CN114346520A - A kind of Sn-Zn-Bi-In lead-free solder and preparation method thereof - Google Patents

Abstract

The invention discloses a Sn-Zn-Bi-In lead-free solder. Each component includes 8% of Zn, 0-8% of Bi, and 0.5% of In by mass percentage, and the sum of the mass percentages of the above components is 100% The present invention also discloses its preparation method, each raw material is weighed by mass percentage, and each component is cleaned after weighing; the Sn and Zn that are weighed are put into a quartz crucible for melting, poured into a mold to obtain alloy 1 Alloy 1 and Bi, In are melted, pour into the mould and obtain alloy 2; Pour the smelted alloy 2 into mould cooling to obtain Sn-Zn-Bi-In lead-free solder. The material of the invention is eco-friendly, has wide raw material sources, low cost, lower melting point and better mechanical properties. By adding alloying elements such as bismuth and bismuth, the comprehensive properties of Sn-Zn-Bi-In lead-free solder can be improved, such as wettability, oxidation resistance, mechanical properties, and electrical conductivity.

Description

A kind of Sn-Zn-Bi-In lead-free solder and preparation method thereof

technical field

The invention belongs to the technical field of electronic production, and relates to a Sn-Zn-Bi-In lead-free solder.

The invention also relates to a preparation method of Sn-Zn-Bi-In lead-free solder.

Background technique

At present, tin-lead solder in the domestic electronic circuit industry is extremely widely used and the amount is huge, which has made outstanding contributions to the growth of my country's GDP. The high lead content of traditional solder has attracted widespread attention. my country's industrial lead-free journey is long and arduous, and lead-free electronic products have been put on the agenda early, not only for the saving of industrial costs and the safety of industrial products, but also for my country's environmental protection. After a long exploration, related researchers found Sn-In, Sn-Cu, Sn-Bi and Sn-In and other considerable binary lead-free solder alloys, among which Sn-In, Sn-Zn showed better development potential. Because of its low cost and wide source of zinc, Sn-Zn has good mechanical properties and Sn-Zn is the binary alloy whose melting point is closest to the traditional Sn-Pb solder. Therefore, in the development of lead-free solder, only Adding a reasonable trace amount of alloying elements, the industrialization of lead-free solder can be tested and large-scale production can be carried out without large-scale adjustment of the production process.

Adding a small amount of suitable elements to the solder can also improve its properties, such as improving wettability and electrical conductivity, lowering the melting point of the alloy, and effectively improving mechanical properties. Therefore, this paper will provide a certain theoretical basis for the production of new lead-free solder and the research and development of lead-free solder technology.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a Sn-Zn-Bi-In lead-free solder to improve the wettability, oxidation resistance, mechanical properties and electrical conductivity of the Sn-Zn-Bi-In lead-free solder.

Another object of the present invention is to provide a preparation method of Sn-Zn-Bi-In lead-free solder.

The first technical solution adopted in the present invention is that a Sn-Zn-Bi-In lead-free solder includes 8% Zn, 0-8% Bi, 0.5% In by mass percentage, and the balance is Sn .

The second technical solution adopted in the present invention is, a kind of preparation method of Sn-Zn-Bi-In lead-free solder, which is specifically implemented according to the following steps:

Step 1, respectively weigh 8% Zn, 0-8% Bi, In0.5% by mass percentage, and the balance is Sn, and wash each component after weighing;

Step 2: Pour the weighed Sn and Zn into a quartz crucible for melting, and pour into a mold to obtain alloy 1 after melting;

Step 3, melting alloy 1 with Bi and In, and pouring it into a mold after melting to obtain alloy 2;

Step 4, pour the smelted alloy 2 into the mold to cool to obtain Sn-Zn-Bi-In lead-free solder.

The second technical scheme of the present invention is also characterized in that:

Wherein, in step 2, the weighed Sn and Zn are subjected to powder alloying treatment by ball milling, the ball milling speed is 320r/min～350r/min, the ball milling time is 12h～14h, and the melting temperature is 400℃～550℃;

Wherein each component in step 1 is respectively pure Sn, pure Zn, pure Bi, pure In;

Wherein, in step 1, the cleaning process adopts ultrasonic cleaning, cleaning for 15 minutes, and drying after cleaning;

The melting process in step 2 is as follows: melting in a tube furnace in a vacuum environment, setting the temperature to be 420 ° C ~ 450 ° C, after the material is completely melted, holding the temperature for 25 minutes, and placing the heated brazing filler metal in the tube furnace Repeated smelting several times, and stirring;

The melting process in step 3 is as follows: melting in a tube furnace in a vacuum environment, setting the temperature to be 800 ° C ~ 1100 ° C, after the material is completely melted, holding the temperature for 25 minutes, and placing the heated brazing filler metal in the tube furnace After repeated smelting and stirring, it was finally poured into the mold to obtain alloy 2.

The beneficial effects of the present invention are:

The Sn-Zn-Bi-In lead-free solder of the present invention has improved mechanical properties such as shearing and tensile strength compared with other solders of the same series, has better electrical conductivity and good comprehensive performance; meanwhile, the raw materials are widely sourced , the cost is low, the melting point is close to the Sn-Pb binary eutectic solder, and the composition process can be mass-produced without major changes.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments.

The invention provides a Sn-Zn-Bi-In lead-free solder, each component in mass percentage includes 8% of Zn, 0-8% of Bi, 0.5% of In, and the balance of Sn;

The invention also provides a preparation method of Sn-Zn-Bi-In lead-free solder, which is specifically implemented according to the following steps:

Step 1: Weigh the solder components of Sn grains, Zn grains, Bi grains, and In grains with a purity of nearly 100%, according to the alloy composition, weigh the required grams with an electronic balance, and use ultrasonic cleaning to remove impurities in the alloy grains. 15min, dry after cleaning;

Step 2: Put Sn and Zn into a quartz crucible, and melt them in a vacuum environment. The temperature is set at 420-450 °C. After the materials are completely melted, keep the temperature for 25 minutes. The brazing filler metal is repeatedly smelted in the tube furnace for many times, stirred, and finally poured into the mold to obtain alloy 1;

Step 3, melting Alloy 1, Bi and In in a tube furnace in a vacuum environment, setting the temperature to 800-1100°C, after the material is completely melted, keep the temperature for 25 minutes, in order to ensure sufficient and uniform distribution of the brazing filler metal, the heating The completed brazing filler metal is smelted multiple times with stirring, and finally poured into the mold to obtain alloy 2;

Step 4, pour the smelted alloy 2 into the mold and wait for it to cool.

The functions and effects of each component alloying element of the Sn-Zn-Bi-In lead-free solder of the present invention are as follows:

Sn element can reduce the melting point of the solder, improve the spreading performance of the solder, and increase the shear strength;

Zn element can improve the hardness and shear strength of nails;

Bi element can increase the growth activation energy of the intermetallic compound Cu ₅ Zn ₈ in Sn-Zn alloy system, which can effectively inhibit the growth of Cu ₅ Zn ₈ compound, which is beneficial to improve the mechanical properties of the alloy; Bi element can improve the Sn-Zn alloy in the Spreadability on Cu.

In element can reduce the welding distance, refine the solder structure, and improve the corrosion resistance of the solder;

Example 1

The raw material components of a Sn-Zn-Bi-In lead-free solder are: 8% Zn, 0% Bi, 0.5% In, and the remainder of Sn, and the sum of the mass percentages of the above components is 100%.

The above-mentioned clean raw materials are mixed together according to their components and their respective proportions, smelted in a vacuum tube furnace, and pure argon gas is introduced. The preparation steps are as follows:

Step 1: Weigh the solder components such as Sn grains, Zn grains, Bi grains, and In grains with a purity of close to 100%, according to the alloy composition, weigh the required grams with an electronic balance, and use ultrasonic cleaning to remove surface impurities. minutes, washed and dried;

Step 2: Weigh 91.5g of Sn and 8g of Zn, put them into a quartz crucible, and melt them in a tube furnace under a vacuum environment. The brazing filler metal after heating is repeatedly smelted in a tube furnace for many times, stirred, and finally poured into a mold to obtain alloy 1;

Step 3: Melt alloy 1 and In 0.5g in a tube furnace in a vacuum environment, set the temperature to 1100°C, and keep the material for 25 minutes after the material is completely melted. The brazing filler metal is smelted for many times with stirring, and finally poured into the mold to obtain alloy 2;

Step 4, pour the smelted alloy 2 into the mold to cool.

The Sn-Zn-Bi-In lead-free solder prepared in Example 1 has a melting point of 205.6°C, a conductivity of 9.21Ms/m, a wetting angle of 73.44°, a solder joint tensile strength of 38.2MPa, and a hardness of 9.88HV. .

Example 2

The raw material components of a Sn-Zn-Bi-In lead-free solder are: 8% Zn, 2% Bi, 0.5% In, and the remainder of Sn, and the sum of the mass percentages of the above components is 100%.

The above-mentioned clean raw materials are mixed together according to their components and their respective proportions, smelted in a vacuum tube furnace, and pure argon gas is introduced. The preparation steps are as follows:

Step 1: Weigh the solder components such as Sn grains, Zn grains, Bi grains, and In grains with a purity of close to 100%, according to the alloy composition, weigh the required grams with an electronic balance, and use ultrasonic cleaning to remove surface impurities. minutes, washed and dried;

Step 2: Weigh 89.5g of Sn and 8g of Zn, put them into a quartz crucible, and melt them in a tube furnace under a vacuum environment. The brazing filler metal after heating is smelted for many times with stirring, and finally poured into the mold to obtain alloy 1;

Step 3, melt alloy 1, Bi 2g, In 0.5g in a tube furnace under vacuum environment, set the temperature to 1100°C, and keep the temperature for 25min after the material is completely melted. In order to ensure the uniformity of the solder, the heating The completed brazing filler metal is smelted multiple times with stirring, and finally poured into the mold to obtain alloy 2;

Step 4, pour the smelted alloy 2 into the mold to cool.

The Sn-Zn-Bi-In lead-free solder prepared in Example 2 has a melting point of 212.3°C, a conductivity of 8.99Ms/m, a wetting angle of 67.54°, a tensile strength of the solder joint of 45.3MPa, and a hardness of 9.32HV. .

Example 3

The raw material components of a Sn-Zn-Bi-In lead-free solder are: 8% Zn, 4% Bi, 0.5% In, and the remainder of Sn, and the sum of the mass percentages of the above components is 100%.

The above-mentioned clean raw materials are mixed together according to their components and their respective proportions, smelted in a vacuum tube furnace, and pure argon gas is introduced. The preparation steps are as follows:

Step 1: Weigh the solder components such as Sn grains, Zn grains, Bi grains, and In grains with a purity of close to 100%, according to the alloy composition, weigh the required grams with an electronic balance, and use ultrasonic cleaning to remove surface impurities. minutes, washed and dried;

Step 2: Weigh 87.5g of Sn and 8g of Zn, put them into a quartz crucible, and melt them in a tube furnace under a vacuum environment. The brazing filler metal after heating is smelted for many times with stirring, and finally poured into the mold to obtain alloy 1;

Step 3, melt alloy 1, Bi 4g, In 0.5g in a tube furnace under vacuum environment, set the temperature to 1100°C, and keep the temperature for 25min after the material is completely melted. In order to ensure the uniformity of the solder, the heating The completed brazing filler metal is smelted multiple times with stirring, and finally poured into the mold to obtain alloy 2;

Step 4, pour the smelted alloy 2 into the mold to cool.

The Sn-Zn-Bi-In lead-free solder prepared in Example 3 has a melting point of 209.8° C., a conductivity of 9.04 Ms/m, a wetting angle of 75.66°, a solder joint tensile strength of 39.1 MPa, and a hardness of 11.6 HV.

Example 4

The raw material components of a Sn-Zn-Bi-In lead-free solder are: 8% Zn, 6% Bi, 0.5% In, and the remainder of Sn, and the sum of the mass percentages of the above components is 100%.

The above-mentioned clean raw materials are mixed together according to their components and their respective proportions, smelted in a vacuum tube furnace, and pure argon gas is introduced. The preparation steps are as follows:

Step 1: Weigh the solder components such as Sn grains, Zn grains, Bi grains, and In grains with a purity of close to 100%, according to the alloy composition, weigh the required grams with an electronic balance, and use ultrasonic cleaning to remove surface impurities. minutes, washed and dried;

Step 2: Weigh 85.5g of Sn and 8g of Zn, put them into a quartz crucible, melt in a vacuum environment, and set the temperature to 450°C. After the materials are completely melted, keep the temperature for 25min. In order to ensure the uniformity of the solder, the heating is completed. The resulting brazing filler metal is smelted for many times with stirring, and finally poured into the mold to obtain alloy 1;

Step 3, melt alloy 1, Bi 6g, In 0.5g in a tube furnace under vacuum environment, set the temperature to 1100°C, and keep the temperature for 25min after the material is completely melted. In order to ensure the uniformity of the solder, the heating The completed brazing filler metal is smelted multiple times with stirring, and finally poured into the mold to obtain alloy 2;

Step 4, pour the smelted alloy 2 into the mold to cool.

The Sn-Zn-Bi-In lead-free solder prepared in Example 4 has a melting point of 211.6°C, a conductivity of 9.16Ms/m, a wetting angle of 75.16°, a tensile strength of the solder joint of 40.6MPa, and a hardness of 15.2HV. .

Example 5

The raw material components of a Sn-Zn-Bi-In lead-free solder are: 8% Zn, 8% Bi, 0.5% In, and the remainder of Sn, and the sum of the mass percentages of the above components is 100%.

The above-mentioned clean raw materials are mixed together according to their components and their respective proportions, smelted in a vacuum tube furnace, and pure argon gas is introduced. The preparation steps are as follows:

Step 1: Weigh the solder components such as Sn grains, Zn grains, Bi grains, and In grains with a purity of nearly 100%, according to the alloy composition, weigh the required grams with a balance, use ultrasonic cleaning to remove surface impurities, and clean for ten minutes. , dry after cleaning;

Step 2: Weigh 83.5g of Sn and 8g of Zn, put them into a quartz crucible, and melt them in a tube furnace under a vacuum environment. The brazing filler metal after heating is smelted for many times with stirring, and finally poured into the mold to obtain alloy 1;

Step 3: Melt alloy 1, Bi 8g, In 0.5g in a tube furnace under vacuum environment, set the temperature to 1100°C, and keep the temperature for 25min after the material is completely melted. In order to ensure the uniformity of the solder, the heating The completed brazing filler metal is smelted multiple times with stirring, and finally poured into the mold to obtain alloy 2;

Step 4, pour the smelted alloy 2 into the mold to cool.

The Sn-Zn-Bi-In lead-free solder prepared in Example 5 has a melting point of 215.1°C, a conductivity of 9.34Ms/m, a wetting angle of 72.55°, a tensile strength of the solder joint of 40.6MPa, and a hardness of 15.48HV. .

Through experimental comparison, it can be found that the melting point of the Sn-Zn-Bi-In lead-free solder is significantly lower than that of the same series of solder, the hardness is also improved, and the electrical conductivity and the tensile strength of the solder joint are improved. The overall performance has been significantly improved.

Claims (7)

1. The Sn-Zn-Bi-In lead-free solder is characterized by comprising 8% of Zn, 0-8% of Bi, 0.5% of In and the balance of Sn In percentage by mass.

2. A preparation method of Sn-Zn-Bi-In lead-free solder is characterized by comprising the following steps:

step 1, weighing 8% of Zn, 0-8% of Bi, 0.5% of In and the balance of Sn according to the mass percentage, and cleaning the components after weighing;

step 2, pouring the weighed Sn and Zn into a quartz crucible for melting, and pouring the melted Sn and Zn into a mold to obtain an alloy 1;

step 3, melting the alloy 1, Bi and In, and pouring the melted alloy into a mold to obtain an alloy 2;

and 4, pouring the smelted alloy 2 into a mold for cooling to obtain the Sn-Zn-Bi-In system lead-free solder.

3. The method for preparing Sn-Zn-Bi-In lead-free solder according to claim 1, wherein In the step 2, the weighed Sn and Zn are subjected to powder alloying treatment by ball milling, the ball milling rotation speed is 320-350 r/min, and the ball milling time is 12-14 h; the melting temperature is 400-550 ℃.

4. The method for preparing the Sn-Zn-Bi-In lead-free solder according to claim 1, wherein each component In the step 1 is pure Sn, pure Zn, pure Bi and pure In.

5. The method for preparing the Sn-Zn-Bi-In lead-free solder according to claim 1, wherein the cleaning process In the step 1 is ultrasonic cleaning, cleaning for 15min, and drying after cleaning.

6. The method for preparing the Sn-Zn-Bi-In based lead-free solder according to claim 1, wherein the melting process In the step 2 is as follows: melting in a tubular furnace under a vacuum environment, setting the temperature to be 420-450 ℃, preserving the heat for 25min after the materials are completely melted, repeatedly melting the heated brazing filler metal in the tubular furnace for many times, and stirring.

7. The method for preparing the Sn-Zn-Bi-In based lead-free solder according to claim 1, wherein the melting process In the step 3 is as follows: melting in a tube furnace under a vacuum environment at 800-1100 ℃, preserving heat for 25min after the materials are completely melted, repeatedly melting the heated brazing filler metal in the tube furnace for many times, stirring, and finally pouring into a mold to obtain alloy 2.