Gold electroplating technology process is widely used in various fields of national production, only by means of carefully operations to obtain effectively energy saving, protect the environment.A brief introduction of basic knowledge about the plating technology will be provided as following.Plating process category: Acid bright copper, Plating, Nickel/Gold electroless, Tin electroplating, Gold electroplating technology process…
Gold electroplating technical process:
Pickling → Entire board copper plating → Acidic degreasing → Microetching → Pickling → Tin plating → Pickling → Graphics copper electroplating → Nickle plating → Leaching citric acid→ Electrogilding
Gold electroplating technology process description of flows:
(1) Pickling:
① Function and purpose:
Removing the plate surface oxide, activated the plate surface, usually at a concentration of about 5% to 10%, mainly to prevent instability of sulfuric acid from bath water entering.
② Use C.P grade sulfuric acid, leaching time should not too long, to prevent oxidation of the board;
After a period of time, if the acid appears cloudy or copper content is too high shall replace in time, preventing plating copper cylinder and the plate surface pollution.
(2) Entire board copper plating:
① Function and purpose:
To protec thin chemical copper which is just deposited, to prevent etching from pickling, by means of plating to add to a certain of thickness.
② Entire board copper plating correponding parameters:
Bath solution main ingredients are copper sulfate and sulfuric acid, using high acid and low copper formulation, to ensure board surface uniformity and thickness distribution and deep plating ability for the deep hole;
Sulfuric acid content in more than 180 to 240g/liter;
Copper sulfate content is generally at 75g/liter, the bath solution may have trace amounts of chloride ions, as auxiliary brightener and copper light agent work together to get gloss effect;
Copper brightener additive amount at 3 ~ 5ml/L, the supplement generally in accordance with Kiloampere hours or actual effect board production;
Entire board plating current fomular is: 2A/dm multiplied by the area of the board can be plated;
Copper cylinder temperature control within 22 to 32℃.
③ Maintenance:
According to a Kiloampere hours to replenish copper brightener daily;
Check if the filter pump is working properly;
Using clean wet duster cloth to clean cathode conductive rod every 2-3 hours;
Weekly analyze and through Hall cell test regularly to adjust brightness agent levels and replenish in time;
Clean anode conductive rods, electrical connectors at both ends, replenish titanium anode copper ball in the basket weekly;
Titanium anode baskets bags should be checked for damaging and replace in time monthly, and check whether the titanium anode basket has accumulated anode mud;
Every six months in accordance with bath solution pullution condition to determine whether need large cleanning;
Every two weeks to replace the filter pump filter element.
④ Anode copper ball contains a small amount of phosphorus, the purpose is to reduce the efficiency of the anodic dissolution to reduce generation of copper powder.
⑤When suppling, if adding a large amount of copper sulfate or sulfuric acid, should be supplemented with a few slow steps, otherwise it will cause the bath temperature too high, brightness agents decomposition accelerated, and contaminate bath solution.
(3) Acidic degreasing:
① Function and purpose:
Remove the oxide of circuit coppoer surface, to ensure a bonding strength between copper panel plating with graphics copper electroplating or nickel.
② Adopt acidic degreasers, when under production only control concentration and time is enough.
(4) Microetching:
①Function and purpose:
Cleanning coarsening circuit copper surface, to make sure bonding strength between graphics copper plating with copper panel electroplating.
② Microetching agent using sodium persulfate.
(5) Pickling:
① Function and purpose:
Removing oxide of plate surface, to prevent instability of sulfuric acid from bath water entering.
② Use C.P grade sulfuric acid for pickling, leaching time should not too long, to prevent oxidation of the board.
(6) Graphics copper electroplating, also called as copper panel plating.
Function and purpose:
In order to meet the rated current of each line, each line plating and the aperture copper need to achieve a certain of thickness, line copper plating means to thicken the aperture copper and line plating to a certain thickness.
(7) Tin plating:
① Function and purpose:
Graphic pure tin plating purpose is to use pure tin as metal resist layer to protect the lines from etching.
② Bath solution mainly constituted by stannous mono-sulphate, sulfuric acid, and other additives;
The content of stannous mono-sulphate controlled within 35g/liter, while sulfuric acid about 10%;
Tin electroplating additive generally added in accordance with Kiloampere hours or supplemented according to the actual production of board;
The current calculation for tin plating typically ranges from 1.5A/dm multiplied by the board electroplating area;
Tin cylinder tank temperature should be maintained at room temperature, generally controlled at 22 to 30℃, so in the summer season due to high temperature, then cooling system shall be considered to install.
③ Maintenance:
Replenish tin additive agents according to kiloampere hours daily;
Check whether the filter pump is working properly;
Every 2 to 3 hours to clean cathode conductive rod with cleanning wet duster cloth;
Regularly analyze through the Hall cell test to adjust tin electroplating additive content weekly;
Clean anode conductive rods, electrical connectors at both ends;
Titanium anode baskets bags should be checked for damaging and replace in time monthly, and check whether the titanium anode basket has accumulated anode mud;
Every two weeks to replace the filter pump filter element.
④ Supplement medicines procedure as above, no details again.
(8) Nickle plating:
① Function and purpose:
Nickel plating mainly purpose as barrier layer between copper layer with gold layer, to prevent interpenetrate gold and copper, then impact board weldability working life;
Meanwhile bottoming with nickel layer will greatly increases the mechanical strength of the gold layer.
② Entire board copper plating process related parameters:
Nickel electroplating additives adding generally in accordance with kiloampere hours or based on actual board effective production, adding amount approximately as 200ml/KAH;
Graphics nickel plating current calculation general according to 2A/dm multiplied board electroplating area;
Nickel cylinder tank temperature maintained between 40 to 55℃.
③ Maintenance:
Replenish tin additive agents according to kiloampere hours daily;
Check whether the filter pump is working properly;
Every 2 to 3 hours to clean cathode conductive rod with cleanning wet duster cloth;
Regularly analyze through the Hall cell test to adjust tin electroplating additive content weekly;
Clean anode conductive rods, electrical connectors at both ends, replenish anode angle square in titanium basket, using low current for electrolysising of 6 to 8 hours;
Titanium anode baskets bags should be checked for damaging and replace in time monthly, and check whether the titanium anode basket has accumulated anode mud;
Every two weeks to replace the filter pump filter element.
④ Supplement medicines procedure as above, no details again.
(9) Electrogilding:
Divided into hard gold plating and water gold process, bath solution compositions basically the same, while hard gold bath has a few more trace metals nickel, cobalt, iron and other elements.
① Function and purpose:
Gold is a precious metal, has functions of weldability, oxidation resistance, corrosion resistance, small contact resistance, good wear characteristics alloy.
② PCB gold plating bath mainly as citric gold bath, simple maintenance, easy to operate.
③ Water gold content controlled in 1g/liter, pH value of about 4.5, temperature around 35℃.
④ The main additive as acid type adjustment salt, alkali type adjustment salt, conductive salt, gilded gold additives and other gold salt ect..
⑤ After plating gold plate should use pure water as water as recycling water, but can also be used to supplement the gold cylinder evaporation level changes.
⑥ Gold cylinder adopt platinum titanium mesh as the anode.
⑦ Gold syliner organic pollution gold shall use carbon core for continuous filtration, meanwhile adding the right amount of gold plating additives.
