Brown Oxide and Black Oxide in PCB Production

In the production process of multi - layer PCB boards, after completing the inner - layer dry film and conducting line inspection, Brown Oxide or Black Oxide treatment is carried out immediately. Black Oxide is derived from Brown Oxide.

Functions of Brown Oxide

Core Purpose: Enhance the bonding force between the original board and PP (prepreg), which is the key to ensuring the quality of the PCB board.

Specific Functions:

lRemove grease and debris on the surface of the original board to ensure a clean board surface, laying a good foundation for subsequent processes.

lForm a uniform layer of fluff on the copper surface of the substrate, further improving the bonding force with PP and preventing delamination and board explosion.

lAfter Brown Oxide treatment, lamination must be done within the specified time to prevent the Brown Oxide layer from absorbing water, thus avoiding affecting the performance of the PCB board.

Process Advantages: 

lThe process is simple, easy to control, and convenient for actual production operations.

lThe Brown Oxide film has good acid resistance and no pink - ring defect, ensuring stable product quality.

lUnder allowable process conditions, it has a cost advantage and is an economical choice.

Black Oxide

Black Oxide is to roughen the copper surface. The aim is to maintain strong adhesion after the copper surface of the multi - layer board and the resin P - sheet are laminated. With the change of demands, roughening treatment has also derived Brown Oxide, Red Oxide, and Brass Oxide treatments.

Common black - oxidation methods for inner - layer treatment include the Brown Oxidation method, Black Oxidation treatment, and Low - temperature Blackening method. It should be noted that the High - temperature Blackening method can cause high - temperature stress on the inner - layer board, which may lead to inter - layer separation or cracks in the inner - layer copper foil after lamination.

Differences between Brown Oxide and Black Oxide

lFluff Thickness: The fluff produced by Black Oxide is thicker than that of Brown Oxide.

lChemical Solution Management: The difficulty of storing, using, and regulating the Black Oxide chemical solution is higher than that of the Brown Oxide chemical solution.

lChemical Solution Price: The price of the Black Oxide chemical solution is significantly higher than that of the Brown Oxide chemical solution.

lMicro - Etching Rate: The micro - etching rate of the Black Oxide chemical solution is greater than that of the Brown Oxide chemical solution.

lQuality Performance: The surface roughness of the circuit board after Black Oxide treatment is large. For minor scratches and wire repairs on the inner - layer circuits, the covering effect of Black Oxide is better than that of Brown Oxide.

Similarities between Brown Oxide and Black Oxide

lEnhanced Bonding Force: Increase the contact area between the copper foil and the resin, strengthen the bond, and stabilize the structure of the PCB board.

lImproved Wettability: Improve the wettability of the copper surface to the flowing resin, enabling the resin to flow into dead corners. After hardening, the adhesion is stronger, ensuring the quality of the PCB board. 

lPassivation Formation: Form a fine passivation layer on the copper surface to prevent the hardener from reacting with copper under high temperature and high pressure to produce water, avoiding board explosion and improving the reliability of the PCB board.

PCBMASTER (pcbmaster.com) always adheres to the persistent pursuit of quality, continuously innovates process technologies, and strictly controls every production link. We are committed to providing customers with high - quality and high - performance PCB products to meet the diverse needs of different industries and fields.