"Fingerprint" is a major scourge of PCB, and it is also one of the main causes of poor PCB scrapping and end user reliability degradation. And almost every aspect of PCB manufacturing runs through manual operations. Only every member of the manufacturing industry develops good habits, and the bare hand touch panel will reduce or cure the damage of fingerprints on PCB boards. PCB processing, hand and board contact opportunities are frequent, so fingerprints have become the most difficult problem in the industry. The following talk about the causes, hazards, and avoidance methods of fingerprints that can cause PCB defects:

1. Finger print: Finger print is hand sweat stain, its main components are as follows:

A, water

B, inorganic salts (such as Nacl, etc.)

C, fat oil (non-mineral)

D, cosmetics and skin care products

E, all kinds of dirt touched by bare hands (or dirty gloves)


2. The harm of fingerprints in the PCB manufacturing process

A. The bare touch plate chemically reacts copper on the surface of the plate in a very short period of time, resulting in oxidation of the copper surface. After a long time, it showed obvious fingerprints after electroplating, and uneven plating caused serious defects in the appearance of the product.

B. The bare hand touch plate before the solder mask will cause the soldering under the soldering, which will cause the adhesion of the green oil to deteriorate, and will foam and fall off when the hot air is leveled.

C. After the solder mask is removed from the soldering process until the pre-packaging process, the bare hand touches the board surface, which may result in the board surface being unclean, resulting in poor solderability or poor bonding.

D, printing wet film or silk screen and the surface of the film before the film with fingerprint grease, it is easy to cause the adhesion of the dry / wet film to decline, causing the plating and plating separation during plating, the gold plate is easy to cause the surface The pattern, after the completion of the solder mask production, the surface of the board is oxidized, and a yin-yang color appears.

If the above phenomenon is not standardized and eliminated, it will damage the qualified rate of the product, and the one-time pass rate will result in a long production and processing cycle, high rework rate and low on-time delivery rate, which will damage the image of the company in the customer's mind.