JP2007209989A - High-temperature brazing filler metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-temperature brazing filler metal composed of a Zn based solder alloy combining satisfactory wettability and plastic workability. <P>SOLUTION: The Zn based solder alloy comprises at least one selected from the group consisting of, by mass, 0.1 to 1% Al, 0.05 to 1% Ge, 0.01 to 1.0% V and 0.01 to 0.5% P, and the balance Zn with inevitable impurities. In a semiconductor device, an adhesive part is obtained by using the high-temperature brazing filler metal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high temperature brazing material for high temperature soldering in the assembly of electronic parts and mechanical parts, and more particularly to a high temperature brazing material made of a Zn-based solder alloy.

  Soldering in the assembly process of various electronic components including die bonding of power transistor elements is performed by high-temperature soldering, and a relatively high-temperature solder alloy having a melting point of about 300 ° C. (hereinafter referred to as a high-melting-point solder alloy) Is used as a high-temperature brazing material. As a high temperature brazing material, an alloy represented by a Pb-5 mass% Sn alloy (Pb solder alloy) and an Au-20 mass% Sn alloy have been conventionally used.

  However, in recent years, due to consideration for environmental pollution, there has been a strong movement to limit the use of Pb, and in response to such movement, in the field of electronic component assembly, a high melting point solder alloy containing no Pb is required. Yes. Further, since a high melting point solder alloy containing Au is expensive, a high melting point solder alloy not containing Au is required.

  As described above, Zn-Al-Ge alloys and Zn-Al-Ge-Mg alloys are described in JP-A-2000-208533 as high melting point solder alloys that do not contain Pb and do not contain Au. ing.

  However, although wettability with respect to Ag plating was obtained, it was not possible to join Cu or Ni due to insufficient wettability, and further, plastic workability was poor and expensive.

  Further, Zn-Al-Ge-P for the purpose of improving wettability is described in JP-A-2004-358540, and Zn-Al-Mg-Ga-P is disclosed in JP-A-2004-358539. However, in the inventions described in these publications, although wettability is improved, plastic workability is poor and expensive.

JP 2000-208533 A

JP 2004-358540 A

JP 2004-358539 A

  In view of such circumstances, an object of the present invention is to provide a high-temperature brazing material made of a Zn-based solder alloy having both good wettability and plastic workability.

  The high temperature brazing filler metal of the present invention comprises 0.1% by mass to 1% by mass of Al, 0.05% by mass to 1% by mass of Ge, 0.01% by mass to 1.0% by mass of V, and It contains at least one selected from the group consisting of 01% by mass to 0.5% by mass P, with the balance being Zn and inevitable impurities.

  In the semiconductor device of the present invention, the bonding portion is obtained using the high-temperature brazing material.

  The high-temperature brazing material of the present invention is made of a Zn-based solder alloy that does not contain Pb and does not contain Au, has both good wettability and plastic workability, and can be produced at low cost. Widely applicable in assembly. As a result, an environment-friendly semiconductor device can be provided by not including Pb.

  The high temperature brazing material of the present invention is based on Zn having a melting point of 420 ° C., and by adding at least one selected from the group consisting of Al, Ge, V and P, not only Ag but also Cu and Ni. However, it also has good plastic workability while ensuring good wettability.

  The high-temperature brazing material of the present invention has a lower amount of Al and Ge than the brazing material described in JP-A-2004-358540 and has no effect of lowering the melting point, but the bonding temperature is 420 ° C. or higher. Thus, good plastic workability can be obtained because of good bonding and a small amount of Al and Ge.

  Al, Ge, V, and P are all elements that improve wettability, and by adding these, good wettability can be secured not only for Ag but also for Cu and Ni. The present inventors presume that this can prevent oxygen from preferentially reacting with Al, Ge, V, or P and generating an oxide film on the surface of the solution during melting of the brazing filler metal.

  When adding Al, the content of Al is 0.1% by mass to 1% by mass. If it is less than 0.1% by mass, it is difficult to ensure good wettability, and the probability of occurrence of poor bonding at the time of bonding becomes high. It is difficult to ensure good wettability. In addition, the hardness of the obtained Zn-based solder alloy increases, and the plastic workability decreases.

  When adding Ge, content of Ge shall be 0.01 mass%-1.0 mass%. If it is less than 0.01% by mass, it is difficult to ensure good wettability and the probability of occurrence of poor bonding during bonding becomes high. If it exceeds 1.0% by mass, a large amount of Ge oxide film is produced during bonding. As a result, good wettability cannot be ensured. In addition, the hardness of the obtained Zn-based solder alloy increases, and the plastic workability decreases.

  When V is added, the content of V is set to 0.01% by mass to 1.0% by mass. If it is less than 0.01% by mass, it is difficult to ensure good wettability and the probability of occurrence of poor bonding during bonding becomes high. If it exceeds 1.0% by mass, a large amount of Ge oxide film is produced during bonding. However, it is difficult to ensure good wettability. In addition, the hardness of the obtained Zn-based solder alloy increases, and the plastic workability decreases.

  When adding P, content of P shall be 0.01 mass%-0.5 mass%. If it is less than 0.01% by mass, it is difficult to ensure good wettability, and the probability of occurrence of poor bonding at the time of joining becomes high. Addition exceeding 0.5% by mass is incorporated in the obtained Zn-based solder alloy. P does not melt, making manufacture difficult.

[Examples 1 to 22, Comparative Examples 1 to 8]
A high-temperature brazing material was melted in an atmospheric melting furnace using Zn ingot, Al ingot, metal Ge, metal V, and metal P (all of the above materials had a purity of 99.9% by mass).

  The composition of the obtained high temperature brazing material was measured by chemical analysis. The analysis results are shown in Table 1.

  Furthermore, the obtained high temperature brazing material was evaluated for wettability as follows.

(1) A brazing material bath that is maintained in a nitrogen stream at 420 ° C. is prepared.

(2) The copper piece and the Ni-plated copper piece are immersed in the brazing material bath prepared in (1) for 5 seconds, and then taken out and observed.

(3) On each of the copper surface and the Ni plating surface, when the brazing material spreads wet, it was evaluated as “good”, and when it did not spread, it was evaluated as “bad”. The evaluation results are shown in Table 1.

  As evaluation of plastic workability, the obtained high-temperature brazing material was cut into a plate shape having a width of 10 mm, a thickness of 10 mm, and a length of 50 mm, and rolled to a thickness of 0.1 mm by cold rolling. The case where the plate was not cut to 0.1 mm was evaluated as “good”, and the case where a crack occurred during rolling or the plate was cut was evaluated as “bad”. The evaluation results are shown in Table 1.

  As shown in Table 1, the high temperature brazing material obtained in Comparative Examples 1 to 8 has poor wettability to the Ni plating surface, and the high temperature brazing material obtained in Comparative Examples 1, 5, 7, and 8. The wettability to the copper surface was also poor.

  Moreover, the high temperature brazing material obtained in Examples 1 to 22 has good wettability with respect to Cu and Ni, and has good plastic workability, and high temperature soldering in the assembly of electronic parts and mechanical parts. It can be seen that it is suitable for a wide range of applications.

Claims (2)

  0.1 wt% to 1 wt% Al, 0.05 wt% to 1 wt% Ge, 0.01 wt% to 1.0 wt% V, and 0.01 wt% to 0.5 wt% A high-temperature brazing material containing at least one selected from the group consisting of% P, with the balance being Zn and inevitable impurities.   A semiconductor device, wherein the bonding portion is obtained using the high-temperature brazing material according to claim 1.