Plating relevant functions

car electroplating

Plating relevant functions–make use of electrolysis to deposit of good adhesion of the article , but the performance of different materials and the base metal cladding techniques . Than the hot-dip plating layer having a uniform , generally thin, ranging from a few microns to tens of microns . By electroplating , you can get protective and decorative surface layer on the various functions of mechanical products , you can also repair wear and workpiece machining errors .

Moreover , there are different plating relevant functions according to the needs of variety of plating.

For example:
1, Copper plating: bottoming to enhance the plating layer adhesion, and corrosion resistance. ( Copper is easily oxidized, after oxidization, patina is no longer conductive, so copper electroplating products must be done copper plating protection.
2, Nickel electroplating: bottoming or for appearance to enhance corrosion resistance and wear ability, ( which is the modern process wear- ability more over than chrome plating) are no longer use nickel bottoming, mainly due to the nickel magnetic, which will affect the electrical performance of passive intermodulation.
3, Gold-plated: improving conductive contact resistance and enhance signal transmission. ( Gold is the most stable, but also the most expensive material. )
4, Palladium Nickel plating: improving conductive contact resistance, and enhance signal transmission, abrasion resistance is higher than gold.
5, Plating tin-lead: the ability to enhance welding, soon to be replaced by other alternative materials ( now mostly replaced by lead- tin -plated bright and matte tin).
6, Silver plating: to improve the conductive contact resistance and enhance signal transmission. (Silver has the best performance, but easily to be oxidized, and still can conduct after oxide).Electroplating is a method which using the principle electrolytic to cover a metal layer on conductive.

In addition to the conductive, plating also can be used for plastic cement after special handling.

The basic process of electroplating as follows:

Connected the plating metal  on anode, while the be plated metal connected on cathode.
Connection between anode and cathode by connection by electrolyte solution composed by metal positive inos. Powered by DC current, the anode metal will be oxidized (loss of electrons), while positive ions in solution will reduction in cathode ( to obtain electron) and become atomic and accumulate on cathode surface.
After electroplating, the to be plated workpiece appearance related to current size, the smaller the current, the workpiece will be more beautiful appearance; otherwise it will appear a number of uneven shapes.
The main purpose of plating mainly including preventing of metal oxide ( e.g rust ) as well as decoration. The outer layer of coin is also a plating .
Waste water in plating process  (e.g ineffective electrolyte) is the biges source of water pollution.

Plating technology process has been widely used in the semiconductor and microelectronics technology components of the lead frame.
VCP: vertical continuous plating, the new machine which circuit boards adopted is more better quality than traditional hanging plating.

Partially silver electroplating:

Aluminum plating solution formulation process:

High-temperature acid weak base etching → Rinse →Acid picking ​​→ Rinse→ Zincate →Rinse → Second zincating→ Rinse → Pre copper plating → Rinse → Rinse → ​​Cyanide silver plating ​​→ Recycling rinse→ Rinse → Brightness dipping → Rinse → ​​drying.
From the plating process we can tell, the material must be high temperature resistance ( about 80 ℃), alkali resisting, acid resisting, secondary, the protective material can be easily peeled off after the silver plating.

Electroplating fundamental concept

Electro plating Fundamental conceptFundamental concept:

When under plating, coating layer or other insoluble material called as anode, workpiece to be plated called as cathode, the plating layer metal’s anode to be restored to form electroplating layer on workpiece. To exclude the interference of other anode, and to make sure coating layer uniformity, strong, should use plating solution which with plating layer metal anodes, in order to maintain constant layer anode concentration. The purpose of plating is to plate metal layer on base material to change base material plate property and size. Plating can enhance metal corrosion resistance (plating layer most adpot corrosion resistant metal), increase hardness, abrasion prevention,  and can improve conductivity, lubricity, heat resistance and surface appearance.

Electrolating

electroplating

Electroplating:

Electroplating is to make usage of electrolytic principle to plate a thin layer of metal or alloy on some kinds of metals’ surface, which is a technology by means of electrolytic action to adhese metal file on metals or other material surface, in order to prevent metal oxides (eg rust), improve abrasion resistance, electrical conductivity, reflectivity and enhance aesthetic effects. Many coin outer layer are plated.

Gold electroplating technology process

Gold electroplating technology process

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 plating

Gold plating

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.

Hard chrome machine plating process procedures

A, Plating processes introduction:

Hard chrome machine plating process procedures is a technology that coat a thick plating layer in a variety of matrix surfaces, its thickness generally more than 20μm , which making the use of chrome characteristic to improve parts performance of hardness, wear resistance , heat and corrosion resistance and other properties.

Hard chrome plating technological characteristics:

1)  Cathode current efficiency as high as 50 % to 65% , and the deposition rate very quickly;
2)  Coating layer hardness as (900 ~ 1200 HV), appear to homogeneously dense network cracks, has feature of good wear resistance;
3)  Electroplating solution dispersing ability good, coating thickness uniformity, and not easy to produce rough blister aneurysm phenomenon, which the plating layer appearance looks bright and green;
4)  The binding force between coating layer and the substrate is strong, and compare with traditional process, the pre-treatment similar and operating easier than the traditional process;
5)  Trivalent chromium content allowed tolerance in plating solution is wide, usually do not require discontinuation electrolysis to treatment trivalent chromium;
6)  Plating solution does not contain fluoride, excluding rare earth elements, and the workpiece without low zone corrosion.

Hard chromium has a very wide application, such as mechanical molds, cylinder piston, measuring, cutting and drawing tools. Its other usage is for repairing of worn parts and workpiece with excessive cutting, so that these parts can be reused.

B, Simple technical processes:

Inspection—degreasing—water washing rinse—antipole—chrome plating—water washing—testing.

C, Technological parameters:

1, Chromic anhydride:(CrO3) 220 ~ 250g/L
2, Sulfate (SO42-): 2.2 ~ 2.5g/L
3, Trivalent chromium (Cr3+): 2 ~ 5g/L
4, Plating solution temperature: 50 ~ 55℃
5, Cathode current density: 30 ~ 60A/dm2

D, Operations and precautions

1, Workpieces size inspection before plating, machining surface conditions, according to the coating thickness to calculate the plating time accurately.
2, Good controling of the electroplating solution working conditions, observation frequently, pay attention to temperature changes, level changes, careful operation, fill out the operating record. According to the result to add medicine, then correct plating solution.
3, Check the quality of the coating layer after plating, size, clean, wire teeth, inside bore and other parts rust protection. Steel workpiece strike operating grade of steel, deburring edges.
4, If the acid spilled on the skin, should immediately rinse and clean with water.

Hard chrome machine plating process procedures

Hard chrome machine plating process procedures

5 necessary auxiliary machines for electroplating industry

5 necessary auxiliary machines for electroplating industry:

Filter and recycle filter equipment:

In order to ensure electroplating quality, the plating solution is required to filter regularly. While filter is the most commonly used filtration device in the chemical industry, and some kinds of electroplating also required ceaselessly cycling filtration on running. We can select the right filter based on plating situation and electroplating bath size as well as technological requirements.

Plating machine Filter

Plating machine Filter

Cathode moving or agitation device:

Some or most of plating, the cathode shall in condition of moving states, then the operating current can be increased, while bath solution give deserved function (usually brightness and dispersion capacity), and can prevent from cusp, corner gross plated, charred. But some types of plating can use equipment or agitation device to replace cathode moving. Mechanical agitation is a mixer which made of corrosion-resistant material, usually, it is driven by motor, but its speed is can not too high. While air stirring adopts the deoiled compressed air after filtering.

air

Heating or cooling machines:

Because of plating solution working at a certain temperature, so electroplating bath shall be equipped with heating devices. For example, temperature of brightness nickel plating should be maintained at 50 ℃, while chrome plating temperature is 50 ~ 60 ℃, but brightness acidity copper electroplating or brightness silver plating required temperature within 30 ℃. Thus, these requirements shall be met by means of heat exchange machinery. For heating, normally use direct heating method.

Plating bath:

Plating bath must be equipped with accessories including anode and anode or anode baskets or anode hook, electrode rods , power cables, etc..
Most anode basket used titanium as material, a few species electroplating adopt stainless steel or steel.
Electrode rod is conductive rod which used for hanging anode and cathode and also connected to power source. Usually made of copper or brass rod, slightly longer than the plating bath, the diameter size according to the current demand, but the diameter at least more than 5cm.
The key function of power cable is to ensure can go through needed current. The best material is copper plate, also multi-strand cable can be adopted, but cross sectional area requirements must be complied with.

plating bath

Plating bath

Plating hanger:

Hanger is the most important auxiliary tools for electroplating process. It is tool not only to make sure plating workpiece connected with cathode, but also has a direct impact on coating layer distribution and efficiency. Now there are professional hanger suppliers to offer general design hanger and also can customize according to users’ special requirements.

plating hanger

Plating hanger