Reasons for damage or penetration dry film pcb board and its improvement
Jun 21, 2022
The wiring of the PCB board is very precise, and many PCB manufacturers use the dry film process to transfer the circuit pattern.
1. There is a hole in the dry film when the hole is masked
(1) Reduce the temperature and pressure of the film;
(2) Improve the roughness of the hole wall and the drape;
(3) Increase the energy of exposure;
(4) reduce the pressure of development;
(5) The time after filming should not be parked for too long, so as not to cause the semi-fluid film to diffuse and thin at the corners;
(6) When sticking the film, the dry film we use should not be stretched too tightly.
2. Infiltration plating occurs during dry film electroplating, indicating that the dry film and copper foil are not firmly adhered, so that the electroplating solution enters. The occurrence of seepage plating is caused by the following bad reasons:
(1) The temperature of the film is too high or too low
If the temperature is too low, the resist film will not be fully softened and flowed, resulting in poor adhesion between the dry film and the surface of the copper-clad laminate; if the temperature is too high, the solvent in the resist will volatilize rapidly to generate bubbles, and the dry film will become It is brittle, and it forms lift-off and peeling during electroplating electric shock, resulting in bleed plating.
(2) The film pressure is high or low
If the pressure is too low, the surface of the film will be uneven or there will be a gap between the dry film and the copper plate, which will not meet the requirements of the bonding force; if the pressure is too high, the solvent of the resist layer will evaporate too much, causing the dry film to become brittle, and it will become brittle after electroplating. Will lift off.
(3) The exposure energy is high or low
When the exposure is insufficient, due to incomplete polymerization, the film swells and softens during the development process, resulting in unclear lines or even the film layer falling off; Infiltration plating.
