Welding flux for SnAgCu alloy solder powder and preparation method thereof

A technology of flux and solder powder, applied in the field of flux and preparation of SnAgCu alloy solder powder, can solve the problems of shortening the service life of electronic products, corrosion of circuit boards and components, influence of brightness of solder joints, etc., and achieve excellent soldering. Performance and electrical safety, good thixotropy, good collapse resistance

Active Publication Date: 2009-08-19
NICHE TECH KAISER SHANTOU
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since lead-free solder paste contains more active agents and rosin resin, the chemical properties of rosin mainly depend on resin acid. The structural formula of resin acid contains two types of chemical substances, double bond and carboxylic acid. The resin acid in rosin The double bond has a strong chemical reactivity. Under the condition of high temperature and oxygen-containing welding, at the same time, when metal ions are used as a catalyst, the solder powder and oxygen undergo an oxidation reaction, and the resin acids polymerize with each other under the action of the catalyst. Reaction, the produced oxides and polymers have relatively long molecular chains and extremely poor fluidity. In this way, during the second half of reflow soldering, most of the residues composed of these oxides and polymers will remain on the soldering surface. The spot surface has poor fluidity, so there will be more residues covering the surface of the solder joints. Because of the large amount of residues, the thickness of the residues will be thicker, and the brightness of the solder joints will also be affected to a certain extent. , the residue still contains a small amount of active substances, and the residue adheres to the surface of the solder joint for a long time,

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The preparation method of the flux includes the following steps in sequence:

[0023] (1) 25 kg of organic solvent (10 kg of terpineol, 10 kg of diethylene glycol butyl ether, 5 kg of 2-methyl-2,4-pentanediol) and 55 kg of rosin (including 30 kg of esterified rosin Kilogram, hydrogenated rosin 25 kg) were mixed and added to the heating container, then heated, and the temperature in the heating container was controlled at 100 ° C;

[0024] (2) when the added rosin is completely melted, continue to control the temperature in the heating vessel at 100° C., add 5 kilograms of active agent (2.5 kilograms of hexadecanoic acid, 2,3-dibromo 1,4-butenediol) 0.5 kg, 2 kg of alkylphenol polyoxyethylene ether), 8 kg of thixotropic agent (both hydrogenated castor oil) and 7 kg of plasticizer (including 4 kg of dimethyl phthalate, 4 kg of diisophthalate 3 kilograms of nonyl esters) are added in the heating vessel, and stirred until rosin, activator, thixotropic agent and plasticizer...

Embodiment 2

[0028]The preparation method of the flux includes the following steps in sequence:

[0029] (1) 35 kilograms of organic solvents (wherein 15 kilograms of dipropylene glycol methyl ether, 10 kilograms of diethylene glycol, 10 kilograms of ethyl acetate) and 47 kilograms of rosin (both are polymerized rosin) are mixed and added to the heating vessel, Then heat, and control the temperature in the heating container at 120°C;

[0030] (2) when the added rosin is completely melted, continue to control the temperature in the heating container at 120 ° C, 8 kilograms of active agents (3 kilograms of dodecanoic acid, 4 kilograms of octadecanoic acid, 0.5 kilograms of benzoic acid, fluorocarbon surface 0.5 kg of active agent), 5 kg of thixotropic agent (all of which are ethylene bis-stearic acid amide) and 5 kg of plasticizer (including 3 kg of didecyl phthalate, 2 kg of dioctyl phthalate) ) is added to the heating vessel, and stirred until the rosin, the active agent, the thixotropic ...

Embodiment 3

[0034] The preparation method of the flux includes the following steps in sequence:

[0035] (1) 40 kilograms of organic solvent (including 25 kilograms of propylene glycol phenyl ether, 5 kilograms of butyl acetate, 5 kilograms of hexadecanol, and 5 kilograms of methyl propanol) and 30 kilograms of rosin (including 20 kilograms of fully hydrogenated rosin, water white hydrogenated 5 kilograms of rosin and 5 kilograms of disproportionated rosin) were added to the heating container after mixing, and then heated, and the temperature in the heating container was controlled at 130 ° C;

[0036] (2) when the added rosin is completely melted, continue to control the temperature in the heating container at 130 ° C, add 10 kilograms of active agent (both are nonylphenol polyoxyethylene ether), 10 kilograms of thixotropic agent (wherein ethylene glycol 5 kg of bis-stearic acid amide, 5 kg of castor oil) and 10 kg of plasticizer (both diisoundecyl phthalate) were added to the heating co...

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PUM

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Abstract

The invention relates to a soldering flux for Sn-Ag-Cu alloy solder powder, which is characterized by comprising the following compositions in proportion by weight: 25 to 40 percent of organic solvent, 5 to 10 percent of activating agent, 30 to 55 percent of rosin, 5 to 10 percent of thixotropic agent, and 5 to 10 percent of plasticizing agent. The invention also provides a preparation method for the soldering flux. In the invention, the plasticizing agent strengthens the liquidity of residues, so that soldering paste prepared from the soldering flux and the Sn-Ag-Cu alloy solder powder has few residues after welding and can be well spread around welding spots; the residues are transparent so as to ensure good brightness of the welding spots; the corrosion of the residues to the welding spots and components and parts is greatly reduced at the same time; and the proper amount of thixotropic agent makes the soldering paste prepared from the soldering flux and the Sn-Ag-Cu alloy solder powder have high stability and good thixotropic property, and the soldering paste has good sagging resistance in printing and welding, and reduces solder balls generated around the welding spots in reflow soldering.

Description

technical field [0001] The invention relates to a flux, in particular to a flux used for SnAgCu alloy solder powder and a preparation method thereof. Background technique [0002] The traditional solder paste is mainly composed of lead-containing solder powder (such as lead-tin alloy solder powder). As a packaging material for electronic products, it has excellent welding and electrical conductivity for circuit boards that need to be welded, and the solder joints are bright. , full, but in the process of disposing of discarded electronic products (mostly using landfill treatment at present), the lead in solder powder encounters acid rain or acidic groundwater, it will seep into the ground, dissolve in groundwater, pollute the water source, people Drinking lead-contaminated water for a long time can lead to lead poisoning and cause serious harm to health. [0003] In view of the serious harm caused by lead solder powder, lead-free electronic packaging has become a trend arou...

Claims

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Application Information

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IPC IPC(8): B23K35/22B23K35/40
Inventor 周振基周博轩
Owner NICHE TECH KAISER SHANTOU
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