JP2001191196A - Sn BASE Pb-FREE SOLDER EXCELLENT IN WETTABILITY, HEAT CYCLE CHARACTERISTICS AND OXIDATION RESISTANCE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Sn base Pb-free solder having wettability close to that of an Sn-Pb eutectic alloy and also excellent mechanical property and oxidation resistance. SOLUTION: This Pb-free solder having wettability close to that of an Sn-Pb eutectic alloy and also excellent mechanical property and oxidation resistance is obtained by adding Sb, Te or/and P to an Sn-Cu base alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Sn-based Pb-free solder having wettability close to that of a Sn-Pb eutectic alloy, excellent mechanical properties, and excellent oxidation resistance.

[0002]

2. Description of the Related Art Conventionally, as a solder alloy, an alloy in the vicinity of a Sn-Pb eutectic composition is known as a typical one.

[0003] However, in recent years, lead has been dissolved in acid rain, and the dissolved lead has significantly deteriorated the global environment.
There is a strong demand for a substitute material for the Pb eutectic alloy.

Typical examples of the Sn-based Pb-free solder developed to date include Sn-Ag based and Sn-Ag-Cu.
System, Sn-Ag-Bi-Cu system, Sn-Zn system, Sn-
Cu-based and the like can be mentioned.

[0005] These alloys have excellent mechanical properties compared to Sn-Pb eutectic alloys, but have a high melting point and poor wettability, so that the incidence of poor soldering is high.
There was a drawback that a large amount of oxide was generated.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a Sn-P
b Has wettability close to eutectic alloys and excellent mechanical property values,
Moreover, an object of the present invention is to provide a Sn-based Pb-free solder having excellent oxidation resistance.

[0007]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and found that Sn-Cu based alloys have
b, and Te or / and P, more preferably Ge, are added to provide P having excellent wettability close to that of a Sn-Pb eutectic alloy and excellent mechanical property values, and having excellent oxidation resistance.
The inventors have found that b-free solder can be obtained, and have reached the present invention.

[0008] That is, the present invention relates to a method of adding Sb
And Te or / and P are added.

[0009] The invention according to claim 3 provides the above-mentioned claim 1.
Ge is added to the Pb-free solder described in No. 4, but the wettability is improved by adding Ge.
The strength can be improved to a level close to the eutectic alloy without lowering the elongation.

Further, the invention according to claim 4 is the one in which Ge and Ni are added to the Pb-free solder according to claim 1 described above. In addition to the effects described, the strength can be further improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the addition amounts of the respective components are as follows: a Sn base alloy containing 0.1 to 1.5 wt% of Cu;
0.1 wt% or / and P0.0001-0.1 wt%
Should be added.

By setting the addition range as described above, the wettability is almost the same as that of the Sn-Pb eutectic alloy,
Oxide generation in Sn-Pb eutectic alloys and other Sn-based P
b) Sn-based P with excellent oxidation resistance, 1/2 of free solder, and excellent mechanical properties (strength, elongation, heat cycle properties)
b-free solder is obtained.

The Sn—Cu-based alloy has an amount of S within the above range.
By adding b, Te and / or P, the pull-out force in the meniscograph, which is related to the rate of occurrence of bridges in soldering, is reduced, so that good solderability is exhibited.

If the amount of Sb is less than 0.01% by weight, the above effect is reduced, and if it exceeds 1.0% by weight, the melting point is increased, so that the solderability at about 250 ° C. is hindered. For this reason, the addition range of Sb is 0.01 to 1.0 wt.
% Is good.

Te and P mainly serve to reduce the amount of oxides generated. Te is 0.001w
If the amount is less than t%, the effect is not obtained. If the amount is more than 0.1% by weight, the fluidity of the solder is reduced, and poor soldering occurs. Therefore, the range of addition of Te is 0.001 to 0.1.
wt% is good.

If the content of P is less than 0.0001 wt%, there is no effect. If the content of P is more than 0.1 wt%, the fluidity of the solder is reduced, and poor soldering occurs. Then, P
Is preferably 0.0001 to 0.1 wt%.

Ge has the effect of improving the wettability and the strength without lowering the elongation, and exhibits its effect with a small amount.
%, There is no effect, and if it is too large, elongation decreases and dross-like products are generated, and the apparent amount of oxides generated increases. Therefore, the addition range of Ge is set to 0.1.
002 to 0.5 wt%.

When Ni is used in combination with Ge, the effect of adding Ge can be maintained and the strength can be further improved.
Ni exerts its effect with a small amount, but 0.005 wt.
%, The effect is ineffective, and when it is too large, elongation is reduced and dross-like products are generated, and the apparent amount of oxides generated is increased. Therefore, the addition range of Ni is limited to 0.005 to 0.1 wt%.

The addition of only Ge or / Ge and Ni has little effect on the wettability, but the co-addition with Sb, Te and / or P can reduce the pulling force.

The k value, which is an index of the thermal cycle, is such that the Sn—Pb eutectic solder is 0.15
On the other hand, it is as low as about 0.027, and the thermal cycle characteristics are superior to those of the Sn-Pb eutectic solder.

According to the present invention, the k value is improved to about 0.012 to 0.020 by adding Sb and Te (or / and P) in the above range to the Sn-Cu base alloy.

The amount of oxide generation measured at 250 ° C. is Te
The effect is small when used alone, but is significantly improved when used in combination with Sb or Ge. Specifically, according to the present invention, the amount of oxide generation can be reduced to 40 to 60 g / kg · hr, which is about half that of conventionally known lead-free solder. However,
If the added amount of Ge and Te exceeds 0.1 wt%, dross-like products are generated, and the apparent amount of oxides increases.

As described above, the elements contained in the Sn—Cu-based alloy of the present invention have improved wettability, mechanical properties and oxidation resistance due to the synergistic effect of a plurality of elements, rather than a single element. It is.

Next, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

[0025]

EXAMPLES 8 kg of each metal of Examples (No. 1 to No. 6) and Comparative Examples (No. 8 to No. 13), which were blended to have the composition shown in Table 1 below, were melted at 300 ° C., and stirred sufficiently.
It was poured into a mold at about 50 ° C.

The obtained casting was measured for wettability and oxide generation. A JIS No. 4 test piece was prepared from the casting by machining, and the mechanical properties (strength, elongation and k value) were measured by a tensile test. The results are shown in Table 2 below. The test method was performed as follows.

(Wettability) Evaluation was made using a meniscograph. For meniscograph, the test piece shall be immersed in the molten solder at the specified temperature at a certain speed to a certain depth, pulled out after holding for a certain time, the buoyancy applied to the test piece during the test and the test piece getting wet with the molten solder. Was measured as a wetting time (zero cross time) and a pulling force (a force applied to the test piece when the test piece was separated from the molten solder).

The shorter the wetting time and the smaller the pulling force, the better the wettability.

(Mechanical property values) The strength and elongation were determined by a tensile test.

The thermal cycle characteristics were determined using the k value (strain rate sensitivity index m dependency on strain amount) as an index. The k value is positive, and the smaller the value, the less the creep deformation at the location where the strain is accumulated, which means that the thermal cycle characteristics are excellent.
This k value was determined as follows.

FIG. 1A is a schematic view of a load-elongation curve (stress-strain curve) of solder. The operation of reducing the strain rate by one digit during the tensile test (P _A → P _A ′) and returning it to the original state is repeated several times until the test piece breaks. The m value is obtained from the following equation (1), and the m value and the m value are obtained. Is plotted, and as shown in FIG. 1B, the m value and the strain (stra) are plotted.
in). The k value was determined from the slope of this straight line. The results are shown in Table 2 below.

[0032] m ₌ Log in _{(P A / P A ')} / Log (v / v') (1) ( formula, load cases _{P A} is the strain rate is fast, _{P A} 'if the strain rate is slow The load, v is the strain rate when the strain rate is high, and v 'is the strain rate when the strain rate is low.)

(Oxidation resistance) The oxidation resistance was evaluated by the following method. 2 kg of each solder alloy was placed in a magnetic evaporation dish with a diameter of 160 mm, heated to 250 ° C. and melted, and then stirred at a speed of 60 times per minute with a three-blade stirrer having a rotation diameter of 120 mm, and then stirred for 30 minutes. The oxide was collected and weighed three times every minute.

[0034]

[Table 1]

[0035]

[Table 2] As is clear from the results in Table 2, the solder alloy of the composition range of the present invention has a wettability, in particular, a pulling force close to that of the Sn-Pb eutectic alloy, and has the same strength and elongation as other Sn-Cu-based alloys. is there. However, the index (k value) of the heat cycle characteristic is S
n-Pb eutectic alloy and other Sn-Cu-based Pb-free solder alloys are remarkably superior, and the amount of oxide generation is Sn
-40 to 50% less than Pb eutectic alloy.

[0036]

As described above, according to the present invention, the wettability is almost equal to that of the Sn-Pb eutectic solder, and the workability is excellent. Since the amount of Pb-free solder, which is about half that of the conventionally known Pb-free solder and has improved oxidation resistance and does not contain Pb which is harmful to the environment, can be provided, it greatly contributes to the improvement of the global environment.

[Brief description of the drawings]

FIG. 1A is a schematic diagram of a load-elongation curve of a solder in a tensile test, and FIG. 1B is a diagram illustrating a relationship between an m value and a k value.

Claims (6)

[Claims] 1. An S-containing alloy containing Cu and Sb, Te or / and P, with the balance being Sn and unavoidable impurities, and having excellent wettability, heat cycle characteristics and oxidation resistance.
n-base Pb-free solder. 2. Cu 0.1-1.5 wt%, Sb 0.01
2. The Pb-free solder according to claim 1, containing 1.0 to 1.0 wt% and 0.001 to 0.1 wt% Te and / or 0.0001 to 0.1 wt% P. 3. 3. The Pb-free solder according to claim 1, further comprising Ge. 4. The Pb-free solder according to claim 1, further comprising Ge and Ni. 5. The Pb-free solder according to claim 2, containing 0.002 to 0.5 wt% of Ge. 6. 0.002 to 0.5 wt% of Ge and Ni
The P according to claim 2, which contains 0.005 to 0.1 wt%.
b Free solder.