1. The concept

Cover a photosensitive solder ink on the PCB surface of the completed circuit.The ink can protect PCB circuit from oxidation and insulate the solder pad from welding unwanted circuit during welding

2. Inner layer mainly involves materials

1) finish copper clad PCB of the circuit

2) solder ink

3) silk screen

4) film

3. The process

1) purpose of pozzolana pre-treatment line: to clean PCB board by means of mechanical grinding brush and chemical cleaning, and to increase the binding force between solder ink and PCB board by roughening copper surface with pozzolana

2) purpose of screen printing machine: cover solder ink on PCB circuit board through screen printing screen

3) purpose of pre-baking: to preliminarily solidify the solder ink covered on PCB board, so as to facilitate CCD exposure and avoid ink contamination of film and CCD equipment

4) purpose of CCD exposure: through strong light irradiation, the photosensitized solder ink will undergo polymerization reaction, and the ink on PCB board will be solidified again, so that the welded pattern will not be transferred to the PCB board

5) development purpose: remove the solder ink needed to be welded and expose the welding pad

6) after baking: thoroughly solidify the ink on PCB board

4.The advantage

1) the minimum resistance bridge can achieve 3.5mil

2) the positioning accuracy of the welding pad window can be made to 0.8mil

3) minimum BGA window opening can achieve 8mil

4) plug hole capacity: 0.2mm-0.65mm;Plug full: > 85%

5) the maximum ink thickness can be produced to: 50um