Lead-free solder flux and solder paste

A lead-free solder and flux technology, applied in the direction of welding/cutting medium/material, welding medium, welding equipment, etc., can solve the problems of insufficient effect and low degree of freedom

Active Publication Date: 2007-12-19
ARAKAWA CHEM IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But its effect is not enough
There is also a problem that the degree of freedom in product design tends to decrease

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1～25 and comparative example 1

[0115] Examples 1 to 25 and Comparative Examples 1 to 4 (evaluation of bubble voids and solder balls)

[0116] (Preparation of Solder Paste)

[0117] Prepare flux with the raw material formula of Table 2~6, then, add Sn-Ag-Cu type solder metal powder (Sn96.5% by weight, Ag3% by weight, Cu0.5% by weight; trade name " Sn96 .5 / Ag3 / Cu0.5", manufactured by Mitsui Metal Mining Co., Ltd. (flux:solder metal powder = 1:9 weight ratio), kneaded for 1 hour with a planetary mill to prepare a solder paste.

[0118] (soldering (bump bonding))

[0119] The solder paste obtained above was printed on a test substrate for bump formation (substrate having a soldering surface at a pitch of 220 μm), and soldered by nitrogen gas reflow to obtain a test piece. The printing conditions were as follows. The bump diameter is about 100 μm.

[0120]

[0121] Metal template (mask): Laser processed product with a thickness of 70 μm

[0122] Metal scraping roller (squeege) speed: 20mm / sec

[0123] St...

Embodiment 26～30

[0157] Examples 26 to 30 (evaluation of voids and voids)

[0158] (Preparation of Solder Paste)

[0159] As the flux, what was prepared with the raw material formulation shown in Table 7 was used. In addition, the solder metal powder and the kneading machine are the same as above.

[0160] (Welding (direct bonding))

[0161] On a copper substrate for direct soldering (ceramic plate having a copper foil of 20 mm x 30 mm on the surface), use a screen mask and a squeegee roller for printing, and screen print the above-mentioned solder paste to a thickness of 0.15 mm, as test piece. The printing conditions are as follows.

[0162]

[0163] Preheating: 160~180℃, 80 seconds

[0164] Maximum temperature during reflow: 240°C, 220°C, about 30 seconds

[0165] (Observation of void holes)

[0166] X-rays were irradiated on the obtained test piece to visualize voids generated at the welded joint interface. Find the area of ​​the void hole (mm 2 ) and the area of ​​the plane elect...

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Abstract

A flux for a lead-free solder that is able to reduce "void(s) appear within solder joint", "void(s) appear within solder joint", and "solder-balling" without impairing general solderabilities. The flux for a lead-free solder comprising 6-55 wt% of a polyvalent alcohol ester of a resin acid (a1) as a base resin (A). Further, a solder paste comprising the said flux for a lead-free solder and a lead-free solder powder provides a very small number of void(s) or a very small amount thereof.

Description

technical field [0001] The present invention relates to a flux for lead-free solder (hereinafter, sometimes simply referred to as flux) and a solder paste containing the flux. Background technique [0002] In order to surface-mount electronic components such as capacitors on the wiring pattern on the circuit board, soldering is generally performed. Various characteristics are required for welding. For example, it is important to suppress the formation of "solder balls". Here, the term "solder ball" refers to a phenomenon in which solder paste printed on a conductor pattern excessively slumps and spreads during reflow heating and melting, and spherical fine solder appears near the edge of the slump. If the amount of solder balls is large, bridging and short circuits are likely to occur, and the reliability of the mounting substrate is significantly impaired. [0003] However, due to the reason that lead pollutes the environment and is harmful to the human body, in recent y...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/363B23K35/22H05K3/34B23K35/26C22C13/00
CPCB23K35/262B23K35/025H05K3/3484B22F2998/00B23K35/3612C22C13/00B23K35/3613H05K3/3485C22C1/0483B23K35/22B23K35/26B23K35/362H05K3/34
Inventor 石贺史男千叶安雄梶田和成
Owner ARAKAWA CHEM IND LTD
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