JPH03204193A - Solder material - Google Patents

Abstract

PURPOSE:To improve the strength at the high temp. of a soldered part by dispersing and adding an intermetallic compd. which can constitute crystal nuclei at the time of solidification of a solder metal in and to the solder metal. CONSTITUTION:The finer crystal grains are formed and the formation of the coarser crystal grains at a high temp. is suppressed if the intermetallic compd. which can constitute the crystal nuclei at the time of solidification of he solder metal is dispersed and added in and to the solder metal. The strength at the high temp. is, therefore, improved. At least one kind of Cu6Sn5 and Ag3Sn can be adopted as the intermetallic compd. which can constitute the crystal nuclei. Further, at least one kind among Cu8Sn, Cu6Sn5, Ag3Sn, Ag3Sb, SnSb, In2Sn, InSn4, Ag2In, IgIn can be adopted. The amt. of the addition is preferably 0.02 to 8%, more particularly preferably 0.05 to 3% the entire part of the solder material. The high-temp. strength of the soldered part, for example, heat resis tance and cold and heat durability are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to solder materials. The solder material of the present invention can be applied to, for example, the soldering of automotive electronic equipment.

[Prior art] Conventionally, 5n63% by weight (hereinafter referred to as % by weight) has been used as a solder material.
A 5n-Pb alloy having a eutectic composition containing 37% Pb is known.

Since this solder material has a eutectic composition, it has a low melting point and is easy to solder join, and is widely used in electronic and electrical equipment.

However, when used in harsh environments, the conventionally used 5n-Pb alloys having a eutectic composition have insufficient strength in the soldered parts where the solder metal has solidified.

For example, when used in automotive electronic equipment, unlike other electronic equipment, it is used in high-temperature areas and undergoes repeated harsh cooling and heating cycles. Strength at high temperatures tends to be insufficient.

In addition, in recent years, JP-A-61-269998 has been used as a solder material.
As disclosed in the publication, Ag, s
It is known to contain B, have an oxygen content of 5 ppm or less, and have an average crystal grain size of 3 μm or less.

As another solder material, JP-A-60-166191
As disclosed in the publication, 3i is added to the 5n-Pb alloy.
, and those having excellent fatigue resistance properties with the addition of Cu are also known.

In addition, as other solder materials, as disclosed in Japanese Patent Application Laid-open No. 61-82994, B
There are also known materials with excellent fatigue resistance properties that include i and Aq.

[Problems to be Solved by the Invention] An object of the present invention is to provide a solder material that can increase the strength of a soldered part from a different perspective from conventional solder materials that have compositional characteristics as described above. shall be.

[Means for Solving the Problems] As a result of intensive research on solder materials, the present inventor has discovered that
If intermetallic compounds that can become crystal nuclei are dispersed in the solder metal when the solder metal solidifies, the solder metal solidified will increase the strength of the part, especially the strength at high temperatures (heat resistance, cold durability)
Based on this knowledge, we have completed the solder material of the present invention.

The reason why the above characteristics can be obtained by dispersing intermetallic compounds that can become crystal nuclei in the solder metal is that the intermetallic compounds contribute to the refinement of the crystal grains of the solder metal, so that the crystals of the solder metal after solidification are It is presumed that this is because the intermetallic compound suppresses the coarsening of grains at high temperatures.

The solder material of the present invention is characterized by comprising a solder metal and an intermetallic compound that is dispersed in the solder metal and can become crystal nuclei when the solder metal solidifies.

The solder material of the present invention may be in any form, including powder, rod, wire, plate, or foil. If the solder material is in powder form, the size of the powder particles can be selected as appropriate;
Further, when the solder material is rod-shaped, wire-shaped, plate-shaped, or foil-shaped, the diameter and thickness can be selected as appropriate.

Dispersion refers to the mixing of solder metal and intermetallic compound, and includes forms in which solder metal powder and intermetallic compound powder are mixed, and also forms in the form of powder particles, rods, and wires. This term also includes forms in which intermetallic compounds are mixed in the matrix structure of the solder metal, such as plate-like or foil-like structures. In the case of the former form, the particle size of the solder metal powder particles is, for example, 1 μTrL to 50 μm, and the particle size of the intermetallic compound powder particles is, for example, 0.5 μTrL to 30 μm.
It can be μm.

As for the composition of the solder metal, conventionally known compositions can be used, such as Sn and 5n-Pb.

It may contain Pb or, if necessary, In, Sb, ACI, or Bi. Specifically, the conventionally used 5n-Pb system, pb-A, l system, 3n-3i system, 5n
-Pb-Bi system and 5n-Pb-In system can be adopted. Note that the proportion of each metal element forming the solder metal can be appropriately set in consideration of fluidity, strength, etc.

An intermetallic compound is a compound in which two or more metal elements are combined in a predetermined integer ratio, and even compounds in which a portion is a semimetal element and interstitial nonmetallic compounds have a constant composition ratio and have properties similar to metals. Contains compounds with

Intermetallic compounds typically have higher melting points than the solder metal.

As intermetallic compounds, Cug Sns, Ag3S
At least one of n can be employed. Zarani, Cus
Sn, CLI6 Sns, AQ3Sr11Ag3Sb
, 5nSb, In2Sn, In5rl, AQ2In, I
At least one type of QIn can be employed.

The proportion of intermetallic compounds in the entire solder material can be selected as appropriate depending on the required strength, fluidity, etc., but if it is too small, the crystal grains of the solder metal will not be sufficiently refined and the desired strength will not be achieved. I can't do it. Moreover, if the amount is too large, it will adversely affect the fluidity of the solder metal and reduce the strength of the joint. Therefore, the intermetallic compound is 0.0% when the entire solder material is taken as 100%.
02-8%, especially 0.05-3%.

An example will be explained in which a 5n-Pb alloy is used as the solder metal. In this case, at least one of Sb and In can be added to improve the thermal fatigue properties of the solder metal, and Sn can be added to CLI as an intermetallic compound.
s, A (HSn).In this case, when the entire solder material is taken as 100%, Sb is 1 to 15%, In is 1% or more, and intermetallic compounds are 0.
．． It can be set at 0.05 to 2%. Here, 3b, in
The reason for setting Sn to 1% or more is that if it is less than 1%, the desired strength of the soldering part cannot be obtained, and if left at a high temperature, the Sn
This is because a brittle compound phase formed by the reaction between the conductor and the conductor of the substrate grows, resulting in a significant decrease in the strength of the soldered part. The reason why sb is set to 15% or less is because if it exceeds 15%, the melting point of the solder metal will rise, the fluidity will deteriorate, and electronic components will be damaged by heat during soldering.

In the solder material of the present invention, when soldering is performed, the intermetallic compound may be dispersed in the matrix structure of the solder metal without melting into the solidified solder metal, or the intermetallic compound may be dispersed in the matrix structure of the solder metal without melting into the solidified solder metal. It may be integrally melted into the metal.

[Example] Next, using the mixed powder solder materials of Examples 1 and 2, the solder materials and flux (polymerized rosin) were mixed to form a paste, which was then applied to substrates and electronic components (semiconductor parts). (component or capacitor), and in that state was heated in the air at 240 to 250° C. for 5 to 6 minutes to perform actual soldering, and the strength of the soldered portion was tested. In the test, an electro-hydraulic servo tensile testing machine was used as a testing machine to examine the tensile strength after being left at room temperature, the tensile strength after being left at 120°C for 30 days, and the tensile strength after being left at 150°C for 30 days. Ta.

The solder materials of the first example were 5n-Pb-3b solder powder (particle size 30 μm) and Cu6Sn5 powder (particle size 20 μm).
) is a uniformly mixed powder. The solder powder was manufactured by a spraying method using gas atomization. Also CU6Sr
The ls powder was similarly produced by gas atomization. The solder material of the first example is 5n58%, Pb36%, Sb5%, CugSns, when the whole solder material is taken as 100%.
1%, with a composition of unavoidable impurities.

The solder materials of the second example were 5n-Pb-I n-based solder powder (particle size 30 μm) and A03srl powder (particle size 15 μm).
It is in the form of a mixed powder that is uniformly mixed with m). AQa
Sn powder was produced by gas atomization in the same manner as in the first example. The solder material of the second embodiment has a total solder material of 100%
When expressed as %, 5n58%, Pb36%, In5%, A
Q3Sn: 1%, with a composition of unavoidable impurities.

As a comparative example, 5n63%, Pb, which has been used conventionally.
Powdered solder material with eutectic composition of 37% (particle size 3Qu)
Soldering was carried out in the same manner using 1.m, ), and the strength of the soldered portion was tested.

The test results are shown in Table 1. As is clear from Table 1,
The tensile strength after being left at room temperature is 5.5 Nff/in the first example.
mm2, 4 in the second embodiment. El/mm2, 4 in comparative example
．． 5Ng/mm2, which is almost unchanged. However, the tensile strength after being left at 120°C for 30 days, 1
The tensile strength after being left at 50°C for 30 days decreased to 1.9 kcl/mm2 in the case of the comparative example, which was a significant decrease in strength, but in the case of the first and second examples, it was 3k.
It has a tensile strength of q/mm2 or more, and there is little decrease in strength.

This shows that the solder materials of the first and second examples have excellent heat resistance.

(Left below) Next, using each of the solder materials of the first and second examples, a paste was prepared by mixing each solder material with 7lux (polymerized rosin), and a glass epoxy board and an electronic component ( (semiconductor parts, capacitors, etc.), and soldered in that state under the same conditions as described above. Then, using a thermal shock tester as a tester, -30℃ (30 minutes) to 80℃
A cold and heat durability test was conducted in which a cold and heat cycle (30 minutes) was repeated many times. The comparative example was also subjected to a cold and heat durability test in the same manner. In the cold and heat durability tests, the electronic components of the first and second examples exhibited excellent cold and heat durability without malfunctioning up to 3000 cycles. On the other hand, in the comparative example, 200
An electronic component malfunctioned in the 0th cycle.

Similarly, electronic components (semiconductor components, capacitors, etc.) were soldered to an alumina substrate in the same manner as described above using the solder materials of the first and second embodiments. Then, a cold and heat durability test was conducted in which a cold and heat cycle from -50°C (30 minutes) to 125°C (30 minutes) was repeated many times. In this case, in the first example and the second example, thermal durability of 3,000 cycles or more was obtained, but in the comparative example, malfunction of the electronic component occurred after 2,500 cycles.

[Effects of the Invention] According to the solder material of the present invention, since intermetallic compounds that can become crystal nuclei are dispersed in the solder metal when the solder metal solidifies, the strength of the soldered part where the solder metal solidifies is improved. It is advantageous for In particular, soldering requires strength at high temperatures.
For example, heat resistance and cold durability can be improved.

Therefore, it is particularly suitable for use in in-vehicle electronic equipment that is used in harsh environments.

Claims (1)

[Claims] (1) A solder material comprising a solder metal and an intermetallic compound that is dispersed in the solder metal and can become crystal nuclei when the solder metal solidifies.