CN113996967B

CN113996967B - Medium-temperature melting point alloy and application thereof

Info

Publication number: CN113996967B
Application number: CN202110953452.1A
Authority: CN
Inventors: 陈钦; 罗登俊; 徐华侨; 胡文学; 郭响
Original assignee: Eunow Electronic Technology Co ltd Suzhou
Current assignee: Eunow Electronic Technology Co ltd Suzhou
Priority date: 2021-08-19
Filing date: 2021-08-19
Publication date: 2023-04-28
Anticipated expiration: 2041-08-19
Also published as: CN113996967A

Abstract

The invention relates to the technical field of welding, and belongs to the IPC (industrial personal computer) classification number B23K35/26, in particular to a medium-temperature melting point alloy and application thereof. The medium-temperature melting point alloy comprises the following raw materials In percentage by mass: 10-18%, bi:0.6-1.5%, ag:0.2-0.8% and Sn to 100%. According to the invention, the impact and damage of high-temperature heat to devices during welding can be reduced while the welding temperature is reduced through the synergistic effect of La, co, in and other raw materials, and particularly the occurrence of NWO (non-wetting open circuit) defects can be reduced or avoided, so that the reliability and the production yield of products are greatly improved, the weldability of alloy solder is improved due to a specific formula design, and meanwhile, the welding void ratio is small.

Description

Medium-temperature melting point alloy and application thereof

Technical Field

The invention relates to the technical field of welding, and belongs to the IPC (industrial personal computer) classification number B23K35/26, in particular to a medium-temperature melting point alloy and application thereof.

Technical Field

The melting point of the sac-based solder is generally higher than 240 ℃ and the soldering temperature is generally higher than 240 ℃, so that the soldering temperature is reduced, the low-temperature solder commonly used at present is tin-bismuth-based solder, the melting point of the tin-bismuth-based solder is 138 ℃, and the soldering temperature is about 170 ℃, but the tin-bismuth-based low-temperature solder has high brittleness.

Patent CN105195915B discloses a low temperature lead-free solder alloy, but the applicant found that although this low temperature lead-free solder alloy can reduce the soldering temperature to some extent during use, the low temperature lead-free solder alloy has the disadvantage of greater brittleness due to the addition of a large amount of Bi to the system; patent CN101554687B discloses a novel medium-temperature aluminum brazing wire, although the medium-temperature aluminum brazing wire has good mechanical properties, because a large amount of Zn phases in the welding wire have close-packed hexagonal structures and are brittle phases at room temperature, the toughness of the welding wire is poor, and the addition of trace elements such as Si in a system easily causes a phenomenon of stress grafting, so that a cavitation phenomenon of a material is easy to occur.

Disclosure of Invention

The invention aims to provide a solder of a medium-temperature melting point alloy, which solves the defects of high welding temperature and high brittleness of a tin-bismuth solder in the prior sac system, and simultaneously has small void ratio when the prepared medium-temperature melting point alloy solder is used.

The technical scheme for realizing the invention is as follows:

first aspect: the medium temperature melting point alloy comprises the following raw materials In percentage by mass: 10-18%, bi:0.6-1.5%, ag:0.2-0.8% and Sn to 100%.

Preferably, the medium temperature melting point alloy comprises the following raw materials In percentage by mass: 13-16%, bi:0.6-1.5%, ag:0.2-0.8% and Sn to 100%.

Preferably, the medium temperature melting point alloy comprises the following raw materials In percentage by mass: 15%, bi:0.8-1.2%, ag:0.4-0.6% and Sn to 100%.

In the prior art, more solders are used as sac-series solders, the melting point is 217-227 ℃, the welding temperature is generally higher than 240 ℃ and the low-temperature tin-bismuth solders, the melting point is 138 ℃, the welding temperature is about 170 ℃, although the low-temperature Wen Xibi solders reduce the welding temperature to a certain extent, but the low-temperature Wen Xibi solders have the problem of larger brittleness, and the weldability of 20In alloy products In the prior art is poorer, in the invention, the melting point of the alloy can be well controlled by adding trace elements Bi and Ag, and the melting point of the alloy can be well controlled by controlling the mass fraction of special In to 15%, so that the alloy has good weldability, the void ratio of welding is reduced to a certain extent, more surprising is that the problem of larger brittleness of the low-temperature Wen Xibi solders is reduced, and the possibility is that the addition of a specific amount of Ag increases the weldability of the alloy solders, and the Ag element jointly acts well In balance with the melting point of the Sn-In, and the void ratio of the alloy is well balanced when the alloy is used by the applicants, so that the toughness of the alloy is better when the brazing structure is increased.

Preferably, the raw material of the medium temperature melting point alloy comprises 0.001-0.002% of group VIII transition metal by mass percent.

The VIII group transition metal is selected from at least one of Ni, rh, ru, co, ir, pd, pt.

Preferably, the group VIII transition metal is Co, i.e., in some embodiments, the medium temperature melting point alloy comprises, in:15%, bi:0.8-1.2%, ag:0.4-0.6%, co:0.001-0.002%, sn is added to 100%.

The applicant researches find that trace amount of VIII group transition metal, especially Co element, can well increase the mechanical property of the material, probably because Co can refine grains in a system by the synergistic effect of the Co element and Ag, promote high Wen Shi phase transformation, refine Bi phase and beta-Sn phase, and the Co can possibly have stable gamma phase, so that the grain boundary in the alloy solder is increased, the mutual intersection degree of the system is increased, and the mechanical property of the alloy solder is better increased.

Further preferably, the medium temperature melting point alloy comprises the following raw materials In percentage by mass: 15%, bi:1%, ag:0.4-0.6%, co:0.0015% and Sn were supplemented to 100%.

In the research, the applicant found that the Co content cannot be too high, but if the Co content is too high, it will affect the toughness of the alloy solder, and the cavitation phenomenon is easy to occur during the welding process, probably because Co has a close-packed hexagonal structure and is easy to be in brittle phase at room temperature, so that the toughness of the alloy solder is affected.

Preferably, the raw materials of the medium-temperature melting point alloy comprise 0.004-0.01% of rare earth metal by mass percent.

Preferably, the raw material of the medium-temperature melting point alloy comprises 0.005-0.08% of rare earth metal by mass percent.

The rare earth metal is selected from at least one of Sc, la, ce, gd, Y.

Preferably, the rare earth metal is La, i.e., in some embodiments, the starting material of the medium temperature melting point alloy includes, in:15%, bi:1%, ag:0.4-0.6%, co:0.0015%, la:0.005-0.08%, sn is added to 100%.

Preferably, the medium temperature melting point alloy comprises the following raw materials In percentage by mass: 15%, bi:1%, ag:0.5%, co:0.0015%, la:0.006% Sn is added to 100%.

The applicant found that in the present invention, although the addition of Ag increases the solderability of the alloy solder to some extent, the addition of Ag may cause impact and damage to the device by high temperature heat during soldering, probably because Ag is imagined to some extent or causes stress concentration, and through extensive research, the applicant found that adding a trace amount of La in the present application can avoid reducing or avoiding the occurrence of NWO (non-wetting open circuit) defects. Therefore, the reliability and the production yield of the product are greatly improved, probably because La can reduce the surface energy of alloy solder, so that the interface energy between the alloy solder and equipment, more importantly, la can reduce the oxidation-prone performance of In through the synergistic effect of Co, and the defect that an oxide film can be formed due to the formation of the alloy solder is reduced or avoided, so that the alloy solder can be fully wetted on a base material, in can reduce the welding temperature through the synergistic effect of In and other metals, and meanwhile, the impact and damage of high-temperature heat to a device during welding can be reduced.

In a second aspect, the medium temperature melting point alloy is used to prepare solder.

The solder comprises soldering lug, stick, tin wire and tin paste.

In some embodiments, the solder is a lug; the preparation method of the soldering lug comprises the following steps:

(1) Weighing the raw materials of the medium-temperature melting point alloy in corresponding parts by mass for later use;

(2) Adding the raw materials of the medium-temperature melting point alloy into a heating furnace, and then melting, stirring and mixing under the protection of nitrogen at 200-350 ℃;

(3) Preserving the temperature of the melted alloy for 1-8 hours in a stirring state, and then casting and cooling to obtain a solder alloy ingot;

(4) The solder alloy ingot is rolled into solder wires with the diameter of 2-12 mm through an extruder;

(5) The solder wire is pressed into a sheet of a desired thickness using a calendaring apparatus and the desired shape is stamped using a stamping apparatus to obtain a preformed solder tab.

In some embodiments, the pre-coated soldering lug can also be prepared by coating the surface of the prepared soldering lug with pre-coated soldering flux according to requirements.

The welding flux prepared by the medium-temperature melting point alloy can be a copper sheet or a corresponding welding pad, and is generally made of pure copper (comprising osp), electroplated nickel, silver plating, nickel gold and tin plating.

1. In is added to reduce the elongation of the alloy to a certain extent, the synergistic effect of the rare earth element and Co is added to better improve the high-temperature elongation of the soldering lug, improve the performance of the hot working process and reduce the cracking linearity, probably because the synergistic effect of the rare earth element, co and Ag can refine grains and promote the phase transition of high Wen Shi;

2 in the invention, co and Ag can well nucleate in the system under the action of rare earth elements, but the content of Ag cannot be excessive, otherwise, the problem of stress concentration can be caused, and 0.5% of Ag can effectively increase the mechanical property of the soldering lug under the action of other components.

3. Compared with the prior art, the alloy solder can have a melting point of about 180-200 ℃, and the defect of high brittleness of the tin-bismuth low-temperature solder is overcome by the synergistic effect of the raw materials such as Co, in and the like In the system;

4. compared with the prior art, the invention reduces the welding temperature and simultaneously reduces the impact and damage of high-temperature heat to the device during welding through the synergistic effect of La, co, in and other raw materials, and particularly reduces or avoids the occurrence of NWO (non-wetting open circuit) defects, thereby greatly improving the reliability and the production yield of the product;

5. compared with the prior 20In, the invention increases the weldability of the alloy solder through a specific formula design, and simultaneously ensures that the void ratio of welding is very small.

Drawings

FIGS. 1-3 are photographs of post-weld inspection using flux SPR-Z800XC in example 1; FIGS. 4-6 are photographs of post-weld inspection using flux SPR-Z800XC in example 1; FIGS. 7-9 are photographs of post-weld inspection using flux SPR-Z800XC in example 2; FIGS. 10-12 are photographs of post-weld inspection using flux SPR-Z800XC in example 2; FIGS. 13-15 are photographs of post-weld inspection using flux SPR-Z800XC in example 3; FIGS. 16-18 are photographs of post-weld inspection using flux SPR-Z800XC in example 2; FIGS. 19-21 are images of SAC305 lug post-weld inspection using flux SPR-Z800 XC; FIGS. 22-24 are pictures of SAC305 lug post-weld inspection using flux SPR-Z800 XC; FIGS. 25-27 are photographs of SnSb5 chips inspected after soldering using a flux SPR-Z800 XC; FIGS. 28-30 are photographs of SnSb5 chips inspected after soldering using a flux SPR-Z800 XC;

Detailed Description

The technical scheme of the invention is further specifically described below through examples and with reference to the accompanying drawings.

Example 1

A first aspect of example 1 provides a medium temperature melting point alloy comprising, in mass fraction: 15%, bi:1%, ag:0.5%, co:0.0015%, la:0.006% Sn is added to 100%.

A second aspect of embodiment 1 provides a bonding pad, the method for manufacturing the bonding pad comprising the steps of:

(1) Weighing the raw materials of the medium-temperature melting point alloy in corresponding parts by mass for later use; (2) Adding the raw materials of the medium-temperature melting point alloy into a heating furnace, and then melting, stirring and mixing the raw materials under the protection of nitrogen at 220 ℃; (3) Preserving the temperature of the melted alloy for 6 hours in a stirring state, and then casting and cooling to obtain a solder alloy ingot; (4) Passing the solder alloy ingot through an extruder, and calendaring into solder wires with the diameter of 6 mm; (5) The solder wire is pressed into a sheet of a desired thickness using a calendaring apparatus and the desired shape is stamped using a stamping apparatus to obtain a preformed solder tab.

Example 2

A first aspect of example 2 provides a medium temperature melting point alloy comprising, in mass fraction: 20%, ag:2.8% and Sn was added to 100%.

A second aspect of example 2 provides a bonding pad prepared in the same manner as example 1.

Example 3

A first aspect of example 3 provides a medium temperature melting point alloy comprising, in mass fraction: 20%, ag:2.8%, co:0.0015% and Sn were supplemented to 100%.

A second aspect of example 3 provides a bonding pad prepared in the same manner as example 1.

Performance testing

And (3) testing welding void rate: and detecting the cavitation phenomenon of the welded product by using the X-RAY, and calculating the cavitation rate of the welded product.

Test sample: the sample in the examples is the lug in examples 1-3; the comparative sample is a commercially available SAC305 lug and SnSb5 lug;

the soldering lug surface was coated with flux and then soldered to the copper pads, and the nitrogen reflux curve at the time of soldering was a conventional 305 curve, and 3 groups of samples were measured for each test sample.

The soldering fluxes are soldering flux SPR-Z800XC and soldering flux SPR Z800 of Shenzhen SpA environmental protection new material Co.

FIGS. 1-3 are pictures of the post-weld inspection of example 1 using flux SPR-Z800 XC; FIGS. 4-6 are photographs of post-weld inspection using flux SPR-Z800XC in example 1;

FIGS. 7-9 are photographs of post-weld inspection using flux SPR-Z800XC in example 2; FIGS. 10-12 are photographs of post-weld inspection using flux SPR-Z800XC in example 2;

FIGS. 13-15 are photographs of post-weld inspection using flux SPR-Z800XC in example 3; FIGS. 16-18 are photographs of post-weld inspection using flux SPR-Z800XC in example 2;

FIGS. 19-21 are images of SAC305 lug post-weld inspection using flux SPR-Z800 XC; FIGS. 22-24 are pictures of SAC305 lug post-weld inspection using flux SPR-Z800 XC;

FIGS. 25-27 are photographs of SnSb5 chips inspected after soldering using a flux SPR-Z800 XC; fig. 28-30 are post-weld inspection pictures of SnSb5 soldering tabs using flux SPR-Z800 XC.

The void fraction test results are shown in table 1:

TABLE 1

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Claims

1. The medium temperature melting point alloy is characterized in that the raw materials of the medium temperature melting point alloy comprise 0.001-0.002% of group VIII transition metal by mass percent; the VIII group transition metal is Co; the medium-temperature melting point alloy comprises 0.004-0.01% of rare earth metal by mass fraction; the rare earth metal is La; the medium-temperature melting point alloy comprises the following raw materials In percentage by mass: 10-18%, bi:0.6-1.5%, ag:0.2-0.8% and Sn to 100%.

2. The medium temperature melting point alloy according to claim 1, wherein the medium temperature melting point alloy comprises, in:13-16%, bi:0.6-1.5%, ag:0.2-0.8% and Sn to 100%.

3. The medium temperature melting point alloy according to claim 2, wherein the medium temperature melting point alloy comprises, in:15%, bi:0.8-1.2%, ag:0.4-0.6% and Sn to 100%.

4. The medium temperature melting point alloy as set forth in claim 1, wherein the raw material of the medium temperature melting point alloy includes 0.005-0.08% by mass of rare earth metal.

5. Use of a medium temperature melting point alloy according to any one of claims 1-4 for the preparation of solder.

6. The use of a medium temperature melting point alloy according to claim 5 wherein said solder comprises a tab, rod, wire, paste.