CN113770589B

CN113770589B - Lead-free solder for high-performance electronic industry

Info

Publication number: CN113770589B
Application number: CN202111175602.7A
Authority: CN
Inventors: 王彩霞; 金霞; 刘平; 钟海锋; 冯斌; 张玲玲
Original assignee: Zhejiang Yatong New Materials Co ltd
Current assignee: Zhejiang Yatong New Materials Co ltd
Priority date: 2021-10-09
Filing date: 2021-10-09
Publication date: 2023-02-28
Anticipated expiration: 2041-10-09
Also published as: CN113770589A

Abstract

The invention discloses a lead-free solder for high-performance electronic industry, which comprises the following raw materials in percentage by weight: 0.6-0.8% of Cu0.6-1.5% of Bi, 0.02-0.04% of Nd0.04%, 0.04-0.06% of P, 0.002-0.01% of Ge0.01-0.05% of Ni0.01-0.05%, 0.03-0.05% of modified graphene and the balance of Sn. According to the invention, appropriate elements and modified graphene are added into Sn-0.7Cu and matched with each other, so that the solder has good wettability and oxidation resistance, and the formed welding spot has good mechanical properties and a reliable welding joint.

Description

Lead-free solder for high-performance electronic industry

Technical Field

The invention relates to the technical field of lead-free solders, in particular to a lead-free solder for a high-performance electronic industry.

Background

The use of n-Pb solder in the electronics industry has been in the last century and has formed a fully mature production process in long-term research and production practices. The solder has the advantages of good wettability, high reliability, low welding temperature, low heat loss and high stability. However, due to the great harm of Pb and Pb-containing compounds in Sn-Pb solder to environment and human health, a series of relevant regulations such as: WEEE, roHS directive and electronic information product pollution control management method to enforce the limitation of lead metal in electronic products. <xnotran> , Sn-Ag , sn-Cu , sn-Zn , sn-Bi , sn-Ag-Cu , . </xnotran> Among them, sn-Ag-Cu lead-free solder is considered as the most potential Sn-Pb solder substitute product because of its advantages of good wettability and thermal fatigue resistance. However, the lead-free solder has a high content of noble metal Ag, which results in high production cost, and the price of noble metal rises rapidly in recent years, which greatly limits the use of lead-free solder in large quantities. At present, sn-Cu lead-free solder is widely used due to wide raw material source, low cost and no toxic or side effect. The widely-used Sn-0.7Cu lead-free solder has higher applicability to the fuse tube packaging process and lower cost, but the wettability, the mechanical property and the oxidation resistance of the solder are lower than those of the traditional Sn-Pb solder, so that the yield of the soldered product is greatly reduced; with the trend of miniaturization, multifunctionality and low cost of new electronic products, the soldering process of electronic components has higher and higher performance requirements on lead-free solder, so that the improvement of the soldering process is needed.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides the lead-free solder for the high-performance electronic industry, and the lead-free solder has good wettability and oxidation resistance by adding appropriate elements and modified graphene in Sn-0.7Cu and mutually matching, so that the formed welding spot has good mechanical performance and the welding joint is reliable.

The invention provides a lead-free solder for high-performance electronic industry, which comprises the following raw materials in percentage by weight: 0.6-0.8% of Cu, 1-1.5% of Bi, 0.02-0.04% of Nd, 0.04-0.06% of P, 0.002-0.01% of Ge, 0.01-0.05% of Ni, 0.03-0.05% of modified graphene and the balance of Sn.

Preferably, in the preparation process of the modified graphene, a mixed solution of cobalt chloride, a reducing agent and graphene is taken, the mixed solution is subjected to heat preservation reaction at the temperature of 130-140 ℃ for 18-20h, solid-liquid separation is performed, and drying is performed to obtain the modified graphene.

Preferably, in the preparation process of the modified graphene, the reducing agent is sodium borohydride.

Preferably, in the preparation process of the modified graphene, the solvent of the mixed solution is ethylene glycol.

Preferably, in the preparation process of the modified graphene, the weight ratio of the cobalt chloride to the graphene is 1-1.5.

Preferably, in the preparation process of the modified graphene, the molar ratio of the cobalt chloride to the reducing agent is 1.

Preferably, the raw materials comprise the following components in percentage by weight: 0.7% of Cu, 1.3% of Bi, 0.03% of Nd, 0.05% of P, 0.008% of Ge, 0.03% of Ni, 0.045% of modified graphene and the balance Sn.

The lead-free solder can be processed into the forms of strips, rods, filaments, spheres, soldering paste and the like.

The preparation method comprises the following steps: the raw materials are uniformly mixed according to the parts by weight, then ball-milled, dried, pressed into blocks, smelted, cast and solidified to obtain the lead-free solder for the high-performance electronic industry.

Has the advantages that:

according to the invention, the graphene is modified to uniformly load cobalt on the surface of the graphene, so that the dispersibility of the graphene in the solder is improved; bi and P are added, the proportion of the Bi and the P is adjusted, the melting point of the solder can be reduced, the modified graphene is matched, the wettability of the solder is improved, and in addition, the problem of reduction of the hardness of a welding point caused by P element can be solved; by selecting a proper proportion of Bi and P, the influence of Bi and P on the hardness and creep resistance of the solder can be reduced as little as possible; proper amount of P and Ge are matched, so that the oxidation resistance of the solder can be improved, the density of a welding spot can be improved by matching with the modified graphene, the defects of cracks, pores and the like are reduced, and the oxidation resistance of the welding spot is further improved; the modified graphene is matched with Nd and Ni in a proper proportion, so that the interface reaction between the solder and the substrate can be effectively inhibited, the excessive growth of an interface compound layer is prevented, crystal grains are refined, the mechanical properties such as the shear strength of a welding spot are improved, and the reliability of the welding spot is improved; the solder can be used in the microelectronic industry.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.

Example 1

A lead-free solder for high-performance electronic industry comprises the following raw materials by weight percent: 0.6% of Cu, 1% of Bi, 0.02% of Nd, 0.04% of P, 0.002% of Ge, 0.01% of Ni, 0.03% of modified graphene and the balance of Sn;

in the preparation process of the modified graphene, 0.1g of cobalt chloride hexahydrate and 0.014g of sodium borohydride are added into a beaker and mixed uniformly, then 50ml of ethylene glycol is slowly added, then stirring is carried out for 5min at 300r/min, then 0.001g of graphene is added, ultrasonic dispersion is carried out for 0.5h, then the mixture is transferred into a reaction kettle, the temperature is increased to 130 ℃, heat preservation reaction is carried out for 20h, then cooling is carried out to the room temperature, centrifugation is carried out, the solid is washed by water and ethanol in sequence, then vacuum drying and grinding are carried out to obtain the modified graphene.

Example 2

A lead-free solder for high-performance electronic industry comprises the following raw materials by weight percent: 0.8% of Cu, 1.5% of Bi, 0.04% of Nd, 0.06% of P, 0.01% of Ge, 0.05% of Ni, 0.05% of modified graphene and the balance of Sn;

in the preparation process of the modified graphene, 0.15g of cobalt chloride hexahydrate and 0.024g of sodium borohydride are added into a beaker and mixed uniformly, then 50ml of ethylene glycol is slowly added, then stirring is carried out for 5min at the speed of 300r/min, then 0.001g of graphene is added, ultrasonic dispersion is carried out for 0.5h, then the obtained mixture is transferred into a reaction kettle, the temperature is raised to 140 ℃, the reaction is carried out for 18h under the condition of heat preservation, then the obtained product is cooled to the room temperature, centrifuged, the solid is washed by water and ethanol in sequence, and then the obtained product is dried in vacuum and ground to obtain the modified graphene.

Example 3

A lead-free solder for high-performance electronic industry comprises the following raw materials by weight percent: 0.65% of Cu, 1.4% of Bi, 0.035% of Nd, 0.055% of P, 0.006% of Ge, 0.04% of Ni, 0.04% of modified graphene and the balance of Sn;

in the preparation process of the modified graphene, 0.12g of cobalt chloride hexahydrate and 0.019g of sodium borohydride are added into a beaker and mixed uniformly, then 50ml of ethylene glycol is slowly added, then stirring is carried out for 5min at the speed of 300r/min, then 0.001g of graphene is added, ultrasonic dispersion is carried out for 0.5h, then the obtained mixture is transferred into a reaction kettle, the temperature is increased to 135 ℃, the reaction is carried out for 20h under the condition of heat preservation, then the obtained product is cooled to the room temperature, centrifuged, the solid is washed by water and ethanol in sequence, and then the obtained product is dried in vacuum and ground to obtain the modified graphene.

Example 4

A lead-free solder for high-performance electronic industry comprises the following raw materials by weight percent: 0.7% of Cu, 1.3% of Bi, 0.03% of Nd, 0.05% of P, 0.008% of Ge, 0.03% of Ni, 0.045% of modified graphene and the balance of Sn;

The preparation method of the above examples 1-4 is the same, and comprises the following steps: uniformly mixing the raw materials in parts by weight, pouring the mixture into a ball milling tank, wherein the ball-to-material ratio is 10.

Comparative example 1

The procedure of example 3 was repeated except that modified graphene was not added.

Comparative example 2

A lead-free solder comprises the following raw materials in percentage by weight: 0.7% of Cu and the balance of Sn.

The properties of examples 1 to 4 and comparative examples 1 to 2 were compared, and the results are shown in Table 1.

The wettability was tested according to GB11364-89 solder spreadability and caulking test method.

The function of the solder between the electronic component and the circuit board is simulated by adopting a lap welding mode, and then the shearing strength of the welding spot is detected by using a universal testing machine.

The method for detecting the oxidation resistance comprises the following steps: the lead-free solders of examples 1-4 and comparative examples 1-2 were placed on Al ₂ O ₃ Keeping the temperature of the crucible in a box type resistance furnace at 280 ℃ for 24h, cooling along with the furnace, and observing the brightness, the oxidation film condition and the surface smoothness condition of the surface of each combined gold; wherein, the lightness is represented by a symbol "+", the more the symbol, the better the lightness; the smoother surface is indicated by the "+" sign, and the more + the smoother the surface.

TABLE 1 test results

As can be seen from Table 1, the invention improves the wettability, mechanical property and oxidation resistance of the Sn-0.7Cu lead-free solder by matching the elements and the modified graphene in a proper proportion, and the welding joint is more reliable.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A lead-free solder for high-performance electronic industry is characterized by comprising the following raw materials in percentage by weight: 0.7% of Cu, 1.5% of Bi, 0.04% of Nd, 0.06% of P, 0.008% of Ge, 0.01% of Ni, 0.045% of modified graphene and the balance of Sn;

in the preparation process of the modified graphene, taking a mixed solution of cobalt chloride, a reducing agent and graphene, carrying out heat preservation reaction at 130-140 ℃ for 18-20h, carrying out solid-liquid separation, and drying to obtain the modified graphene;

in the preparation process of the modified graphene, the reducing agent is sodium borohydride;

in the preparation process of the modified graphene, the solvent of the mixed solution is ethylene glycol;

in the preparation process of the modified graphene, the weight ratio of cobalt chloride to graphene is 1-1.5;

in the preparation process of the modified graphene, the molar ratio of cobalt chloride to the reducing agent is 1.