CN102059474B

CN102059474B - Environmentally friendly lead-containing solder capable of suppressing lead from volatilizing at high temperature

Info

Publication number: CN102059474B
Application number: CN2010105830640A
Authority: CN
Inventors: 杜长华; 黄伟九; 朱新才; 许惠斌; 陈方
Original assignee: Chongqing University of Technology
Current assignee: Chongqing University of Technology
Priority date: 2008-05-27
Filing date: 2008-05-27
Publication date: 2013-11-13
Anticipated expiration: 2028-05-27
Also published as: CN102059474A

Abstract

The invention provides an environmentally friendly lead-containing solder capable of suppressing lead from volatilizing at high temperature, which is used in the electronic industry. The lead-containing solder comprises the following components: 0-4.0 percent by weight of Ag, 0-3.0 percent by weight of Sb, one or more of Ni, Al, Bi, Ca, In, P and Ti and the balance of Sn and Pb, wherein the quantity of each of the Ni, the Al, the Bi, the Ca, the In, the P and the Ti is 0.0001-0.2 percent by weight; the total quantity of the elements of the Ni, the Al, the Bi, the Ga, the In, the P, the Ti, and the like does not exceed 0.3 percent by weight at most; and the elements can form various better combinations, such as the combination of Ni and P, the combination of Ni, P and Ti and the combination of Ni, P and Ga, or only the elements of the Ni, the Al, and the like are selected. In the invention, after the solder is molten, a surface modification film can be automatically generated and can obviously suppress the volatilization of the lead at high temperature, and the solder has good environment condition in a using process, has no influence on the health of operators, is safe and convenient to use and has low cost, thus the solder is a new-generation micro-connection material used for environmentally friendly manufacturing an electronic product.

Description

A kind of energy suppresses the plumbous at high temperature environment-friendly type solder containing lead of volatilization

The present invention is that application number is dividing an application of 200810069745.8 application for a patent for invention.

Technical field

The present invention relates at high temperature the volatilize solder containing lead of contaminated environment of inhibition lead that electron trade uses.

Background technology

For a long time, solder containing lead is widely used as the electronics brazing material with its cheap cost and excellent performance.Because lead has pollution to environment, the world has started the unleaded research of electronic brazing filler metal from the nineties in 20th century, but up to now, the lead-free brazing that does not find all the time a kind of combination property and Sn-Pb solder to match in excellence or beauty, do not find the comprehensive solution that substitutes Pb yet.In many electronic equipments, because of the reliability of lead-free brazing can not be guaranteed be difficult to really realize unleaded.Therefore, following electronic brazing filler metal will form general layout leaded and unleaded and that deposit.

Solder containing lead, to one of pollution channel of environment, is the boiling point lower (1751 ℃) due to lead, at high temperature can produce plumbous volatilization and contaminated air, and the serious harm people's is healthy, even causes operating personnel's lead poisoning.In order to improve workshop condition, the method one that generally adopts at present is the application lead-free brazing, the 2nd, establish the gas skirt exhausting on the top of soldering station.Although the former can fundamentally eliminate plumbous pollution, it is high that the lead-free brazing that uses exists fusing point, and brazing property is poor, need to use the high activity brazing flux and cause secondary pollution, and the defect such as price is high, waste is large; Although the latter can improve the air quality of electronic product production workshop, avoid operating personnel's lead poisoning, can cause severe contamination to atmosphere.How could both improve the soldering quality of connection, to avoid again the pollution in brazing process, both at home and abroad the solution that makes the best of both worlds of neither one still so far.Prevent the report of plumbous volatilization about other field, for example Chinese patent ZL90107046 has reported a kind of plumbous liquid surface dopant, the method adopts the mixture of many oxide to cover the effusion that suppresses plumbous steam on plumbous liquid surface, and airborne lead fume concentration is reduced.This coverture is mainly used in the patenting of steel wire and processes, and be not suitable for the electronics soldering, uses.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, the solder containing lead of the extremely low environment-friendly type easy to use of a kind of at high temperature self plumbous vapour pressure is provided.

Under the inhibition high temperature that the present invention proposes, the solder containing lead of plumbous volatilization is comprised of the component of following mass percent: Ag0～4.0wt%, Sb0～3.0wt%, with one or more in Ni, Al, Bi, Ga, In, P, Ti, the amount of every kind of element is 0.0001%-0.2%, and surplus is Sn and Pb.This solder is further characterized in that, the total amount of the elements such as Ni, Al, Bi, Ga, In, P, Ti is no more than 0.3wt% at the most in described solder.

In solder, the selection of the elements such as Ni, Al, Bi, Ga, In, P, Ti has following several combination preferably:

The one, select: Ni 0.005-0.2%, P0.001-0.1% make up, and can reach the effect that is difficult to detect plumbous volatilization in soldering.

The 2nd, select: Ni 0.005-0.2%, P0.001-0.1% and Ti0.0001-0.005% make up, and can reach the effect that is difficult to detect plumbous volatilization in soldering.

The 3rd, select: Ni 0.005-0.2%, P0.001-0.1% and Ga 0.0001-0.005% make up, and can reach the effect that is difficult to detect plumbous volatilization in soldering.

The 4th, select: Al 0.005-0.2%, Ni 0.001-0.01% and Ga 0.0001-0.005% combination can reach the effect that is difficult to detect plumbous volatilization in soldering.

The 5th, select: Al 0.005-0.2%, Bi 0.001-0.2% and In 0.0001-0.005% combination can make plumbous volatile quantity significantly descend.

The 6th, only select Ni 0.005-0.2%, plumbous volatile quantity is significantly reduced or be difficult to detect plumbous volatilization.

The 7th, only select Al 0.005-0.2%, plumbous volatile quantity is significantly descended.

Why the solder of the present invention's design can suppress volatilization plumbous under high temperature, is because it can spontaneous generation layer of surface Modified Membrane after fusing.Because this solder is dispersed in the surface modification elements such as micro-Ni, Al, Bi, Ga, In, P, Ti in brazing filler metal alloy, after solder fusing, according to Gibbs adsorption equation:

Wherein: Γ represents adsorbance, and C represents concentration, and R is gas constant, and T is thermodynamic temperature,

Be illustrated in the rate of change of constant temperature lower surface tension force with concentration.

When

＜0 o'clock, Γ＞0, be positive absorption this moment.Namely originally being dispersed in inner micro-surface modification element will make surface concentration greater than inner concentration from the trend apparent motion, and form fine and close Modified Membrane on surface.

On the liquid solder surface, plumbous vapour pressure can be expressed as

At a certain temperature, the saturated vapour pressure of pure lead

For definite value.Therefore, the size of plumbous vapour pressure depends primarily on activity coefficient plumbous in the liquid solder skin covering of the surface under brazing temperature

And molar fraction

.When the modifying element in molten solder is adsorbed to surface, can not only reduce molar fraction plumbous in skin covering of the surface

, and can reduce activity coefficient plumbous in skin covering of the surface

., due to the compactness of formed Modified Membrane, can significantly reduce plumbous diffusion velocity by oxide-film, thereby stop the transfer of lead atom to surface simultaneously.Therefore can significantly suppress exposure and the volatilization of lead in liquid solder under high temperature.

As seen, the remarkable advantage of solder of the present invention is under the prerequisite that keeps the solder containing lead function admirable, can suppress volatilization plumbous under high temperature, in use environmental condition is good, without impact, safe and convenient to use on operator ' s health, and cost is low, therefore, this solder is of new generation little connecting material that the electronic product green manufacturing is used.

The specific embodiment

Embodiment 1: the quality Pb that is Sn, the 370g of 630g is placed in the open type electric furnace and carries out refinement oxide and boiling refining; then inject sealed stove; add Al 0.5g and Ni 0.01g, Ga 0.005g to carry out the modification refining; the gained solder is heated to 800 ℃ with 10 ℃ of per minutes under protective atmosphere, record plumbous volatile quantity than Sn-37Pb decline 65 %.

Embodiment 2: be that the Ag of Pb, 20g of Sn, the 360g of 620g is placed in the open type electric furnace and carries out refinement oxide and boiling refining with quality; then inject sealed stove; add Al 0.1g and Bi 1.5g, In 0.05g to carry out the modification refining; the gained solder is heated to 800 ℃ with 10 ℃ of per minutes under protective atmosphere, record plumbous volatile quantity than Sn-37Pb decline 72 %.

Embodiment 3: be that the Sb of Pb, 20g of Sn, the 430g of 550g is placed in the open type electric furnace and carries out refinement oxide and boiling refining with quality; then inject sealed stove; add Ni 0.5g and P 0.05g, Ti 0.005g to carry out the modification refining; the gained solder is heated to 800 ℃ with 10 ℃ of per minutes under protective atmosphere, be difficult to detect plumbous volatilization.

Embodiment 4: change the interpolation element of embodiment 1 into Ni 0.1g and Ga 0.01g, P 0.05g, the gained solder is heated to 800 ℃ with 10 ℃ of per minutes under protective atmosphere, has been difficult to detect plumbous volatilization.

Embodiment 5: change the interpolation element of embodiment 1 into Ni 0.1g and P 0.05g, the gained solder is heated to 800 ℃ with 10 ℃ of per minutes under protective atmosphere, has been difficult to detect plumbous volatilization.

Embodiment 6: change the interpolation element of embodiment 1 into Ni 0.12g, the gained solder is heated to 800 ℃ with 10 ℃ of per minutes under protective atmosphere, has been difficult to detect plumbous volatilization.

Embodiment 7: change the interpolation element of embodiment 2 into Al 0.1g and carry out the modification refining, the gained solder is heated to 800 ℃ with 10 ℃ of per minutes under protective atmosphere, records plumbous volatile quantity than Sn-37Pb decline 62 %.

Claims

1. one kind can be suppressed the plumbous at high temperature environment-friendly type solder containing lead of volatilization, and it comprises the component of following mass percent: Sb0～3.0wt%, Al 0.005-0.2%, Bi 0.001-0.2% and In 0.0001-0.005%, and surplus is Sn and Pb.