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PCB solder mask technology for heavy copper thickness

The high in difference of heavy copper PCB is easy lead to oil float away,fake copper exposure,oil uneven when printed solder mask if controlled unwell.This article analysed and improved this problem through line mask printing area, solder mask opening of silkscreen ,printing lay up time and printing method.

The traditional process:

Pre-treatment—>solder mask printing—>lay up (2-3hrs)—>Pre-baking—>inspection—>exposure—>developing—>inspection—>solder mask oil solidifying—>Pre-treatment—>second solder mask printing—> lay up(2hrs)—>Pre-baking—>inspection—>exposure—>developing—>inspection—>solidifying

The shortcoming of traditional process:

  1. Oil wrinkle: as the difference in high is big lead to oil thickness is heavy between copper and base material, heavy oil is easy to wrinkle.
  2. Oil bubble: The air bubble is hard to squeeze out as heavy oil, produce oil bubble after pre-baking.
  3. Long time process: overlong lay up after printing is easy let oil moist and impact reliability.

solder mask

Technology and Reliability

Evaluated Technology: occured above questions as the big altitude difference,oil piled up too heavy, whether can squeeze out bubble at lay up process,reduce lay up time,we improved the technology process as below:

solder mask process

Through improved the process,we can save produce time 3-4hours.Put boards into vacuum machine and squeeze out air bubble can complete solve the solder mask bubble problem.

Quality is acceptable after vacuum squeezed bubble.

solder mask test

Through improvement of the process, it save produce time 3-4hrs and simplified process,improved quality,enhanced productivity,reduce cost,improved the delivery and competitive capacity.

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