Solution example for PCB circuit board acid copper fog

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Solution example for PCB circuit board acid copper fog

A factory circuit board acid copper fog solve examples


Copper tank old fog, MU and B agent excess possibility can be ruled out, the situation is much better after the big deal, but for two days there are fog phenomenon bright nickel can not be covered, and the longer the nickel plating white fog Obviously, had put copper-plated workpiece on the potassium dichromate in the wash, after activation in the nickel white fog can cover the low area on the coating but not bright, no light, Holocaust playing in the low zone Severe white fog, high brightness is poor, the effect of high temperature treatment is not obvious, and the overall plating is slow.

Discussion solution:

1, light agent disorders

A dose is too high

May be the proportion of light agent imbalance, with a small amount of activated carbon adsorption, or you continue to do two test pieces without light agent, the general consumption of A larger, hit the third piece of the test to see, is that How much less, plus hydrogen peroxide, activated carbon filter to the bath clean, and then warmed to 70 degrees above, electrolysis for several hours until the electrolysis coating evenly, the electrolysis can be the size of the current alternating, and then add the normal proportion of light Agent. General lack of chloride when the bright color will be dark.

2, add oil and sodium lauryl sulfate fully stirred plus toner filter clean

3, we all know, MN bright acid copper plating solution to be used, including chloride ions, including five to six brightener. When the proportion is proper, the coating has excellent brightness and flatness, and the high temperature characteristics of the bath is good. However, when the ratio is seriously imbalanced, the treatment requires some experience and simulation analysis means.

A factory has about 1200L of MN-type copper plating tank, due to the lower the brightness of the glitter and appear grit and pitting, technology and technicians, has added sulfuric acid and copper sulfate, little improvement; plus hydrogen peroxide, activity Carbon filter, without heat treatment, supplement the original use of good self-use brightener, the result is not bright coating, more serious sand.

I conducted the Hall groove test tank, were added to add a few brightener alone, the effect is acceptable, but added to the normal groove after a large tank or two soon after the marsh-like. After analysis, the Department of inadequate amount of activated carbon treatment, the selective adsorption caused a serious imbalance in the ratio, and after adding hydrogen peroxide without heating to remove the residue, so that additional additives and partially destroyed. According to conventional methods, should be combined with hydrogen peroxide, heating, after the complete destruction of additives with large doses of activated carbon adsorption, cooling and then press the formula to add brightener, but takes 3 to 4 days to complete (no refrigeration equipment, cooling than heating Difficult, no filter). The plant eager to complete the urgent processing, time is not allowed, only to find another way.

According to the nature of the oxidant, take 1 L plating solution for testing: adding metered potassium permanganate oxidized hydrogen peroxide, stirring, aerobic bubbles continue to produce. When no oxygen is generated, add about 0.2 g / L potassium permanganate and continue stirring for 10 minutes to oxidize the remaining brightener. Not filtered, take the liquid for Hall tank test, we can see that the brightener has been basically destroyed; according to the best ratio to re-add the new mixed brightener, and then through the Holzer test, the brightness of the basic recovery. Observed with a high power magnifying glass, the specimen is still a small amount of very fine sand, SP additional invalid, suspected chloride ion concentration is not enough, and then add 0.0001 ml / L of concentrated hydrochloric acid, all disappeared grit, brightness also increased, but still There are tiny protrusions, like crystal rough. Analysis of the reasons may be caused by excessive copper sulfate. Take out three tenths of the bath, add an equal amount of distilled water and a small amount of mixed brightener, the light leveling effect is good: 500 fine sandpaper polished copper specimen in the Hall tank stirred with 2 A plating 5 min, in addition to the low light about 1cm slightly worse, while the rest has reached a full bright mirror effect, high magnification observation, without any pit and protrusions. The three plating tanks were tested to determine the amount of each pot of potassium permanganate added, according to the test results after treatment, take liquid retest, and brightener ratio and then fine-tuning, the bath completely back to normal, and before the failure occurred Smooth leveling effect okay. Trough liquid test adjusted more than ten hours, that is, smooth processing of urgent pieces.

After this troubleshooting, I have the following experience:

(1) electroplating failure occurs, you should carefully observe the phenomenon of failure (the plant that the fault is rough coating, fine linen sand), high magnification microscope can be used to observe the coating (I had also encountered bright nickel as a result of excessive production of saccharin Fine numbness, the naked eye as a fog and manufacturers according to the causes of fog can not deal with the case). Bright copper plating, poor leveling and lack of brightness may be subtle pit, it may be subtle protrusions, if not accurate, the treatment is difficult to determine. The reason for the failure, mainly due to self-replenishment Brightener M more, after the accumulation of fine sand, plus SP can be resolved, but due to the judge not allowed to handle the improper handling of the plant’s shutdown.

(2) If the bright acid copper plating brightener imbalance difficult to adjust, it should be thoroughly treated, add enough hydrogen peroxide, activated carbon and heating to remove residual hydrogen peroxide. If you do not join the hydrogen peroxide after heating for activated carbon treatment, tank disorders will be more serious.

(3) dealing with bath failure, it is necessary to have practical experience, but also a certain chemical basis in order to handy. For example, no information has been reported with potassium permanganate acid copper plating solution, but according to chemical principles, potassium permanganate in acidic conditions than hydrogen peroxide strong oxidant, after adding without heating can be oxidized residual hydrogen peroxide and then oxidized Destruction of brightener, without activated carbon adsorption, filtration, that is, the emergency treatment of the bath (of course, its addition should be determined by careful testing) to meet the urgent need of production.

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