Following up on the last news, this news article continues to learn the acceptance criteria for the quality of PCB solder mask process.
Surface Treatment Requirements:
1. The ink surface must not have any accumulation, wrinkling, or cracking of the ink.
2. No bubbling of the ink or poor adhesion (must pass the 3M tape test).
3. No obvious exposure imprints (stains) on the ink surface. Inconspicuous imprints are allowed on no more than 5% of the board area per side.
4. No exposed copper on both sides of parallel lines. No obvious ink unevenness is allowed.
5. The ink surface must not be scratched to expose copper, and no finger prints or missing prints are allowed.
6. Ink smudging: The length and width must not exceed a range of 5mm x 0.5mm.
7. It is permissible for the ink colors on both sides to be inconsistent.
8. If the surface-mounted pad spacing is greater than 10mil and the green oil bridge width (by design) is greater than 4.0mil, green oil bridge breakage is not allowed. If the solder resist process cannot meet the above requirements due to abnormalities, the following is acceptable: the number of green oil bridge breaks per row is within 9%.
9. The diameter of star-shaped exposed copper spots should be less than 0.1mm, with no more than 2 spots per side. No batch positioning points should have exposed copper
10. The surface must not have obvious screen printing or ink debris particles.
Gold Finger Design Requirements:
1. No ink should be applied on the gold fingers.
2. No residual green oil should be left between the gold fingers after development.
More acceptance criteria will show in the next news.
