Technical | Electrolytic Copper Foil Common Problems Solutions

2024-01-16

Question I

Excessive copper foil pinholes penetration points

Formation
Causes

(1) The cleanliness of the electrolyte exceeds the stard, there are contaminants such as oil glue;
(2) Air holes or inclusions on the cathode surface;
(3) Dirt adhering to the cathode surface;
(4) Severe copper powder on the glossy surface.

Processing
measures

(1) Enhance filtration;
(2) Replacement of filter cartridges or filter bags;
(3) Add or replace activated carbon;
(4) Replace the cathode roller or grinding roller.

Question two

Craters scratches

Reasons for formation

(1) When unpeeling, copper particles enter between the stripper roll the copper foil, resulting in indentation, if they enter between the idler roll (the guide roll that is supposed to rotate but does not) the copper foil, resulting in scratches.
(2) Copper particles enter the surface of the attached copper foil during unpeeling get caught in the copper foil rolls, resulting in indentation of the copper foil.
(3) The foreign debris produces indentations scratches, mainly large dust in the air, s dust dropped by the vibration of the traveling car above the foil making machine.

cure

(1) For dry craters scratches, only use a dry towel or brush to clean the guide rollers that created the craters or scratches. During the high failure period, it is recommended to clean up every 5 minutes.
(2) Technically, the guide rollers in contact with the copper foil should be rotated as much as possible through technological modification to eliminate the phenomenon of idler rollers minimize the defects of scratches.

Question three

aberration

Formation
Causes

By chromatic aberration, we mean that the color of the foil surface is not consistent. Spots, color bs, color strips, etc. can lead to color differences on the foil surface. The reasons for the production of color difference are quite complex mainly lie in:
(1) Incomplete acid washing water washing before (after) stripping the raw foil from the surface of cathode roll;
(2) Inappropriate gap of pressurized water roller of raw foil machine;
(3) Severe acid mist on site, resulting in a large number of acid mist spots on the foil surface;
(4) Oxidation of cathode roller surface;
(5) Incomplete drying of raw foil, oxidization of raw foil surface;
(6) Anode damage;
(7) The amount of washing water is on the small side the electrolyte is not rinsed out, resulting in crystallization of electrolyte on the foil surface;
(8) The washing water is contaminated, dirt, oil etching, corrosive substances, salts, grease, etc. may lead to color difference on the foil surface;
(9) Mercury contamination. For companies that use mercury to conduct electricity, a large number of mercury points, is also a major cause of color difference on the surface of copper foil.

Processing
measures

The causes of color difference should be analyzed targeted measures should be taken. For example, if there is a regular brown color b on the gross surface of the raw foil, it may be that there is a gap in the pressurized water roller of the raw foil machine, resulting in the rinsing water entering the electrolyte, the pressurized water clip should be overhauled adjusted.

Question four

fatigue ductility

Reasons for formation

The low concentration of CI ions in acid sulfate copper plating solution not only serves as a depolarizing agent leveling agent, which is beneficial for obtaining better ductility; but also strengthens the crystallographic optimum weave, causing a reduction in ductility. On the other h, too high a concentration of CI ions can lead to the formation of pinholes in the copper coating, resulting in a significant reduction in the ductility of the coating.

cure

In the actual production, if you find that the copper foil at room temperature 180 ℃ when the elongation fatigue ductility problems, according to the above analysis, first of all, we should check whether the CI concentration of the electrolyte of the foil machine is over the stard; the second is to check the organic impurities in the electrolyte; if it is over the stard, it can be used to adsorption filtration of activated charcoal; then check the additives, Cu, H2SO4, temperature flow rate.

Question five

Copper Foil Tear Edge

Formation
Causes

(1) When the copper foil is stripped from the surface of the cathode roller, it is caused by excessive bonding force with the edge of the cathode roller. On the one h, since the cathode roller is electrically immersed in the electrolyte as a whole, it is inevitable that an electrolytic copper layer will be deposited on the end of the roller, which makes it difficult to peel off the copper foil at the edge of the roller surface.
(2) On the other h, the cathode roller's edge polishing is not good, the roller surface end right angle damage, end surface grinding finish is low will also cause the cathode roller roller edge of copper foil bonding force is too large.

Processing
measures

(1) In order to solve the problem of copper layer deposited on the side of cathode roller, generally sealing the end of cathode roller is adopted to reduce copper deposition by not letting electrolyte contact the end of roller.
(2) The sealing of cathode roller end seems to be a small matter, but in fact it is a big problem related to whether the production can be carried out normally. Sealing is not good, the electrolyte can enter the cathode roller end surface through the gap, where electrolytic deposition, due to the tip discharge effect, the formation of loose copper particles on the edge of the copper foil (also known as copper beans).
(3) As the copper particles are much larger than the thickness of the copper foil, the adhesion is perpendicular to the peeling force of the copper foil, as a nail in pinning the copper foil to the cathode roller surface. When the copper foil is peeled off from the cathode clip, if the strength of the copper foil itself is smaller than the adhesion of the copper beans on the cathode roll, the copper foil will tear from the vicinity of the copper beans, producing the phenomenon of edge tearing. If the copper bean is smaller or the adhesion of the copper bean on the cathode roller is smaller than the strength of the copper foil itself, when stripping, the copper bean will be brought down from the cathode roller by the copper foil to form a burr, the burr (copper bean) will fall on the copper foil to cause pressure pits pressure eyes. Larger copper beans are brought down, if they fall into the anode slot between the poles, they will cause electric shock rollers.

Question six

Mass per unit area (basis weight) deviation

Reasons for formation

(1) Calculation error;
(2) Severe damage or deformation of the anode.

cure

(1) For DSA titanium anode, if the coating partly falls off, it will lead to small quality of thin copper foil area in the cathode part corresponding to the part that falls off; in the case of lead anode, due to the deformation, bulging occurs in the individual position, which will lead to the cathode anode distance becoming smaller, the current increasing, the thickness of copper foil increasing. Partial damage to the titanium anode can be temporarily solved by shielding the anode, but fundamentally the anode must be replaced; deformation of the lead anode, generally online for manual correction, in serious cases, the anode needs to be removed corrected by special equipment.

(2) Individual rectifier cabinet jumping. Due to the current high-current electrolysis, generally 2-4 rectifier units are used to supply power, each rectifier unit provides a current of 12500A. One of the rectifier unit can not work the operator did not find in time, can also lead to the copper foil area quality deviation.

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