A kind of anti-pillow effect flux and its preparation method and application

Abstract

The invention discloses scaling powder capable of preventing the head-in-pillow effect and a preparation method and application thereof, and belongs to the technical field of solder. The scaling powder capable of preventing the head-in-pillow effect comprises, by weight percentage, 30-50% of unsaturated rosin resin, 20-50% of solvents, 5-20% of thixotropic agents and 1-10% of organic acid. The scaling powder preventing the head-in-pillow effect is prepared through the steps of crushing the unsaturated rosin resin, adding the crushed unsaturated rosin resin into the organic acid, and heating the mixture to 90 DEG C while stirring; adding the solvents into the mixture, naturally cooling the mixture to 80 DEG C after the solvents are dispersed uniformly, adding polyamide into the mixture, and heating the mixture while the polyamide is dispersed until the whole solution becomes transparent; and naturally cooling the mixture to 60 DEG C, then adding hydrogenated castor oil into the mixture, and cooling the mixture to obtain light yellow paste. After the scaling powder is mixed with lead-free tin powder to prepare soldering paste, the requirements of reflow soldering working conditions with long soaking and preheating time and high soaking and preheating temperature can be met, and good effects with good wetting property and bright welding spots and almost without tin sweats can be realized. The scaling powder has excellent performance of preventing the head-in-pillow effect.

Description

technical field [0001] The invention relates to the technical field of solder, in particular to an anti-pillow effect flux and its preparation method and application. Background technique [0002] The current surface assembly technology, that is, the SMT process, can be basically summarized into three steps: PCB printing solder paste, mounting components, and reflow oven soldering. Among them, due to the high temperature in the reflow soldering process, the existing BGA package components and PCB are prone to warping and deformation, resulting in the separation of BGA solder balls and solder paste printed on the PCB. There are two situations after the separation of the BGA solder ball and the solder paste. One is that the BGA solder ball at high temperature lacks the help of the flux in the solder paste, which makes it difficult to remove the oxide film on the surface of the solder ball; the other is that the BGA solder ball Before the ball and the solder paste are separate...

AI Technical Summary

Problems solved by technology

In the above two cases, during the cooling stage of reflow soldering, when the BGA chip and PCB are deformed or partially recovered, the BGA solder balls in the molten state and the molten solder paste regain contact, but due to the existence of the oxide film, the two cannot be fused together. Integral, after the soldering is completed, although the BGA solder ball and the solder paste are in contact, they are blocked by the oxide film, and no satisfactory solder joints are formed. This phenomenon is called the pillow effect (HIP)

The current solder paste technology only focuses on improving the deoxidation performance, but ignores the ability to prevent the secondary oxidation at high temperature after removing the oxide on the soldering point, so it does not have the ability to prevent the pillow effect.

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