Processing and pre-baking of multi-layer circuit boards involve the heating and drying of the liquid photoresist film surface. This aids in facilitating the exposure and development of patterns. It is crucial to follow certain precautions during this process to ensure successful outcomes. In this article, we will outline the recommended practices for pre-baking multi-layer circuit boards.
Precautions:

1. Use an oven with air blast and constant temperature control:

• This ensures uniform pre-baking temperatures across the PCB circuit board.
• The oven should be free of impurities to prevent any damage to the film surface.

1. Avoid natural drying and ensure complete drying:

• Natural drying may cause the film to stick and result in poor exposure.
• Ensure thorough and proper drying before proceeding with further steps.

1. Air-cool or naturally cool the board before negative exposure:

• After processing and pre-baking, allow the multi-layer circuit board to cool down before performing negative exposure.

1. Limit the shelf time after pre-baking:

• The time between pre-baking and developing the coating film should not exceed two days.
• In high humidity conditions, it is advisable to expose and develop the film within half a day.

1. Follow instructions for specific liquid photoresist:

• Different types of liquid photoresists have varying requirements.
• Carefully read the instructions and adjust process parameters such as thickness, temperature, and time accordingly.
  Temperature and Time Control:
• Correct temperature and time control during pre-baking is crucial for optimal results.
• Excessive temperature or prolonged time can make development difficult and film removal challenging.
• Insufficient temperature or inadequate time can result in incomplete drying, causing the film to stick and leading to poor exposure and potential damage.
  Conclusion:
  By following the proper processing and pre-baking techniques, multi-layered circuit boards can be developed swiftly and with high-quality graphics. As a well-respected FPC soft board manufacturer, WellCircuits Limited is committed to providing support to our customers. Please feel free to reach out to us with any queries or concerns.