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Lead-free soldering paste for fine distance of 0.25 mm and preparing method of lead-free soldering paste

A lead-free solder paste, fine-pitch technology, used in welding equipment, welding media, manufacturing tools, etc., can solve problems such as serious bridging and short-circuiting of components, and achieve excellent thermal slump resistance, good solderability, and contact. Excellent denaturation effect

Inactive Publication Date: 2018-04-17
XIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a lead-free solder paste for 0.25mm fine pitch, which solves the problem of serious bridging of existing solder paste under fine pitch technology, which causes short circuit of components

Method used

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  • Lead-free soldering paste for fine distance of 0.25 mm and preparing method of lead-free soldering paste
  • Lead-free soldering paste for fine distance of 0.25 mm and preparing method of lead-free soldering paste

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preparation example Construction

[0026] The preparation method of the above-mentioned 0.25mm fine-pitch lead-free solder paste, the specific steps are as follows:

[0027] Step 1: Weigh 35%-50% of rosin, 6%-12% of active agent, 6%-9% of thixotropic agent according to mass percentage, and the balance is solvent. The sum of the mass percentages of the above components is 100%, wherein , the rosin taken is a mixture of acrylic acid modified rosin and hydrogenated rosin;

[0028] Step 2: Add the solvent weighed in step 1 into the reaction vessel, heat to 125°C-135°C, add acrylic acid-modified rosin, and stir at constant temperature until the solution is uniform and transparent;

[0029] Step 3: Cool down the solution obtained in step 2 to 100°C-110°C, add the active agent weighed in step 1, and stir at constant temperature until the solution is uniform and transparent;

[0030] Step 4: Cool down the solution obtained in step 3 to 80°C-90°C, add the hydrogenated rosin weighed in step 1, and stir at a constant tem...

Embodiment 1

[0036] Heat 47% diethylene glycol monohexyl ether to 125°C-135°C, add 20% acrylic acid-modified rosin, and stir at constant temperature until it becomes transparent. Cool down to 100°C-110°C, add 8% azelaic acid and 4% sebacic acid, and stir at constant temperature until the solution is uniform and transparent. Cool down to 80°C-90°C, add 15% hydrogenated rosin, and stir until transparent. Cool down to 70°C-80°C, add 2% polyamide wax and 4% Thixatrol ST, and stir at constant temperature until the solution is uniform and transparent. Turn off the heat and continue stirring until the solution is a creamy flux. Mix 10% flux and 90% solder powder and stir evenly to get lead-free solder paste.

Embodiment 2

[0038] Heat 47% 1,2-propanediol to 125°C-135°C, add 20% acrylic acid modified rosin, and stir at constant temperature until transparent. Cool down to 100°C-110°C, add 6% sebacic acid and 6% salicylic acid, and stir at constant temperature until the solution is uniform and transparent. Cool down to 80°C-90°C, add 15% hydrogenated rosin, and stir until transparent. Cool down to 70°C-80°C, add 3% polyamide wax and 3% thixotropic agent 6500, and stir at constant temperature until the solution is uniform and transparent. Turn off the heat and continue stirring until the solution is a creamy flux. Mix 10.5% flux with 89.5% solder powder and stir evenly to obtain lead-free solder paste.

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Abstract

The invention discloses lead-free soldering paste for the fine distance of 0.25 mm. The lead-free soldering paste comprises, by mass percent, 88%-90% of soldering tin powder and 10%-12% of scaling powder, wherein the sum of the mass percents of the above components is 100%. The scaling powder comprises, by mass percent, 35%-50% of rosin, 6%-12% of an active agent, 6%-9% of a thixotropic agent andthe balance solvents, wherein the sum of the mass percents of the above components is 100%. The thixotropy is excellent, the printing manufacturability is good, viscosity is moderate, heat caving resistance is excellent, the welding performance is good, and the welding requirement for the fine distance of 0.25 mm can be met. The invention further discloses a preparing method of the above lead-freesoldering paste. Stirring is still conducted in the scaling powder cooling process, uniformity of the scaling powder and soldering paste is guaranteed, and meanwhile the viscosity of the scaling powder and the soldering paste is improved.

Description

technical field [0001] The invention belongs to the technical field of surface mounting of electronic circuits, and in particular relates to a lead-free solder paste for 0.25 mm fine pitch, and also relates to a preparation method of the above-mentioned lead-free solder paste for 0.25 mm fine pitch. Background technique [0002] With the rapid development and wide application of surface mount technology in the world, surface mount integrated circuit IC packaging components are also developing in the direction of high integration, high performance, multi-leads and narrow pitch. In actual production, the main rectangular Flat package component QFP also develops from 1.27mm center pitch to 0.65mm, 0.5mm, 0.4mm, 0.3mm fine pitch direction, which puts forward stricter requirements on the performance of solder paste in all aspects, so the preparation of fine pitch without Lead solder paste becomes a major task in the surface mount field. High-quality solder paste should have exce...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/26B23K35/40
CPCB23K35/262B23K35/40
Inventor 赵麦群杨楠朱孝培
Owner XIAN UNIV OF TECH
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