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Multilayer PCB Oxide Treatment
Jul 27, 2017

Multilayer PCB Oxide Treatment


The effect of oxide treatment: passivation of the copper surface; to enhance the surface roughness of copper foil, and enhance the epoxy resin and the inner layer of copper between the binding force for multilayer PCB.


General inner layer of black oxidation method:

 Brown oxidation method

 Black oxidation treatment

 Low temperature black oxidation method

The use of high temperature blackening of the inner layer will produce high temperature stress (thermal stress) may lead to laminated after the separation of the interlayer or copper foil cracks;


Brown oxidation:

The product of the black oxidation treatment is mainly copper oxide, there is no so-called cuprous oxide, which is the industry's some misconceptions, after ESCA (electro specific chemical analysis) analysis, can be measured between copper atoms and oxygen atoms between the binding energy, oxide The ratio between copper atoms and oxygen atoms on the surface; clear data and observations show that the product of blacking is copper oxide, no other ingredients;

The general composition of blackening liquid:

Oxidizer sodium chlorite

 Sodium hydroxide

 PH buffer trisodium phosphate

 Surfactant

 Or aqueous solution of basic copper carbonate (25% aqueous ammonia)


The relevant data

1, the oxide weight; can be measured by weight, generally after the control in the 0.2 --- 0.5mg / cm2

2, peel strength 1oz copper foil in accordance with the speed of 2mm / min, copper 1/8 inches wide, the tension should be 5 pounds / inch or more

3, through the relevant variable analysis affect the tear strength of the significant factors are:

1. the concentration of sodium chlorite

2. the concentration of sodium hydroxide

3. the interaction of sodium chlorite and trisodium phosphate concentration

4. the interaction between trisodium phosphate and immersion time

The length of the needle-like crystals of the oxide is preferably 0.05 mil (1-1.5 um), and the tear strength at this time is also large;

The tear strength depends on the fillability of the resin to the oxide crystal structure and is therefore related to the relevant parameters of the laminate and the properties of the resin pp.