, as shown in FIG. 7B, it was fixed to a metal jig for preventing misalignment and heated and melted in a vacuum furnace.

  The heating conditions were the same as those at the time of generating the above-described π set state module [see FIG. 6 (d)].

  A thermocouple is bonded to one surface of the gold-tin bonded thermo module 10 thus created with lead tin solder, the other surface is set on a temperature-controlled water-cooled plate, and a thermocouple is attached to the cooling surface. It was confirmed that when the maximum current (about 1.2 A) was applied to the module 10, a temperature difference of about 70 ° C. appeared between the cooling side substrate 11 and the heat radiation side substrate 12. Therefore, it was confirmed that the thermo module 10 using gold-tin pellets (foil) can be sufficiently assembled.

Example 3
In this example, the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b were generated through the steps shown in FIG.

  First, each ingot 70 (refer FIG. 2) was created, heating and pressurizing the P-type and N-type thermoelectric semiconductor powder which have bismuth-tellurium as a main component. Each ingot 70 was sliced to obtain a P-type thermoelectric semiconductor wafer 71 and an N-type thermoelectric semiconductor wafer 71. The wafer size was approximately 30mm x 40mm and the thickness was approximately 0.8mm depending on the module performance.

  In order to ensure adhesion, the P-type thermoelectric semiconductor wafer 71 and the N-type thermoelectric semiconductor wafer 71 were each etched with a mixed acid of an inorganic acid, and then electroless nickel plating was applied to the entire circumference of the wafer to a thickness of approximately 4 μm. Thereafter, 0.2 to 0.3 μm of gold plating was applied.

  Next, a gold tin foil (foil) having a thickness of 35 μm was thermally fused to the gold-plated wafer under a reducing atmosphere (high-purity nitrogen gas added with a trace amount of hydrogen gas). The size of the gold tin foil used was 15 mm × 40 mm, and two of these were arranged on one side of the wafer 71 and fused. The heating conditions were heating to 320 ° C. at a rate of temperature increase of 10 ° C./min, and holding at that temperature for 1 minute. The cooling rate was 10 ° C./min.

  Next, the obtained gold-tin fusion wafer 71 was fixed to a jig and diced to a size of 0.64 mm × 0.64 mm to obtain a P-type thermoelectric semiconductor element 13a and an N-type thermoelectric semiconductor element 13b.

  The ceramic substrate 11 used for assembling the thermo module of the present embodiment (the ceramic plate 12 is the same, but the lead wire mounting land portion is not provided) is made of alumina having a thickness of 0.3 mm, and one surface thereof is a P-type thermoelectric. Only 31 pairs of land portions 111 are formed so that one semiconductor element 13a and one N-type thermoelectric semiconductor element 13b can be arranged, and lead wire attaching land portions 112a-1 and 112a for attaching power supply lead wires. -2 is a pattern.

  The structure of the land portion 111 of the ceramic substrate 11 (the same applies to the land portion 121 of the ceramic substrate 12) is a structure in which a copper metallized layer, a nickel metallized layer thereon, and gold plated thereon is 0.2 to 0.3 μm. Yes, the side walls of each pattern (land portions 111 and 121) are exposed from copper, nickel, and gold (see FIG. 3).

  Further, the surface opposite to the pattern surface (element mounting surface) of the ceramic substrate 11 has a metallized structure made of copper, nickel, and gold over the entire surface 0.1 mm smaller than the outer peripheral portion of the ceramic substrate 11 (see FIG. 3). .

  In the present embodiment, the assembly of the gold-tin bonding thermomodule 10 is performed through the series of steps shown in FIGS. 9 and 10 using the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b and the ceramic substrates 11 and 12 described above. Performed in air.

  Specifically, a high-viscosity flux is applied to the land portion 111 of the pattern surface of the ceramic substrate 11 (see FIG. 9A), and then a P-type thermoelectric semiconductor element 13a in which gold tin is fused thereon, N-type thermoelectric semiconductor elements 13b were arranged (see FIG. 9B), and further, gold-tin bonding was performed at a heating part set temperature of 390 ° C. for 20 seconds (see FIG. 9C).

  The π group state module in which only one of the ceramic substrate 11 and the thermoelectric semiconductor elements 13a and 13b obtained through the above-described steps is bonded has good wetting of the gold tin to the ceramic substrate 11 and the bonding state is good. .

  Next, another ceramic substrate 12 is overlaid on the above-mentioned π set state module (see FIG. 10A), and further heated at 345 ° C. for 3 minutes together with the fixing jig [FIG. )], A gold-tin bonded thermo module 10 was obtained.

  The obtained thermo module 10 measures the internal resistance (R1) after the lead wire 15 is attached, and then performs a thermal shock test and a reverse energization test (cooling side) at -40 ° C / 85 ° C (30 minutes / cycle, 20 cycles). / Current was applied so that the temperature difference on the heat radiation side would be 70 to 75 ° C, switching for 7.5 seconds, and 72 cycles).

  As a result of measuring the internal resistance (R2) after the test and determining the rate of change in resistance, it was confirmed that all the thermo modules 10 increased by about 0.5% and functioned satisfactorily as the thermo module 10.

  From the above, a gold-tin layer having a eutectic composition containing about 80 weight percent of gold is provided on the outermost surfaces of the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b, and the thermomodule 10 is assembled using this as a bonding agent. It was confirmed that this was also possible.

Example 4
In this example, the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b were generated through the steps shown in FIG.

  First, each ingot 70 (refer FIG. 2) is produced, heating and pressurizing the P-type and N-type thermoelectric semiconductor powder which has bismuth-tellurium as a main component, and each ingot 70 is sliced, P-type thermoelectric semiconductor A wafer 71 and an N-type thermoelectric semiconductor wafer 71 were obtained. The wafer size was approximately 30 mm x 40 mm, and the thickness was approximately 0.8 mm from the module performance.

  P-type thermoelectric semiconductor wafer 71 and N-type thermoelectric semiconductor wafer 71 were each etched with a mixed acid of an inorganic acid, and then electroless nickel plating was applied to the entire circumference of the wafer by 4 μm.

  Thereafter, a gold-plated finished wafer with gold plating equivalent to flash gold (0.01 μm by fluorescent X-ray film thickness measurement), 0.2 to 0.3 μm, 5 μm, 10 μm, and 20 μm (observation of resin embedded cross section after dicing) was made as a prototype. For comparison, a level (not shown) stopped by nickel plating was also prototyped.

  Next, a gold tin foil (foil) having a thickness of 35 μm was placed on both surfaces of each gold-plated wafer and a nickel-plated wafer, and fused using a vacuum furnace. As in the case of Example 3, the fusing conditions are maintained at 320 ° C. for 1 minute in a reducing atmosphere.

  In such a process, gold tin tended to spread more than the original area on a gold-plated wafer, but no spread was seen on a nickel-plated wafer alone, and nickel and gold-tin foil were joined. Was insufficient.

  Thereafter, each wafer was diced into 0.64 mm × 0.64 mm square to obtain a P-type thermoelectric semiconductor element 13a and an N-type thermoelectric semiconductor element 13b. In this process, there was no problem with the gold-plated wafer, but with the nickel-plated wafer, the gold-tin layer was partially peeled during dicing, and could not be used for module assembly.

  The assembly of the thermomodule in the present example was performed using an alumina substrate having 23 pairs of land portions. Specifically, using an assembly automatic machine, a high-viscosity flux is applied to an alumina substrate, and a P-type thermoelectric semiconductor element 13a and an N-type thermoelectric semiconductor element 13b for each gold plating level are arranged on the alumina substrate. A π group state module was obtained under heating conditions of seconds.

  Thereafter, another ceramic substrate was superposed on the substrate of the π group state module, and heated while being sandwiched between the jigs for both groups, so that a gold-tin bonded thermomodule 10 composed of 23 thermoelectric semiconductor element pairs was obtained.

  After assembly is completed, lead wires are attached and the internal resistance (R1) is measured, and then a thermal shock test and reverse energization test (cooling / heat dissipation side) at -40 ° C / 85 ° C (30 minutes / cycle, 20 cycles) Current application, 7.5 second switching, 72 cycles) were performed so that the ultimate temperature was 70 to 75 ° C.

  As a result of measuring the internal resistance (R2) after the test and determining the rate of change in resistance, it was confirmed that all the thermo modules increased by about 0.5% and functioned satisfactorily as thermo modules.

  Thereafter, a copper tungsten (20%) plate having a thickness of 1 mm was bonded to both sides of the thermo module using tin silver copper solder (melting point: 217 ° C.). As a result of evaluating the durability of the sample thus prepared by the thermal shock test, the change in resistance value after the end of 1000 cycles varied depending on the thickness of the gold plating.

  The resistance value change amount was the largest at the gold plating level of 0.01 μm, and the other gold plating levels were almost the same level. The gold plating level of 0.01 μm reached an internal resistance change rate of 5% in about 100 cycles, while the other levels had an internal resistance change rate of less than 2% even after 1000 cycles.

  Therefore, when the gold tin foil is fused to the thermoelectric semiconductor wafer, it is necessary to apply gold plating to the outermost surface of the wafer, and preferably to apply gold plating of 0.01 μm or more.

Example 5
In this example, the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b were generated through the steps shown in FIG.

  First, each ingot 70 (refer FIG. 2) is produced, heating and pressurizing the P-type and N-type thermoelectric semiconductor powder which has bismuth-tellurium as a main component, and each ingot 70 is sliced, P-type thermoelectric semiconductor A wafer 71 and an N-type thermoelectric semiconductor wafer 71 were obtained. A wafer size of approximately 30 mm × 40 mm and a thickness of approximately 0.8 mm were prepared depending on the module performance.

  The P-type thermoelectric semiconductor wafer 71 and the N-type thermoelectric semiconductor wafer 71 were each etched with a mixed acid of an inorganic acid, and then electroless nickel plating was applied to the entire circumference of the wafer to a thickness of approximately 4 μm.

  After that, a prototype with a tin plating layer of 1 μm and 2 μm attached to the outermost surface of the wafer 71 was made as a prototype, and a standard with nickel plating was made for comparison.

  A 35 μm-thick gold tin foil was sandwiched between both surfaces of each surface-treated wafer, and fusion with a gold tin foil (foil) was attempted under a heating condition of 320 ° C. × 1 minute held in a reducing atmosphere vacuum furnace.

  Each wafer was diced into 0.64 mm × 0.64 mm squares by dicing, but the wafers with gold tin foil fused to the nickel plating finish showed partial peeling of the gold tin layer during dicing. The wafer that had undergone tin plating was in close contact with the thermoelectric semiconductor and no delamination was observed.

  The gold-tin bonded thermomodule 10 was assembled in the same manner as in Example 4 using the tin-plated thermoelectric semiconductor elements 13a and 13b that were found to be assembled by the above observation. As a result, the melting point of gold tin did not change significantly, and the adhesion between the element and the substrate was good even in a destructive test after module assembly.

  After attaching the lead wire to the gold-tin bonded thermo module 10 after assembly, the rate of change in resistance before and after the thermal shock test and reverse current test is 0.3 to 0.6 percent for both gold plating and tin plating finishes. It was the same level as when using solder of type.

Example 6
In this example, the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b were generated through the steps shown in FIG.

  First, each ingot 70 (refer FIG. 2) is produced, heating and pressurizing the P-type and N-type thermoelectric semiconductor powder which has bismuth-tellurium as a main component, and each ingot 70 is sliced, P-type thermoelectric semiconductor A wafer 71 and an N-type thermoelectric semiconductor wafer 71 were obtained. The wafer size was approximately 30 mm x 40 mm, and the thickness was approximately 0.8 mm from the module performance.

  P-type thermoelectric semiconductor wafer 71 and N-type thermoelectric semiconductor wafer 71 were each etched with a mixed acid of an inorganic acid, and then electroless nickel plating was applied to the entire circumference of the wafer by 4 μm. Thereafter, gold plating was further attached to 0.2 to 0.3 μm, and a gold-plated finished wafer was prototyped.

  Both surfaces of the gold-plated finished wafer were fused using a gold tin foil (foil) having a predetermined thickness and a vacuum furnace. The prepared gold-tin foil thicknesses are 20μm, 35μm, 50μm, and 60μm. After fusion, they are diced into 0.64mm × 0.64mm square, and a gold-tin bonded thermo module using an alumina substrate with 23 pairs of lands. It was set to 10.

  Then, after conducting a thermal shock test and a reverse current test, a copper tungsten (20%) plate having a thickness of 1 mm was joined to both sides of the thermo module using tin silver copper solder.

  As a result of evaluating the durability of the sample thus prepared by the thermal shock test, the change in resistance value after the end of 1000 cycles varied depending on the thickness of the gold tin foil used for fusion.

  As a result, the rate of change in internal resistance tended to be smaller when thin gold tin was used than when thick gold tin foil was used. Also, when 60μm gold tin foil is used, excess gold tin accumulates between the P-type thermoelectric semiconductor element and N-type thermoelectric semiconductor element when the thermo module is assembled. If a thicker gold tin foil is used, a short circuit occurs during assembly. It became clear that there was a possibility of.

  Therefore, as a practical range, it was judged that good results can be obtained by fusing a gold tin foil of 20 μm to 60 μm.

Example 7
In this example, the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b were generated through the steps shown in FIG.

  First, each ingot 70 (refer FIG. 2) was created, heating and pressurizing the P-type and N-type thermoelectric semiconductor powder which have bismuth-tellurium as a main component. Each ingot 70 was sliced to obtain a P-type thermoelectric semiconductor wafer 71 and an N-type thermoelectric semiconductor wafer 71. A wafer size of approximately 30 mm × 40 mm and a thickness of approximately 0.8 mm were prepared depending on the module performance.

  The P-type thermoelectric semiconductor wafer 71 and the N-type thermoelectric semiconductor wafer 71 were each etched with a mixed acid of an inorganic acid, and then electroless nickel plating was applied to the entire circumference of the wafer 71 to a thickness of about 4 μm.

  Thereafter, a gold-tin alloy layer was deposited on nickel using a commercially available gold-tin plating solution. As a preliminary test, the gold tin layer was deposited so as to have a thickness of 5 μm, and the film thickness and component analysis were performed with fluorescent X-rays.

  When the thickness was about 5 μm, the thickness of the deposited gold-tin layer was almost uniform, but the composition was from 80/20, which was aimed at a gold / tin ratio, to a gold-rich 90/10.

  Thereafter, the composition of the electrolytic solution was changed, and a gold / tin composition with an aim of 80/20 was deposited, and a prototype was made with a thickness of 35 μm. When the thickness of the deposited gold-tin layer was about 35 μm, the wafer center portion was about 35 μm, whereas the wafer outer peripheral portion was about 60 μm thick.

  A wafer (see FIG. 14) whose outermost surface is coated with a gold-tin layer by electroforming is diced to a size of 0.64 mm × 0.64 mm, and the P-type thermoelectric semiconductor element 13a and N-type thermoelectric semiconductor element thus obtained are used. The gold-tin bonded thermo module 10 was assembled.

  The ceramic substrate 11 used for assembly in this example is made of alumina having a thickness of 0.3 mm, and a land on which one P-type thermoelectric semiconductor element 13a and one N-type thermoelectric semiconductor element 13b can be mounted on one side. 18 pairs of portions 111 are formed (18 pairs of land portions 121 are also formed on the other ceramic substrate 12), and lead wire mounting land portions 112a-1 and 112a-2 for further attaching lead wires 15 for power supply. Is formed as a pattern.

  The structure of the land portion 111 (the same applies to the land portion 121 on the other substrate 12) is that a copper metallized layer is formed from the ceramic substrate side, a nickel metallized layer is formed on the copper metallized layer, and gold is further 0.25 to 0.35 μm plated thereon. (See FIG. 3).

  The opposite surfaces of the pattern surfaces (element mounting surfaces) of the ceramic substrates 11 and 12 have a metallized structure made of copper, nickel, and gold over the entire surface 0.1 mm smaller than the outer peripheral portions of the ceramic substrates 11 and 12 (FIG. 3). reference).

  The assembly of the thermo module in this example was performed in the air using an automatic machine. Specifically, a P-type thermoelectric semiconductor element 13a and N are formed by applying a high-viscosity flux to the land portion 111 on the pattern side of the ceramic substrate 11, and then fusing gold tin on the land portion 111 using the deposition method shown in FIG. The type thermoelectric semiconductor elements 13b were arranged and joined at a heating part set temperature of 400 ° C. for 20 seconds.

  In the π set state module in which only one end face of the ceramic substrate 11 and the thermoelectric semiconductor elements 13a and 13b obtained in the above process was joined, the wettability was uneven by each land portion 111. This is presumed to be due to variations in the thickness of the gold-tin layer deposited on the thermoelectric semiconductor elements 13a and 13b described above.

  Next, the other ceramic substrate 12 and the π pair state module were superposed on each other and heated together with a fixing jig at 360 ° C. for 3 minutes to obtain a gold-tin bonded thermo module 10.

  The obtained thermo module 10 was lead-wired, and the resistance change rate of the thermo module 10 before and after the thermal shock test and the reverse current test was 0.7% at maximum, and it was confirmed that the thermo module 10 functions.

  Thereafter, the thermo module 10 was embedded in an epoxy resin and polished to confirm the bonding state. FIG. 15 is a view of the bonding state observed from the side.

  For comparison, FIG. 16 shows the observation results of the bonding state of the thermomodule 10 created in Example 2 under the same conditions (epoxy resin embedding and polishing).

Example 8
In this embodiment, after producing the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b through the steps shown in FIG. 2, a gold tin layer is formed on the outermost surfaces of these thermoelectric semiconductor elements 13a and 13b. Yes.

  First, respective ingots 70 were prepared while heating and pressurizing P-type and N-type thermoelectric semiconductor powders mainly composed of bismuth-tellurium. Each ingot 70 was sliced to obtain a P-type thermoelectric semiconductor wafer 71 and an N-type thermoelectric semiconductor wafer 71. A wafer size of approximately 30 mm × 40 mm and a thickness of approximately 0.8 mm were prepared depending on the module performance.

  Thereafter, these wafers 71 are etched, then electroless nickel plating (4 μm) is applied over the entire circumference of the wafer, and gold plating is further added to 0.2 to 0.3 μm.

  The P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b are mounted by attaching the gold-plated P-type thermoelectric semiconductor wafer 71 and the N-type thermoelectric semiconductor wafer 71 to a fixing jig and dicing into 0.64 mm × 0.64 mm square. (See FIG. 2 above).

  Furthermore, fusion of the gold tin foil to the outermost surfaces of the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b was performed using a carbon jig.

  For example, as shown in FIG. 17A, the carbon jig has a structure in which a carbon plate 171 having a thickness of about 5 mm is provided with a number of reamer holes 172 having a depth of 1 mm and φ1.

  As shown in FIG. 17B, 35 μm gold tin foil punched out to a 0.7 mm square was put into the jig 170 one by one, and the gold-plated thermoelectric semiconductor elements 13 a and 13 b were made upright. Thereafter, a gold tin foil of the same size was placed on the gold plating surface on the upper surface side of the thermoelectric semiconductor elements 13a and 13b, and further heat fusion was performed in a reducing atmosphere as shown in FIG. The fusing conditions were performed in a reducing atmosphere at 320 ° C. and held for 1 minute.

  As described above, when the gold-tin foil is fused in the element state after being shredded as the thermoelectric semiconductor elements 13a and 13b, the amount of gold-tin per element can be strictly controlled, but the gold formed on the element As shown in FIG. 17 (d), the tin layer was in a state close to a spherical surface as if the bowl was turned down by surface tension.

  However, since this shape does not cause a problem in assembling, the thermoelectric semiconductor elements 13a and 13b and the pair of ceramic substrates 11 and 12 having 31 pairs of land portions are processed in the same manner as described in the third embodiment. Was used to assemble the gold-tin bonded thermomodule 10.

  In addition, when the assembled thermo-module 10 was destroyed and the joining state of the gold tin was inspected, the amount of gold tin was controlled, so that the spread of gold tin between the patterns (land portions) was uniform. Results were obtained.

  After attaching the lead wire 15 to the thermo module 10 assembled by the above method, the internal resistance (R1) is measured, and then the thermal shock test at -40 ° C / 85 ° C (30 minutes / cycle, 20 cycles) And a reverse energization test (current application, switching for 7.5 seconds, 72 cycles so that the temperature reached 70 to 75 ° C. on the cooling side / heat radiation side) was performed.

  As a result of measuring the internal resistance (R2) after this test and determining the rate of change in resistance, it was confirmed that all the thermo modules 10 increased by about 0.5% and functioned satisfactorily as the thermo module 10.

  From the above, after the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b are shredded, a gold-tin layer is provided on the outermost surface, and the gold-tin junction thermomodule 10 is assembled using these elements 13a, 13b. The effectiveness was confirmed.

Example 9
In the present embodiment, a P-type thermoelectric semiconductor element 13a and an N-type thermoelectric semiconductor element 13b having different nickel plating thicknesses are produced through the steps shown in FIG. 18, and then a module is assembled using these elements 13a and 13b. A thermal test was attempted.

  First, each ingot 70 (refer FIG. 2) is produced, heating and pressurizing the P-type and N-type thermoelectric semiconductor powder which has bismuth-tellurium as a main component, and each ingot 70 is sliced, P-type thermoelectric semiconductor A wafer 71 and an N-type thermoelectric semiconductor wafer 71 were obtained. A wafer size of approximately 30 mm × 40 mm and a thickness of approximately 0.8 mm were prepared depending on the module performance.

  Next, the P-type thermoelectric semiconductor wafer 71 and the N-type thermoelectric semiconductor wafer 71 were each etched with a mixed acid of inorganic acid, and then nickel-plated.

  Here, a standard electroless nickel plating level as a standard, and an electrolytic nickel plating level used for decoration were deposited approximately 4 μm. Gold plating was applied to these nickel platings at 0.2 to 0.3 μm to prepare gold-plated wafers.

  Next, both surfaces of each gold-plated wafer are fused with a 35 μm-thick gold tin foil (foil) using a vacuum furnace, and then diced into 0.64 mm × 0.64 mm squares to obtain P-type thermoelectric semiconductor elements 13a and N-type thermoelectric elements. A semiconductor element 13b was obtained and assembled into a gold-tin bonded thermomodule 10 having 23 element pairs using these elements 13a and 13b.

  Thereafter, a thermal shock test and an inversion energization test were performed on the thermo module, and then a copper tungsten (20%) plate having a thickness of 1 mm was bonded to both surfaces of the thermo module 10 using tin silver copper solder.

  As a result of evaluating the endurance of the sample module thus created by reverse energization (applying current so that the temperature of the heat dissipation side substrate and the temperature of the cooling side substrate go back and forth between 25 ° C. and 85 ° C.) The change in resistance value after the cycle was less than 5% of the pass / fail judgment regardless of the type of nickel plating.

  For comparison, in this example, a sample in which 0.2 to 0.3 μm of gold plating was applied immediately after etching of the wafer 71 was made as a prototype.

  As with other nickel-plated wafers, 35 μm thick gold-tin foil was fused on both sides of this sample and diced into thermoelectric semiconductor elements 13a and 13b, and then these elements 13a and 13b were used. A sample module having 23 element pairs was prepared.

  The durability of this sample module was evaluated after joining the copper-tungsten plate in the same manner as the other modules 10, but each sample module had a very short cycle number and the resistance value change exceeded 5%. . These are considered to have exfoliated at the interface between the Bi-Te base material and the gold-tin layer, thereby increasing the resistance value.

Example 10
In this example, a P-type thermoelectric semiconductor wafer 71 and an N-type thermoelectric semiconductor wafer 71 in which a gold-tin foil was thermally fused were produced by the same method as in Example 3 (see FIG. 8).

  However, in this example, the gold-tin fused wafer 71 was prepared by changing the etching chemicals and the processing time of the base. As a result, crater-like wrinkles such as shown in FIG. 19 were generated on the surface of the gold tin wafer depending on the etching conditions.

  When dicing the gold-tin fused wafer 71 in which such crater-like wrinkles are generated, peeling frequently occurs at the bismuth-tellurium base material and the nickel interface at the wrinkled locations, so that the base material is locally / It is inferred that the adhesion at the nickel interface is weak.

  In order to quantitatively grasp the magnitude of this adhesion, a nickel / gold plated wafer with the same etching conditions is diced into 3 mm squares, one side of which is soldered to a 2 mm thick copper plate with tin antimony solder, A tin-plated copper nail was soldered using lead tin solder.

  Using the sample thus prepared, it was pulled vertically at a constant speed of 20 mm / min, and the breaking strength was evaluated as the adhesion. As a result, it was found that the crater-like wrinkles occur when the adhesion per square centimeter is less than 50 kg. On the other hand, it was found that an adhesion force of 50 kg or more per square centimeter is necessary so that wrinkles on the crater do not occur.

  Furthermore, in this example, based on the above experimental results, for example, according to the procedure shown in FIG. 20, from the P-type and N-type thermoelectric semiconductor wafers 71, a sample with an adhesion force F of about 40 kg per square meter, a sample of about 50 kg, A sample of approximately 80 kg and a sample of approximately 100 kg are prepared, and a gold tin foil is thermally fused to each sample (wafer) and further diced into thermoelectric semiconductor elements 13a and 13b, and then these elements 13a and 13b are used. Thus, a gold-tin bonded thermo module 10 was prepared.

  In addition, as described above, crater-like wrinkles were generated in the sample having an adhesion force per square meter of less than 50 kg, and peeling occurred frequently during dicing. However, samples without peeling were selected and used for assembly.

  As a result of subjecting each thermomodule assembled using the above four levels of samples to a thermal shock test (100 cycles) in which minus 40 ° C. and 85 ° C. are applied at intervals of 15 minutes, the amount of change in the internal resistance value before and after the test is The thermo module with an adhesion strength of 40 kg was clearly larger than the thermo module with an adhesion strength of 80 kg or more.

  Here, when a product with a change rate of 2% is judged as a defective product, there is a clear correlation between the defective rate and the adhesion force, and a thermo module with an adhesion force of 80 kg or more per square centimeter has a defect rate of 0. Compared to the percentage (0/50), the 40kg adhesion thermo module had a defective rate of 18% (9/50). In addition, the thermo module with a 50 kg adhesion force had a defective rate of 4 (2/50) percent.

  From the above, in the gold-tin bonded thermomodule 10, it is practically necessary that the adhesion between the P-type thermoelectric semiconductor and the N-type thermoelectric semiconductor and the nickel interface be 50 kg or more, preferably 80 kg or more per square centimeter. It could be confirmed.

Example 11
The same test as in Example 10 was also performed for the gold tin paste method. Specifically, a nickel / gold plated wafer having different adhesion between the bismuth-tellurium base material and the nickel interface was prepared by changing the etching conditions in the same manner as in Example 10, and gold tin was produced in the same manner as in Example 1. The joining thermo module 10 was created.

  Thereafter, the thermal shock test described in Example 10 was carried out to investigate the relationship between the adhesion force and the defect rate. In this case as well, as in Example 10, the defect rate is high when the adhesion force is less than 50 kg, which is practical. It became clear that it was not.

Example 12
In the present embodiment, a gold tin layer is formed on the land portions (metallized layers) 111 and 121 of the ceramic substrates 11 and 12 by the procedure shown in FIG. 21, and the gold tin is formed using the thermoelectric semiconductor elements 13a and 13b having only a gold plating finish. The joining thermo module 10 was assembled.

  In this embodiment, the gold tin layer is formed on the substrate metallized surface by applying a predetermined amount of a commercially available gold tin paste to the metallized surfaces (land portions 111 and 121) of the ceramic substrates 11 and 12 [FIG. Reference], followed by heating at 320 ° C. for 1 minute in a reducing atmosphere in a vacuum furnace (see FIG. 21B).

  The used ceramic substrates 11 and 12 are alumina-made 23-pair land holding substrates made by a semi-additive method, and the outer dimensions are approximately 6 mm × 8 mm.

  The thickness of the gold-tin layer was about 10 μm [see FIG.

  This process was further repeated twice to form an approximately 30 μm gold-tin layer on the land [see FIG. 21 (c)]. In addition, since the board | substrates 11 and 12 were created by the semi-additive method, most of the side walls of the land parts 111 and 121 were exposed, and gold tin did not flow into the side walls at the time of melting.

  Using the ceramic substrates 11 and 12 thus obtained and the gold-plated thermoelectric semiconductor elements 13a and 13b (for example, those generated by the method of FIG. 2), the gold-tin bonded thermomodule 10 was assembled [ See FIG. 21 (d)].

  The assembly method was performed by placing the substrate 11 at a predetermined position using an automatic machine and arranging the thermoelectric semiconductor elements 13a and 13b while applying a high-viscosity flux to the land portion 111 of the substrate 11.

  Immediately after the placement of the thermoelectric semiconductor elements 13a and 13b, heat bonding was performed at 350 ° C. for 12 seconds to obtain a π set state module. Thereafter, another substrate 12 is stacked on the π set state module and heated at 350 ° C. for 2 minutes, so that the thermoelectric semiconductor elements 13a and 13b and the substrates 11 and 12 are joined by the gold tin layers 113 and 123. The gold-tin bonded thermo module 10 was produced.

  The bonded state was confirmed by embedding in epoxy resin and polishing in both of these assembled states, but the re-melted gold tin was almost the same as the bonded state of the modules prepared in the other examples and exhibited a good bonded state. It was.

  After that, lead wire 15 is attached to thermo module 10, internal resistance (R1) is measured, and thermal shock test and reverse energization test (cooling side / heat dissipation side) at -40 ℃ / 85 ℃ (30 minutes / cycle, 20 cycles) The current was applied so that the temperature difference reached 70 to 75 ° C. was switched for 7.5 seconds and 72 cycles).

  As a result of measuring the internal resistance (R2) after the test and determining the rate of change in resistance, it was confirmed that all the thermo modules increased by about 0.5% and functioned sufficiently as the thermo module 10.

Example 13
Even in a conventional thermo module using lead-tin eutectic solder (melting point 183 ° C.) or tin antimony solder (melting point 232 ° C.), the substrate itself warps when the substrate size increases. The thermoelectric semiconductor element may be in a floating state without being bonded to one of the substrate metallization layers.

  In order to avoid such an assembly failure, the same solder as the thermoelectric semiconductor element is coated on the metallized surface of the substrate to reduce the assembly failure.

  When gold tin is used as the bonding agent, the same phenomenon is feared. Therefore, in this example, preliminary gold tin soldering was performed on the substrate-side metallized surface.

  That is, in this embodiment, the thermo module is assembled after the gold tin layer is formed on both the metallized layers (land portions) of the ceramic substrates 11 and 12 and the thermoelectric semiconductor elements 13a and 13b.

  FIG. 22 is a diagram showing a thermomodule assembly process in the present embodiment.

  As shown in FIG. 22, in the present embodiment, the gold tin spare solder on the substrate metallized surface is coated with a predetermined amount of a commercially available gold tin paste on the metallized layers (land portions 111, 121) of the ceramic substrates 11, 12. [Refer to FIG. 22 (a)], and then heated in a reducing atmosphere in a vacuum furnace at 320 ° C. for 1 minute (see FIG. 22 (b)).

  The ceramic substrates 11 and 12 used are 47-made land-apart substrates made of alumina, and the outer dimensions are approximately 6 mm × 14 mm. The thickness of the preliminary solder was about 10 μm from the cross-sectional observation.

  Ceramic substrates 11 and 12 having a spare hand obtained through the steps of FIGS. 22A and 22B, and a thermoelectric semiconductor element in which a gold tin layer is formed on the outermost surface obtained by, for example, the method shown in FIG. The module assembly was performed using 13a and 13b, and the gold tin joining thermomodule 10 with which the thermoelectric semiconductor elements 13a and 13b and the board | substrates 11 and 12 were joined by the gold tin layers 113 and 123 was obtained [FIG.22 (c). reference〕.

  The assembly of the gold-tin bonded thermomodule 10 in this example was performed in the same manner as in Example 3 except that preliminary soldering was performed on the ceramic substrates 11 and 12.

  For comparison, we prototyped a level (module) that does not carry out preliminary soldering, measured the internal resistance (R1) after attaching the lead wire, and calculated the rate of resistance change from the internal resistance (R2) after the thermal shock test and reverse current test. The ratio of non-defective products was determined (the rate of change was determined to be a non-defective product when the rate of change was below the reference value).

  As a result, the percentage of non-defective products was 100% when the pre-soldering of gold and tin was preliminarily soldered on the substrates 11 and 12, whereas the module prototyped without spare solder was 80%. These tendencies are often observed in thermo modules using tin antimony solder.

  From this, it has been clarified that defective bonding can be reduced by performing preliminary gold-tin solder on the ceramic substrates 11 and 12.

Example 14
In this example, as in Example 3, the bonding conditions were obtained in a vacuum furnace under a reducing atmosphere using alumina substrates 11 and 12 having 21 land portions and 35 μm-thick gold tin foil fusion thermoelectric semiconductor elements 13a and 13b. Was examined.

  In this case, the temperature in the vicinity of the bonding surface was measured by fixing a thermocouple to the back surface of the substrates 11 and 12 with heat-resistant tape.

  In addition to 280 ° C., which is the melting point of gold tin, the temperature measured in this way is 300 ° C., 320 ° C., 340 ° C., 5 seconds, 10 seconds, 20 seconds, 30 seconds, 1 minute, 3 minutes, As a result of bonding under a time condition of 5 minutes, it was confirmed that bonding was possible if heated to 280 ° C. or higher, which is the melting point, for 10 seconds or more. However, in order to realize a so-called “wet state” by flowing gold tin over the entire substrate metallization (land portion), a heating time of about 1 minute was required.

  In addition, the durability of the thermo module created under such temperature and time conditions is 7.5 so that the temperature difference between the cooling side substrate 12 and the heat radiating side substrate 11 becomes 80 ° C. As a result of evaluation in an accelerated test in which reversal energization was performed at intervals of seconds, no dependence on the junction temperature was observed, and all the thermo modules heated for 10 seconds or more showed durability of 20,000 cycles. However, the sample with a heating time of 5 seconds was not practical because the resistance of most modules increased after 2,000 cycles.

  From the above, it has been clarified that when gold tin is used for joining the ceramic substrates 11 and 12 and the thermoelectric semiconductor elements 13a and 13b, it is necessary to heat at least a temperature equal to or higher than the melting point for 10 seconds or more.

Example 15
In this example, the thermomodule was assembled by changing the thickness of the gold-tin layer fused to both surfaces of the thermoelectric semiconductor elements 13a and 13b from 20 μm to 50 μm.

  In the conventional lead tin solder or tin antimony solder, the thickness of the solder layer after bonding is 10 to 20 μm regardless of the solder amount of the thermoelectric semiconductor element. However, in the case of gold tin bonding, the thermoelectric semiconductor element 13a is used. , 13b is joined with almost no change in the thickness of the gold tin fused. In this example, a load greater than that of the conventional module was applied during bonding, and the thickness of the bonding layer was changed in the range of 5 μm to 50 μm.

  After the module was assembled, a 1 mm thick copper tungsten plate was joined to both ends of the thermo module with tin silver copper solder, and a thermal shock test was repeated in which a temperature cycle of −40 ° C. and 85 ° C. was repeated.

  It was confirmed that the rate of change in resistance after 100 cycles of the thermal shock test was within the practical range, with any joint thickness level (module) being less than 5 percent of the pass / fail judgment. Accordingly, the thickness of the gold-tin layer that was tested is considered to be an appropriate range for producing the durable gold-tin bonded thermomodule 10.

Example 16
In this example, in the test stage, after assembling the module, the power supply lead wire 15 was attached using a gold tin paste having a gold content in the solid content of approximately 80 weight percent.

  The gold-tin paste used is a commercial product, the flux type is RMA type, and the viscosity is about 200 Pa · s. As a specific method, a soldering hand was used to join the metallized layer of the substrate and the tinned copper wire in the air.

  Separately, φ0.3 tin-plated copper wire was joined to a plate with pure nickel plated on the outermost surface of pure nickel, and the peel strength was compared with the adhesion strength obtained by joining with tin antimony solder as a comparative sample. Comparison was made by (a tensile test of the lead wire 15 in the vertical direction with respect to the joint surface).

  All of the gold-tin joints showed a strength of 2 kgf or more, whereas in the case of the tin antimony solder joint, there was a sample in which f solder breakage occurred from 1 kgf to 1.5 kg. From this, it was confirmed that joining with gold tin was sufficient in terms of strength.

  Next, the lead wires 15 were attached to the 31-pair land-holding gold-tin bonded thermomodule 10 manufactured in the same manner as that manufactured in Example 3 using gold-tin paste.

  FIG. 23 is a conceptual diagram showing a lead wire attaching process in the present embodiment. As shown in FIG. 23, in this embodiment, the eutectic composition component ratio is set on the lead wire mounting lands 112 a-1 and 112 a-2 formed at the pattern surface end of the heat radiation side substrate 11 of the thermo module 10. A satisfactory gold-tin paste is disposed, and each of the pair of lead wires 15 is disposed thereon.

  The lead wire 15 used for the thermo module 10 was a tin-plated copper wire having a wire diameter of φ0.3 mm and was joined by soldering. The surface condition after joining was smooth, and pit-like holes called blowholes were not seen.

  The gold-tin bonded thermomodule 10 thus prepared was judged to be acceptable or rejected by a thermal shock test and a reverse current test, and it was confirmed that all 30 prototypes functioned as thermomodules.

  In addition, a 1 mm thick copper tungsten plate was attached to the gold-tin bonded thermo module 10 with tin, silver and copper solder, and the durability by reversal energization was evaluated. However, even after the number of cycles normally required for a thermo module for optical communication, No change was observed in the lead part joined with tin.

Example 17
In this embodiment, the lead wire is joined to the thermo module after assembly using gold tin pellets.

  In the test stage, first, a gold-plated finish was applied to a pure nickel plate, and an attempt was made to join a tin-plated copper wire having a diameter of 0.3 mm by using a gold-tin pellet obtained by punching a gold tin foil having a thickness of 50 μm into a diameter of 1 mm.

  It was confirmed that there was sufficient bonding strength in both cases, whether melt-bonded in a reducing atmosphere in a vacuum furnace or melt-bonded in air using a soldering hand.

  Next, the lead wire 15 was attached to the gold-tin bonded thermomodule 10 owned by the 31-land portion manufactured in the same manner as in Example 3 using gold-tin pellets.

  The lead wire 15 used here was a tin-plated copper wire having a wire diameter of φ0.3 mm, and was joined in the air using a soldering hand. The surface condition after joining was smooth and there were no pits.

  The gold / tin bonded lead-attached thermo module 10 thus made was judged to be acceptable by a thermal shock test and a reverse current test, and it was confirmed that all 30 prototypes functioned as thermo modules.

Example 18
In this embodiment, a nickel post is used instead of the lead wire 15 used in the embodiment 17 to join the post-assembly position of the gold-tin bonding thermomodule 10 after assembly.

  The nickel post is obtained by applying gold plating to the outer peripheral portion of a nickel plate and then cutting it into approximately 1 mm square. In recent years, the nickel post is frequently used in place of the lead wire 15 in the optical communication field.

  In the experiment, a gold-tin paste was applied to the post mounting position of the assembled thermomodule 10 and a nickel post was placed thereon and joined in a vacuum furnace at 350 ° C. for 1 minute. The specific joining procedure is the same as in Example 19 described later.

  Compared to the case of tin antimony solder joint that is used normally, the bending strength after joining was confirmed to be more than twice as strong, and the effectiveness of using gold tin for post joining was confirmed. .

Example 19
As a lead member for power supply in the thermo module, a metal square column (post) having a size of approximately 1 mm square and 2 mm height may be used instead of the lead wire 15 used in the seventeenth embodiment.

  In this embodiment, gold tin is used for joining the metal post and the metallized layer (land portion) on the substrate.

  In particular, in this embodiment, after assembling the thermo module 10 in which the bonding between the substrates 11 and 12 and the thermoelectric semiconductor elements 13a and 13b is performed with gold tin, which has been described in each of the above-described embodiments, the gold-tin bonding thermostat is assembled. A metal post for power supply was attached to the module 10 using a gold tin paste having a gold content in the solid content of approximately 80 weight percent.

  The gold-tin paste used is a commercial product, the flux type is RMA type, and the viscosity is about 200 Pa · s.

  The joining was performed by the procedure as shown in FIG. 24, for example. First, the gold tin paste is applied to the post mounting positions (post mounting land portions 112b-1 and 112b-2) provided on the ceramic substrate 11 of the thermo module 10 after assembly [see FIG. 24 (a). Next, a pair of nickel posts 16 plated with gold are respectively mounted on the gold-tin paste (see FIG. 24B), and then pressed with a jig for preventing misalignment at 350 ° C. in a vacuum furnace. Post bonding was performed under heating conditions of 1 minute [see FIG. 24 (c)].

  In this post-bonding process, it was not possible to confirm whether or not the gold-tin layers 113 and 123 used for bonding the thermoelectric semiconductor elements 13a and 13b and the ceramic substrates 11 and 12 were remelted. There wasn't.

  After joining, a tin-plated copper wire of φ0.3 was attached to the upper surface of the post 16 with a gold-tin paste, a thermal shock and a reverse current test were performed, and a temperature difference between the heat radiation side substrate 11 and the cooling side substrate 12 was measured. It was confirmed that a temperature difference of 70 ° C. was generated.

  Accordingly, it is possible to join the power supply post using the gold-tin paste, and it is possible to produce the gold-tin joining thermomodule 10 using eutectic gold tin as the assembling solder.

Example 20
In this example, the metal post is bonded to the thermo module using gold tin pellets of φ1.2 mm and a thickness of 50 μm instead of the gold tin paste used in Examples 18 and 19.

  Specifically, the gold-tin bonded thermomodule 10 assembled using the alumina substrates 11 and 12 having the land portion 23 and the gold-tin fusion thermoelectric semiconductor elements 13a and 13b described in the fifth embodiment is prepared. A nickel post (1 mm square) with a gold plating finish and a height of 2 mm was joined to the post mounting position using a gold tin pellet with a diameter of φ1.2 mm and a thickness of 50 μm.

  The joining conditions were heating at 350 ° C. for 1 minute in a vacuum furnace, and an aluminum jig for preventing displacement was used for joining.

  After joining a nickel post, a tin plated copper wire of φ0.3mm was attached to the upper surface of the post with gold tin paste, the internal resistance (R1) was measured, and then -40 ° C / 85 ° C (30 minutes / cycle, 20 cycles) ) Thermal shock test and reverse energization test (current was applied so that the temperature difference between the cooling side and the heat release side was 70 to 75 ° C., switching for 7.5 seconds, 72 cycles).

  As a result of measuring the internal resistance (R2) after the test and determining the resistance change rate, it was confirmed that all the thermo modules had an internal resistance change rate of about 0.5% and functioned sufficiently as a thermo module.

Example 21
In this embodiment, a metal post is bonded in advance to the metallized layer forming substrate (heat dissipation side substrate 11) before assembling the thermoelectric semiconductor elements 13a and 13b with gold-tin paste, and then the substrate 11 to which the post is bonded Thermoelectric semiconductor elements 13a and 13b are joined to one substrate 12 (cooling side substrate) to assemble a thermo module.

  The substrate 11 used in this example is an alumina substrate having 23 land portions, and has 23 patterns (land portions 111) for mounting the P-type thermoelectric semiconductor elements 13a and N-type thermoelectric semiconductor elements 13b. Post mounting patterns (post mounting land portions 112b-1 and 112b-2) are metallized in two places.

  The other ceramic substrate 12 does not have the post-mounting pattern, and only the element mounting pattern (land portion 121) is formed at 23 locations.

  The material of the post is pure nickel, the size is 1mm square and the height is 1.8mm, and both sides of the 1mm square have a gold plating finish of 0.25 to 0.35μm.

  The post-joining and module assembling steps in this example were performed according to the procedure shown in FIG. 25, for example.

  First, a gold tin paste is applied to post mounting positions (post mounting land portions 112b-1 and 112b-2) provided on the heat radiation side ceramic substrate 11 before assembling as a module [see FIG. 25 (a)]. Next, a pair of nickel posts 16 that have been subjected to gold plating as described above are placed on the gold-tin paste, and are further pressed by a misalignment prevention jig in a vacuum furnace under heating conditions of 350 ° C. for 1 minute. Post bonding was performed [see FIG. 25 (b)].

  Thereafter, the thermoelectric semiconductor elements 13a and 13b and the cooling side substrate 12 were attached in a state where the nickel post 16 was attached to the heat radiation side substrate 11, and the module assembly was performed.

  Specifically, a P-type thermoelectric semiconductor element 13a and an N-type having a high viscosity flux applied to the land portion 11 of the heat radiation side substrate 11 on which the nickel post 16 stands and having a tin antimony solder layer on both surfaces thereon. Thermoelectric semiconductors were arranged and heat-bonded in this state to generate a π set state module [see FIG. 25 (c)].

  In the joining in the π group state module generation stage, the heat source set temperature was 320 ° C. and the heating time was 12 seconds. Usually, since the temperature of the joint surface is approximately 50 ° C. lower than the heat source temperature, the nickel post 16 previously attached did not cause a positional shift.

  Next, after cleaning the substrate 11 of the obtained π set state module, the heat dissipation side substrate 12 is overlaid so that the land portion 121 is aligned with the corresponding pair of thermoelectric semiconductor elements 13a and 13b, and then 320 ° C. Then, heat bonding was performed under a heating condition of 18 seconds (see FIG. 25D).

  In the example of FIG. 25, after the nickel post 16 is attached to the heat dissipation side substrate 11, the thermoelectric semiconductor elements 13 a and 13 b are attached on the heat dissipation side substrate 11 to form a π set state module, and then the cooling side substrate 12. Although the gold-tin bonded thermo module 10 is completed by attaching the post, the nickel post 16 is attached to the heat dissipation side substrate 11 and then the cooling plate 12 on which the post 16 does not stand. After the thermoelectric half elements 13a and 13b are attached to form a π set state module, the π set state module is combined with the heat radiation side substrate 11 on which the post 16 stands to complete the gold-tin bonded thermo module 10. There is also a good way.

  FIG. 26 is a diagram showing a post joining and module assembling process procedure based on this another method.

  In this case, after the nickel post 16 is attached to the heat radiation side substrate 11 in the same manner as in FIGS. 25A and 25B [see FIGS. 26A and 26B], the nickel post 16 is standing. P-type thermoelectric semiconductor elements 13a and N-type thermoelectric semiconductors 13b having a tin antimony solder layer on both surfaces are arranged on the land portion 121 of the cooling side substrate 12 that is not present, and heated in this state. The π pair state module was generated by joining [see FIG. 26 (c)].

  Next, the substrate 12 of the π set state module is inverted, and a pair of thermoelectric semiconductor elements 13a and 13b attached to the land portion 121 is applied to each pair of land portions 111 of the heat radiation side substrate 11 (a high viscosity flux is applied in advance). The substrate 12 was overlaid on the heat radiation side substrate 11 so as to be aligned with each other, and then heat bonded (see FIG. 26D).

  After attaching a tin-plated copper wire of φ0.3 to the nickel post 16 of the gold-tin bonded thermomodule 10 obtained through the process of FIG. 25 or FIG. 26 with tin antimony solder, the internal resistance (R1) was measured, -40 ° C / 85 ° C (30 minutes / cycle, 20 cycles) thermal shock test and reverse energization test (applying current so that the temperature difference between the cooling side / heat radiation side is 70 to 75 ° C, switching for 7.5 seconds, 72 cycles).

  As a result of measuring the internal resistance (R2) after the test and obtaining the rate of change in resistance, it was confirmed that all the thermo modules 10 increased by about 0.5% and functioned satisfactorily as thermo modules.

  The solder used for module assembly in this example was tin antimony solder (melting point 232 ° C.) having a melting point lower than that of gold tin. Normally, when the same kind of solder is used, the elements 13a and 13b cannot be assembled after the post 16 is attached. However, in this embodiment, the gold tin used for joining the post 16 is more than tin antimony solder. Since the melting point is much higher, it was possible to assemble the post 16 attached earlier without causing a positional shift, and the effectiveness of this method was confirmed.

  From each Example described above, the effectiveness of joining the ceramic substrate 11 and the post 16 with a gold tin layer could be confirmed.

  Next, the utilization form of the gold tin joining thermomodule 10 of this invention is demonstrated.

  One of the uses of the gold-tin bonded thermo module 10 of the present invention is precise temperature control of a laser diode of an optical communication module.

  FIG. 27 is a diagram showing a conceptual cross-sectional configuration of an optical communication module 100 in which the gold-tin bonding thermomodule 10 of the present invention is mounted.

  In this optical communication module 100, a gold-tin bonded thermomodule 10 manufactured based on the research results in the above embodiments is mounted in a package 60.

  Specifically, the package 60 is mounted so that the non-patterned surface of the heat-dissipation-side ceramic substrate 11 of the gold-tin bonded thermomodule 10 comes into contact with the inner bottom surface of the package 60. Further, in this state, the light source of the optical communication module 100 is placed on the non-pattern surface of the cooling-side ceramic substrate 12 of the gold-tin bonded thermomodule 10 via a heat spreader 20 made of, for example, CuW (copper-tungsten alloy). A laser diode 30 is arranged.

  The laser diode 30 receives power from a control unit (not shown) and generates laser light modulated by predetermined transmission data. The laser light is guided to the optical fiber 40 and transmitted through the optical fiber 40 toward a predetermined receiving circuit.

  A thermistor 50 is provided on the heat spreader 20. The control unit variably controls the cooling temperature of the cooling-side substrate 12 by controlling the power supply to the gold-tin bonded thermo module 10 based on the temperature detected by the thermistor 50. As a result, the laser diode 30 is controlled to the target temperature and always maintains an appropriate oscillation frequency.

  When assembling the optical communication module 100 according to the present invention, the heat spreader 20 and the cooling-side ceramic substrate 12 of the gold-tin bonded thermomodule 10 and the laser diode 30 are bonded by, for example, tin antimony solder.

  Here, the melting point temperature (232 ° C.) of the tin antimony solder is the melting point temperature (280 ° C.) of the gold tin layer used for bonding between the ceramic substrates 11 and 12 and the thermoelectric semiconductor elements 13 a and 13 b of the gold tin bonding thermomodule 10. Much lower than

  In other words, in the optical communication module 100 according to the present invention, the gold-tin bonded thermo module 10 can be incorporated and mounted in the package 60 without causing an influence such as melting on the gold-tin layer of the thermo module 10.

  Further, according to the optical communication module 100 according to the present invention, a gold-tin bonding thermostat is used without using a tin-tin eutectic solder (melting point 183 ° C.) but using a tin antimony solder (melting point 232 ° C.) having a higher melting point. Since the module 10 can be incorporated and the thermomodule 10 itself uses a bonding agent (gold tin) that does not contain a lead component as described above, lead-free as viewed from the entire optical communication module 100 is also possible. I can do it.

  Further, the gold-tin bonded thermomodule 10 mounted on the optical communication module 100 has a high Young's modulus between the P-type thermoelectric semiconductor element 13a and the N-type thermoelectric semiconductor element 13b and the ceramic substrates 11 and 12, and has good creep resistance. Since the structure is joined by the tin layer, the ceramic substrates 11 and 12 need not be deformed even when a thermal change occurs.

  Thereby, in particular, it is possible to suppress the deformation accompanying the thermal change of the cooling-side ceramic substrate 12 on which the laser diode 30 is mounted, and to reduce the influence of the deformation on the attitude change of the laser diode 30. The optical axis shift of the laser diode 30 with respect to the change can be greatly reduced.

  As described above, the gold-tin bonded thermomodule 10 according to the present invention has a structure in which the P-type and N-type thermoelectric semiconductor elements and the ceramic substrate are bonded with the gold-tin layer, thereby making the lead-free and optical communication module 100 possible. This contributes to two aspects of stabilizing the optical axis of the laser diode when used for precise temperature control of the laser diode 30.

  The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within a range not changing the gist thereof.

  For example, in the above embodiment, the gold-tin bonding structure based on the thermo module used for precise temperature control of the laser diode 30 of the optical communication module 100 has been described. However, the gold-tin bonding structure of the present invention is a thermo module for other uses. It is also applicable to.

As described above, according to the present invention, the P-type and N-type thermoelectric semiconductor elements and the ceramic substrate are bonded using a gold-tin eutectic composition bonding agent having a gold content of approximately 80 weight percent. Therefore, even when the gold-tin bonded Peltier element thermoelectric exchange module is used for precise temperature control of a laser diode of an optical communication module, for example, solder having a melting point lower than that of the gold tin layer and higher than that of the lead tin solder The thermoelectric conversion module can be joined to a laser diode or the like, and the thermoelectric conversion module can be reliably incorporated into the optical communication module, and lead-free as viewed from the entire optical communication module can be realized.

  In addition, the gold-tin bonded Peltier element thermoelectric conversion module incorporated in the optical communication module has a higher Young's modulus than lead-tin solder, and has a strong bonded structure using a gold-tin layer with good creep resistance, which makes it a ceramic against temperature changes. The deformation of the substrate is small, and it is possible to contribute to prevention of optical axis shift of the laser diode with respect to temperature change while suppressing the influence on the posture deformation of the laser diode bonded to the thermoelectric conversion module.

  DESCRIPTION OF SYMBOLS 10 ... Gold-tin junction Peltier element thermoelectric conversion module (thermo module), 11 ... Ceramic substrate (heat radiation side), 111 ... Land part (metallized layer), 1111 ... Copper metallized layer, 1112 ... Nickel metallized layer, 1113 ... Gold plating, 112a -1, 112a-2 ... lead wire mounting land, 112b-1, 112b-2 ... post mounting land, 113 ... gold tin layer, 114 ... back metallization layer, 1141 ... copper metallization layer, 1142 ... nickel metallization layer, DESCRIPTION OF SYMBOLS 1143 ... Gold plating, 12 ... Ceramic substrate (cooling side), 121 ... Land part (metallized layer), 123 ... Gold tin layer, 124 ... Back metallized layer, 15 ... Lead wire, 16 ... Metal post, 70 ... Ingot, 71 ... P / N type thermoelectric semiconductor wafers, 170 ... carbon jigs, 171 ... Over DOO, 172 ... reamed holes, 100 ... optical communication module, 20 ... heat spreader over, 30 ... laser diode, 40 ... optical fiber, 50 ... thermistor, 60 ... Package

Claims (4)

A plurality of P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, a pair of ceramic substrates joined to upper and lower sides of the P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, and a lead member provided on one of the ceramic substrates The main component has a metal post for power supply joined to the metallization layer for mounting,
A gold-tin eutectic composition gold containing approximately 80 weight percent of gold that does not contain a lead component and has a higher Young's modulus than lead tin on both upper and lower sides of each thermoelectric semiconductor element. A thermoelectric conversion module is assembled by joining with tin,
The metal post is gold plated on the outer periphery of a nickel plate,
Gold-tin containing approximately 80 weight percent of gold that does not contain a lead component and has a higher Young's modulus than lead-tin in the joining of the metal post and the metallization layer for mounting the lead member of the one ceramic substrate A Peltier element thermoelectric conversion module using eutectic gold tin. A plurality of P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, a pair of ceramic substrates joined to upper and lower sides of the P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, and a lead member provided on one of the ceramic substrates The main component has a metal post for power supply joined to the metallization layer for mounting,
Gold-tin containing approximately 80 weight percent of gold that does not contain a lead component and has a higher Young's modulus than lead-tin in the joining of the metal post and the metallization layer for mounting the lead member of the one ceramic substrate In the manufacturing method of Peltier element thermoelectric conversion module using gold tin of eutectic composition,
After assembling the thermoelectric conversion module by bonding the pair of ceramic substrates to the upper and lower sides of each thermoelectric semiconductor element using the gold tin , the metal post and the metal member for mounting the lead member on the one ceramic substrate A method for manufacturing a Peltier element thermoelectric conversion module, characterized in that bonding to a layer is performed. The gold-tin alloy layer having the gold-tin eutectic composition is electrolytically deposited on the joint surface of the metal post, and the alloy layer is used to form the metal post and the metallization layer for attaching the lead member of the one ceramic substrate. The method of manufacturing a Peltier element thermoelectric conversion module according to claim 2 , wherein bonding is performed. A plurality of P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, a pair of ceramic substrates joined to upper and lower sides of the P-type thermoelectric semiconductor elements and N-type thermoelectric semiconductor elements, and a lead member provided on one of the ceramic substrates The main component has a metal post for power supply joined to the metallization layer for mounting,
The bonding between the upper and lower sides of each thermoelectric semiconductor element and the pair of ceramic substrates and the bonding between the metal post and the metallization layer for attaching the lead member of the one ceramic substrate do not contain a lead component and are more than lead tin. A Peltier element thermoelectric conversion module using gold-tin eutectic composition containing approximately 80% by weight of gold with a high Young's modulus;
A laser diode controlled to a target temperature by the Peltier element thermoelectric conversion module;
With the inside of the package,
The optical communication module, wherein the laser diode is attached to the Peltier element thermoelectric conversion module through solder not containing lead and having a melting point lower than that of gold tin.

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