First we need to select materials, baking pretreatment, in order to prevent the contraction of the material deformation to the process after the trouble.
2. The diameter of blanking carbon hole for double sided flexible PCB
The blanking carbon hole is generally 0. 8 to 1. 0 mm. Pay attention to the carbon hole must be selected properly, the hole is too large, in the screen printing lower line, through the carbon hole infiltration of carbon ink too much, excess ink will flow through the carbon hole remains in the screen printing table, easy to cause the short circuit of the line.
3. Double sided flexible PCB bottom line screen printing
Take the locating hole as the datum, prints the lower layer line in the non-screen printing surface. In the process of screen printing, if the use of machine printing, the table using vacuum suction device is conducive to the flow of conductive ink, but often easy to make ink residue on the table, residual ink must be removed in a timely manner, otherwise it will affect the quality and beauty of the line, or even cause a circuit short circuit. If manual printing is used, the table does not have vacuum suction device. After screen printing, the circuit board should be placed for a period of time before drying in the drying oven, so that the conductive ink can flow fully and the two-layer circuit can be conducted. Screen printing process to control the thickness of the ink to meet the line resistance value requirements.
4. Appearance stamping and final product inspection
According to the purpose of the circuit board, the stamping forms an appearance with certain size requirements. Test whether the circuit is short circuit, open circuit and resistance value meets the requirements.