The first step in the inner layer PCB manufacturing process begins with large copper-clad laminates. Since the original panels are typically oversized, they must first be cut into appropriate working dimensions according to production requirements using a cutting machine. Following cutting, the panels undergo pre-treatment, a critical process designed to ensure that the copper surface is clean, roughened, and uniform. Pre-treatment generally consists of three main stages: mechanical brushing, chemical cleaning, and high-pressure dust removal.

• Mechanical brushing removes the oxide layer and increases surface roughness.
• Chemical cleaning eliminates oil, fingerprints, or other contaminants.
• Dust removal ensures that fine particles are completely cleared from the surface.

These treatments are essential for ensuring proper adhesion of the dry film photoresist and maintaining the precision of subsequent circuit patterns. Poor surface preparation may lead to defects such as photoresist peeling, short circuits, or incomplete circuitry during the exposure and etching stages. Although pre-treatment may appear simple, it is in fact a key determinant of product quality and a vital part of the entire PCB fabrication process.

FAQ

What is panel cutting in PCB manufacturing?

Panel cutting is the process of cutting large PCB laminate sheets into smaller production panels suitable for inner layer fabrication and subsequent PCB processing steps.

Why is pre-treatment important before the inner layer process?
Pre-treatment removes oxidation, dust, oil, and contaminants from the copper surface to improve dry film adhesion and ensure accurate circuit imaging.

What does micro-etching do during PCB pre-treatment?
Micro-etching slightly roughens the copper surface to enhance bonding between the copper layer and the dry film photoresist used in imaging.

What problems can occur without proper pre-treatment?
Improper pre-treatment can cause poor dry film adhesion, uneven etching, open or short circuits, and reduced PCB reliability.

What process comes after panel cutting and pre-treatment?
After pre-treatment, the PCB proceeds to dry film lamination, UV exposure, developing, and etching to create the inner layer circuit patterns.