In-depth analysis of the SMT chip processing on the tin is not full of glossy enough reasons?

In the precision hall of SMT SMD production, the tin process undoubtedly plays a pivotal role, and its degree of perfection is directly related to the final quality of the product and customer satisfaction. However, the tin is not full of this defect, as a delicate brocade on a flaw, although small but can not be ignored. Suzhou Neufeld, as a leader in the industry, hereby analyze the causes behind this phenomenon in depth, in order to provide valuable reference for colleagues in the industry and reference.

First, the following six is not full of tin on the main reason:

Solder paste wetting performance of the short board: If the solder paste in the flux paste body fails to achieve the ideal wetting standards, it is as dry as the brush, it is difficult to draw on the fullness of the solder solder soldering point.

Flux activity is not enough: the lack of flux activity, like a weak cleaning agent, it is difficult to completely remove the oxidized layer on the pad, thus laying a hidden danger for the tin road.

Flux surface tension shackles: excessive surface tension, like a taut string, easy to form a hole in the soldering process, affecting the fullness of the solder joints and aesthetic.

Oxidation challenge of pad and SMD: Oxidation of the pad or SMD soldering parts, like the traces of time, silently

Erode the perfection of the soldering, resulting in poor tin effect.

Insufficient amount of solder paste is too little: Without using enough solder paste, excellent soldering quality cannot be guaranteed, and it is naturally difficult to obtain full solder joints.

Uneven mixing defects: the mixing of solder paste before use is a key step in the fusion of flux and tin powder. If this link is negligent, will lead to solder joints are not full, leaving regrets.

Second, the solder joints lack of gloss of the five major mysteries

Tin powder oxidation erosion: tin powder oxidation, as the years of frost, quietly reduce the gloss of the solder joints, so that PCBA eclipsed.

Additive matte effect: some additives in the solder paste, although it has its own use, but also brings the worry of matte, affecting the glossy performance of the solder joints.

Insufficient preheating temperature: If the preheating temperature of reflow soldering is not up to the standard, it will leave behind non-evaporable material, which becomes the culprit of the lack of solder joint gloss.

Residue interference: no-clean solder paste is convenient, but its residue may become a stumbling block to the gloss of the solder joints, need to be carefully selected.

No clear standard dilemma: the lack of uniform standards for solder joint gloss, so that the gloss of different solder paste products between the differences, it is difficult to generalize.

Third, the way to prevent the problem of soldering

Void soldering, this hidden blunder, often lurking in the circuit board, on the irregularities that will occur from time to time. In order to avoid such anomalies, we need to start from the judgment and resolve the two aspects:

Judgment method:

Utilize in-line testers and other specialized equipment for accurate inspection.

Through visual or AOI inspection, to capture the solder joints in the subtle abnormalities, such as too little solder, poor wetting and so on.

Solution strategy:

Timely replenish the amount of solder paste reduced by scratching.

Optimize PCB design to avoid loss of solder and mismatch of spacing and area caused by through holes.

Thoroughly remove the oxidized layer on the circuit board, oil stains, sweat stains and other pollutants to ensure that the welding surface is clean and dry.

In summary, SMT SMD processing on the tin and solder spot gloss issues, we need to be rigorous attitude, professional knowledge to face and solve. Only in this way, we can ensure that each solder joint is as bright as a star, for the escort of product quality.