Dry film production of circuit boards in the process of a few common errors and improve it

With the rapid development of the electronics industry, PCB wiring is becoming more and more sophisticated, most PCB manufacturers are using dry film to complete the graphic transfer, the use of dry film is becoming more and more popular, but I'm in the process of after-sales service, I still encountered a lot of customers in the use of dry film produces a lot of misunderstandings, which is now summarized in order to learn from.

一、 the dry film mask hole appears broken hole

Many customers believe that, after the emergence of broken holes, should increase the temperature and pressure of the film, in order to enhance its bonding force, in fact, this view is incorrect, because the temperature and pressure is too high, the resist layer of solvent excessive volatilization, so that the dry film becomes brittle and thin, development is very easy to be punched through the hole, we always want to maintain the toughness of the dry film, so, after the emergence of broken holes, we can do to improve the following points:

1, reduce the film temperature and pressure

2、Improve the drilling phi

3, improve the exposure energy

4, reduce the development pressure

5, after the film can not be too long to park, so as not to lead to the corner parts of the semi-fluid film in the pressure of the role of diffusion of thinning

6, the process of laminating the dry film should not be spread too tightly

二、the dry film plating seepage plating

The reason why seepage plating, explaining the dry film and copper-clad plate bonding is not firm, so that the plating solution in-depth, resulting in the "negative phase" part of the plating layer becomes thicker, the majority of PCB manufacturers seepage plating is caused by the following points:

1, high or low exposure energy

Under ultraviolet light irradiation, absorbed light energy photoinitiator decomposition into free radicals to trigger the monomer photopolymerization reaction, the formation of insoluble in dilute alkali solution of the body type molecules. Insufficient exposure, due to the polymerization is not complete, in the development process, the adhesive film dissolves and softens, resulting in unclear lines or even film layer off, resulting in poor combination of film and copper; if the exposure is too much, it will cause difficulty in developing, but also in the plating process to produce warping peeling, the formation of osmosis plating. So it is important to control the exposure energy.

2, the film temperature is high or low

If the film temperature is too low, the resist film does not get sufficient softening and proper flow, resulting in poor bonding between the dry film and the surface of the copper-clad laminate; if the temperature is too high due to the rapid evaporation of solvents and other volatile substances in the resist to produce bubbles, and the dry film becomes brittle, the formation of warping peeling in the plating process, resulting in plating penetration.

3, the film pressure is high or low

Lamination pressure is too low, may cause uneven film surface or dry film and copper plate gap between the requirements of the bonding force can not be achieved; film pressure if too high, the resist layer of solvents and volatile components too much volatilization, resulting in the dry film becomes brittle, plating will be warped peeling after electric shock.