Why can't PCB touch directly with fingers

　　Why can't PCB touch directly with fingers? What are the severe results if you touch the circuit board directly with your hands? In fact, it will lead to the bad cancellation of PCB board and the decrease of end-user reliability. However, in the process of operation, it is necessary to touch PCB board directly by hand, so it is necessary to develop the habit of wearing gloves, which can reduce the damage of direct contact to PCB board. Next, Yuwei Electronics will take us to understand the causes, damages and how to avoid the PCB defects caused by fingerprint printing.

1. Finger print: finger print is hand perspiration. Its main components include water, inorganic salts, fatty oils, cosmetics, skin care products and other pollutants.

　　2. Damage of finger printing during PCB manufacturing:

　　a. The bare hand contact plate before welding will lead to welding resistance, resulting in poor adhesion of green oil, which will bubble and fall in hot air;

　　b. In the process from solder stop to packaging, touching the board surface with bare hands will lead to unclean board surface and poor solderability or binding;

　　c. In a very short period of time, the copper on the board will react chemically when the bare object touches the board, which will cause the copper surface to oxidize. After plating for a long time, it has obvious fingerprint and uneven coating, which causes serious defects in product appearance;

　　d. There is fingerprint grease on the surface of wet film or screen printing line and before film pressing, which is easy to form dry / wet film adhesion reduction, which leads to separation of plating and plating during electroplating, and the metal plate is easy to form plate spot, which oxidizes the plate surface after completion of resistance welding, presenting Yin and Yang colors.

　　If the above phenomena are not eliminated, the qualified rate and one-time pass rate of damaged products will lead to long production and processing cycle, high rework and replenishment rate and low on-time delivery rate.

　　3. PCB circuit board, no bare touch board

　　a. Special gloves and finger covers should be carried with you;

　　b. To develop a good habit of taking and putting boards;

　　c. Gloves (such as cloth gloves, rubber gloves, finger sleeves, etc.) must be worn in the process of wearing gloves.

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