Table of Contents
Manufacturing processes of multilayer Printed Circuit Boards (PCB)
This page is dedicated to explaining the process flow of multilayer PCB manufacturing. The image gives an overview of this flow 1):
It is important to note that this flow is adapted depending on the type of PCB (single sided, double sided, or multilayer). See the image below to have a better understanding of the differences in process flows 2).
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0. substrate/board fabrication
1. board cutting
| Process steps | Process description | Inputs | Outputs |
|---|---|---|---|
| sharp edge removal | soften the edges of the board | CCL sheet (copper sheets + glass fiber impregnated by resin), energy for equipment functionning | |
| cutting | cut the CCL sheet to the required size |
2. inner layer printing and etching
2.1 pre-treating
| Process steps | Process description | Inputs | Outputs |
|---|---|---|---|
| cleaning | remove impurities and increase copper roughness | ||
| drying | blow dry |
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2.2. dry photosensitive film lamination
applying the resist film on the pane l
2.3. UV ray exposure
exposing the photosensitive film to UV rays in a dust-free brown lighted room using a photomask
2.4. developpment
removing unexposed photosensitive film
2.5. etching
removing the unwanted copper around parts protected by the photosensitive film
2.6. stripping
removing remaining photosentsitive film parts
3. optical inspection
checking the conformity of the internal layer traces with the virtual design using optical system
4. lamination
| Process steps | Process description | Inputs | Outputs |
|---|---|---|---|
| oxidating | roughing and passivating copper | ||
| stacking up | stack up core layers together, copper foil and pre-preg | ||
| laminating | laminating all layers together | ||
| cooling |
- oxidating: roughing and passivating copper
- stacking up: stack up core layers together, copper foil and pre-preg
- laminating: laminating all layers together
- cooling
- drilling position checking: checking drilling position to avoid misalignment
- edge routing: removing resin or copper foil that sticks out the board
- edge milling: remove rough edges
- visual checking
5. drilling
- drilling a location hole: drilling a hole to fix the board for further drilling and ensure allignment
- inserting pins: pins to maintain boards together
- drilling holes
- inspection: checking the alignment and the correct position of holes
6. electroless copper deposition
- cleaning: successive steps to remove dust, smear from drilling, etc.
- etching: pepare the surface for plating by modifying its surface properties
- activation: immersing the surface in catalyst colloid to attach it to the surface sites
Discussion