Multilayer printed circuit board zedoary process control description
One, the purpose of the process description zedoary on printed circuit surface deposition is stable color, brightness is good, coating level off, good weldability of nickel and gold plating.
Basic can be divided into four stages: pretreatment (
In addition to oil, erosion, activation, after the baptism)
Sink sink, nickel, gold, post-treatment (
Waste liquid gold washing, DI water washing and drying)
Second, the former treatment before zedoary generally has the following steps: oil removal (
, the corrosion (
, the activation,
, after the baptism,
To remove copper oxide, and in the copper surface sink palladium, for heavy nickel activation center.
One link processes is not good, will affect the subsequent sink sink nickel and gold, and led to a mass of discarded.
Production process, various potions must regularly analysis and adding, control within the scope of the requirements.
More important, such as: micro corrosion rate should be controlled in '25 u -
40 u ', activate the potion must open the new cylinder when copper content is more than 800 PPM, medicine tank cleaning and maintenance of couplet of PCB quality impact is bigger also, in addition to the oil cylinder, micro erosion cylinders, leaching cylinder should be in cylinder, a week after the water washing cylinder should also be a weekly cleaning.
The main components of the three, sink sink nickel potion for Ni2 + (
8 g / 1)
And reducing agent sodium hypophosphite (
And stabilizer, the chemical nickel is strict with potion ingredients range, twice per shift in the process of production must be analyzed, and according to the production of plate area of bare copper or experience adding Ni2 reductant, when feeding, should follow a few, scattered the principle of filling material for many times, in order to prevent the local solution response, lead to the accelerated ageing of the plating solution, PH value, solution temperature on nickel thickness influence is bigger, nickel liquid temperature control in 85 ℃ - copy
PH in 5.
7, nickel cylinder when not in production, it should be nickel tank temperature down to about 70 ℃, were to slow the aging, chemical nickel plating solution is sensitive to impurities, a lot of harmful to chemical nickel, chemical composition can be divided into the following categories: inhibitors: including Pb.
Low melting point metal)
, organic impurities including S2, nitric acid and anionic wetting agent.
All of these material will reduce the activity, reduce speed of chemical plating and the plating leakage, severe punishment, causes a chemical nickel plating process to a full stop.
Organic impurities: including: besides the above mentioned organic stabilizer, and the plastic agent and from the equipment and the solder impurity.
Despite a range of impurities can be removed by continuous plating, but can not be completely removed.
Unstable agent: including Pd and small quantities of copper, the two components made in the chemical nickel is not stable, make coating roughness, and too much plating on the tank wall and heater.
Solid impurities, including calcium sulfate and calcium phosphate and other insoluble substances into or into the solution.
Filter to remove solid particles.
In short: in the process of production to take effective measures to reduce such impurities mixed with plating solution.
Four, zedoary zedoary process is a kind of gold leaching process, the main ingredient of zedoary cylinder;
Binder for (
16 mol / L)
, can replace on nickel phosphorus alloy layer out of pure gold plating, makes the coating is smooth and crystallization meticulous, solution PH value is in commonly 4 -
Between 5, control the temperature of 85 ℃
Five, the post-processing zedoary post-processing is also an important link, for printed circuit board, generally including: waste liquid gold washing, DI water washing, drying and other steps, conditional word can use level of heavy gold plate washing plate product further washing plate, drying.
Water washing machine can press liquid washing (
10% sulfuric acid, hydrogen peroxide, 30 g/L)
, high pressure DI water washing (
30 ~ 50 psi)
Order, DI water washing, blow dry, dry setting process, in order to completely remove the printed circuit board hole and surface potions and stain, and uniform coating can be obtained, brightness is good heavy gold plate.