Why Silkscreen is essential for PCBA production
What is silkscreen?
In automated electronic assembly applications, silkscreens are alignment marks used in indexing systems to orient the PCB in the correct direction and skew. Vision systems use silkscreen placement to precisely insert components into circuits. Silkscreen, also known as "Circuit Pattern Identification Marking", is a critical aspect throughout testing and packaging throughout the automated manufacturing process. The importance of silkscreen placement cannot be underestimated because if at any point during the assembly process the exact location of the board or circuit cannot be measured correctly, there will be an automation "train wreck"!
How does the placement of the silkscreen affect the insertion of components?
Precise silkscreen placement ensures your PCB is oriented in the correct direction and aligned as close to perfect as possible. The SMT placement machine uses a camera to position the silkscreen and then adjusts the position of the components according to the exact position of the board.
The PCB is fed to the SMT machine for assembly from the conveyor. Each PCB is held or clamped in a slightly different orientation than the others, and this small change is enough to destroy the board unless it is recalibrated. For this purpose, two or three fiducials are marked on the PCB so that the placement robot can precisely orient the board. By comparing the actual position of the silkscreen relative to the board plan stored in the machine's memory, the vision system can reliably calculate the "offset" the part must move to in order to place it accurately.
Before we let suppliers make PCB boards, our BQC will confirm the silk screen layer with customers, and let customers provide silk screen pictures to ensure the smooth production of subsequent PCBA component placement.
