PCB plating process knowledge data

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PCB plating process knowledge data

First. Electroplating process classification:

Acid Bright Copper Plating Nickel / Gold Plating Tin

Second. Process:

Pickling → full plate copper plating → graphic transfer → acid degreasing → secondary countercurrent rinsing → micro-etching → secondary → pickling → tin → secondary countercurrent rinsing

Countercurrent rinsing → pickling → graphic copper electroplating → secondary countercurrent rinsing → nickel plating → secondary washing → citric acid leaching → gold plating → recycling → 2-3 grade pure water washing → drying

three. Flow Description:

(A) pickling acid

① role and purpose:

Removal of surface oxides, activated surface, the general concentration of 5%, and some remained at about 10%, mainly to prevent the introduction of water caused by bath sulfuric acid content is not stable;

② acid leaching time should not be too long, to prevent oxidation of the board; in use for a period of time, the acid appears cloudy or copper content is too high should be promptly replaced, to prevent the pollution of copper plating and plate surface;

③ here should be used C.P grade sulfuric acid;

(B) the whole board Plating copper: also known as a copper, plate, Panel-plating ① role and purpose:

Protect the just deposited thin chemical copper, to prevent chemical oxidation of copper oxide erosion, by electroplating it to a certain extent

② full-board copper plating process parameters: the main components of copper sulfate bath and sulfuric acid, the use of high-acid low-copper formula to ensure uniformity of plating plate thickness distribution and deep hole deep plating capacity; sulfuric acid content and more In the 180 g / L, more than 240 g / L; copper sulfate content is generally about 75 g / L, the other bath was added a trace amount of chloride ions, as an auxiliary gloss and copper agent together play a gloss effect; copper The amount of light agent or the amount of open cylinder is generally 3-5ml / L, the addition of copper agent generally in accordance with the method of thousands of hours to supplement or according to the actual production board effect; the whole board plating current calculation generally 2A / square Multiply the board can be plated on the area, for the whole board is concerned, that plate length dm × width dm × 2 × 2A / DM2; copper cylinder temperature maintained at room temperature, the general temperature does not exceed 32 degrees, and more control At 22 degrees, so in the summer due to the temperature is too high, the copper cylinder is recommended to install cooling temperature control system;

③ process maintenance:

Daily according to 1000 hours to replenish the copper agent, add 100-150ml / KAH added; check the filter pump is working properly, with or without leakage; every 2-3 hours with a clean wet cloth to the cathode conductive rod Scrub clean; regular weekly analysis of copper copper sulfate (1 / week), sulfuric acid (1 / week), chloride (2 times / week) content, and through the Holzer test to adjust the light content, and Timely replenishment of related raw materials; Weekly to clean the anode conductive rod, the tank at both ends of the electrical connector, and promptly replenish the anode basket copper ball, with a low current 0.2-0.5ASD electrolysis 6-8 hours; monthly inspection anode titanium Basket is damaged, damaged should be promptly replaced; and check the bottom of the anode titanium basket is deposited with anode mud, if any, should be promptly cleaned; and continuous filtration with a carbon core 6-8 hours, while low current electrolysis impurity; every six months About the specific decision according to tank status whether the need for large treatment (activated carbon powder); every two weeks to replace the filter pump filter;

④ large processing procedures: A. Remove the anode, the anode poured out, wash the anode surface anode film, and then placed in a barrel copper anode, with a micro-etchant roughening copper surface to a uniform pink, washed with water After loading into the titanium basket, side into the acid tank spare B. The anode titanium basket and anode bag into 10% alkali soak 6-8 hours, washed with water, then dilute with 5% sulfuric acid, washed with water C, the transfer of the bath to the spare tank, adding 1-3ml / L of 30% hydrogen peroxide, began to heat until the temperature is increased to about 65 degrees open the air stirring, heat air stirring for 2-4 hours; D Turn off the air mixing, 3-5 grams / liter slowly dissolve the activated carbon into the bath solution, to be completely dissolved, open the air stirring, so heat 2-4 hours; E. Turn off the air mixing, heating, So that the active carbon slowly precipitated to the bottom of the tank; F until the temperature dropped to about 40 degrees, with 10um PP filter plus help filter filter tank to clean the work tank, open the air mixing, into the anode, hanging Into the electrolysis board, according to 0.2-0.5ASD current density low current electrolysis 6-8 hours, G. by laboratory analysis, adjust the tank Acid, copper sulfate, chloride ion content within the normal operating range; according to Hall channel test results to add light agent ;. H to be electrolysis board surface color uniformity, you can stop electrolysis, and then by 1-1.5ASD current density Electrolytic membrane treatment 1-2 hours until the anode to generate a layer of uniform and dense adhesion of black phosphorus can be good;

⑤ anode copper ball contains 0.3-0.6% of the phosphorus, the main purpose is to reduce the anode dissolution efficiency and reduce the production of copper powder;

⑥ Supplementary drugs, such as larger amount of added, such as copper sulfate, sulfuric acid; should be added after the low-current electrolysis; additional sulfuric acid should pay attention to safety, additional amount larger (10 liters above) should be divided into several times slowly fill Plus; otherwise it will cause the bath temperature is too high, light decomposition speed up, pollution bath;

⑦ additional chloride ion should pay special attention to, because the chloride ion content is particularly low (30-90ppm), additional time must be measured with a measuring cylinder or measuring cup before adding; 1ml hydrochloric acid chloride ions about 385ppm,

⑧ add drugs formula:

Copper sulfate (unit: kg) = (75-X) × tank volume (liter) / 1000

Sulfuric acid (unit: liter) = (10% -X) g / L × tank volume (liter)

Or (unit: liter) = (180-X) g / L × tank volume (liter) / 1840

Hydrochloric acid (unit: ml) = (60-X) ppm × tank volume (liter) / 385

(C) Acid degreasing

① purpose and purpose: remove the copper lines on the surface of the oxide, residual ink residue film to ensure that a copper and copper plating or electroplating between the binding force of nickel

② Remember where to use acid degreasing agent, why not alkaline degreasing agent and alkaline degreasing agent degreasing effect is better than acid degreasing agent? Mainly because the graphics ink is not alkali-resistant, will damage the graphics lines, so only the use of acid degreasing agent before the pattern plating.

③ only need to control the degreasing agent concentration and time of production, degreasing agent concentration of about 10%, time to ensure that in 6 minutes, the longer the time will not have an adverse effect; bath replacement is also in accordance with 15 square meters / liter work Liquid, add in accordance with 100 square meters 0.5-0.8L;

(D) micro-corrosion:

① Purpose and Function: Clean the roughened copper surface to ensure the bond between the patterned copper plating and the primary copper

② micro-etchant more sodium persulfate, the roughening rate of stable, washed well, sodium persulfate concentration generally controlled at about 60 grams / liter, the time control in about 20 seconds, the drug added by 100 square meters 3-4 kg ; Copper content controlled at 20 g / L or less;

(E) pickling

① role and purpose:

Removal of surface oxides, activated surface, the general concentration of 5%, and some remained at about 10%, mainly to prevent the introduction of water caused by bath sulfuric acid content is not stable;

② acid leaching time should not be too long, to prevent oxidation of the board; in use for a period of time, the acid appears cloudy or copper content is too high should be promptly replaced, to prevent the pollution of copper plating and plate surface;

③ here should be used C.P grade sulfuric acid;

(F) Graphical copper plating: also known as secondary copper, copper circuit

① Purpose and Function: In order to meet the rated current load of each line, each line and hole copper copper need to reach a certain thickness. The purpose of circuit copper plating is to thick hole copper and line copper to a certain thickness in time;

② other projects are the same plate plating

(VII) Electroplating Tin ① Purpose and Function: The purpose of electroplating pure tin is to use pure tin as a pure metal resist to protect the circuit from etching.

The bath is mainly composed of stannous sulfate, sulfuric acid and additives; the stannous sulfate content is controlled at about 35 g / l and the sulfuric acid is controlled at about 10%; the addition of the tinning additive is generally added according to the method of 1000 hrs or according to the actual The effect of the production of plate; tin plating current calculation by 1.5 amps / square decimeter multiplied by the board plating area; tin cylinder temperature maintained at room temperature, the general temperature of not more than 30 degrees, and more control at 22 degrees, so in Due to the temperature is too high in summer, tin cylinder cooling system is recommended to install cooling;

③ process maintenance:

Daily according to thousands of hours in a timely manner to add tin additives; check the filter pump is working properly, with or without leakage; every 2-3 hours a clean wet cloth to scrub the cathode conductive rod; regular weekly analysis Tin cylinder stannous sulfate (1 / week), sulfuric acid (1 / week), and through the Hall tank test to adjust the tinning additive content, and timely replenishment of related raw materials; weekly to clean the anode conductive rod, the tank two The end of the electrical connector; weekly low current 0.2-0.5ASD electrolysis 6-8 hours; monthly anode bags should be checked for damage, breakage should be promptly replaced; and check the bottom of the anode bag is stacked anode slime, if timely Cleaning every month with a continuous carbon-carbon filter 6-8 hours, while low-current electrolysis impurity; every six months or so depending on the tank liquid pollution status decide whether the need for large processing (activated carbon powder); every two weeks to replace the filter pump filter ;

⑨ large processing procedures: A. Remove the anode, remove the anode bag, with a copper brush cleaning the anode surface, washed washed, into the anode bag, into the acid tank spare B. The anode bag into 10% lye Soak for 6-8 hours, washed with water, and then soaked with 5% dilute sulfuric acid, washed with water after standby ;. C tank will be transferred to a spare tank, 3-5 grams / liter slowly dissolve activated carbon into the tank Liquid, to be completely dissolved, adsorption 4-6 hours, with 10um PP filter plus help filter powder filter tank to clean the work tank, into the anode, hanging into the electrolysis board, according to 0.2-0.5ASD current density Low current electrolysis 6-8 hours, D. by laboratory analysis, adjust the tank sulfuric acid, stannous sulfate content to the normal operating range; according to the Hall tank test results to add tin additives; E to be electrolysis board surface uniform color After that, stop electrolysis; F.

④ When supplements, such as adding a larger amount, such as stannous sulfate, sulfuric acid; Add should be low-current electrolysis; Supplementary sulfuric acid should pay attention to safety, additional amount larger (10 liters above) should be divided into several slow Additional; otherwise it will cause the bath temperature is too high, stannous oxide, to accelerate the tank aging;

⑤ drug add calculation formula:

Stannous sulfate (unit: kg) = (40-X) × tank volume (liter) / 1000

Sulfuric acid (unit: liter) = (10% -X) g / L × tank volume (liter)

Or (unit: liter) = (180-X) g / L × tank volume (liter) / 1840

(IX) Nickel plating

① purpose and purpose: nickel-plated layer as the main copper layer and the barrier between the gold layer to prevent mutual diffusion of gold and copper, affecting board solderability and life; at the same time the nickel layer also greatly increased the base of the gold layer Mechanical strength;

② full board copper plating process parameters: Add nickel plating additive generally according to the method of 1000 hours to supplement or according to the actual production board effect, add about 200ml / KAH; graph nickel plating current calculation generally by 2 A / Multiplied by the board can be plating area; nickel cylinder temperature is maintained at 40-55 degrees, the general temperature of about 50 degrees, so nickel cylinder to be installed heating, temperature control system;

③ process maintenance:

Daily according to thousands of hours to replenish nickel plating additives; check whether the filter pump is working properly, with or without leakage; every 2-3 hours to apply a clean wet cloth to scrub the cathode conductive rod; regular weekly analysis of copper Cylinder nickel sulfate (nickel sulfamate) (1 time / week), nickel chloride (1 time / week), boric acid (1 time / week) content, and through the Hall groove test to adjust the nickel plating additive content, and timely Add relevant raw materials; Weekly to clean the anode conductive rod, both ends of the tank electrical connector, promptly added titanium anode basket nickel angle, with a low current 0.2-0.5ASD electrolysis 6-8 hours; monthly check the anode titanium basket Bags are damaged, damaged should be promptly replaced; and check the bottom of the anode titanium basket is deposited with anode mud, if any, should be promptly cleaned; and continuous filtration with a carbon core 6-8 hours, while low current electrolysis impurity; every six months or so Specific decisions based on the tank liquid state whether the need for large processing (activated carbon powder); every two weeks to replace the filter cartridge filter;

④ large processing procedures: A. Remove the anode, the anode poured out, wash the anode, and then placed in the barrel of nickel packing, with micro-etchant surface roughened nickel angle to uniform pink, washed with water after the installation Into the titanium basket, side into the acid tank spare B. The anode titanium basket and anode bag into 10% alkali soak 6-8 hours, washed with water, then 5% dilute sulfuric acid soaking, washed with water after standby; C. The bath was transferred to the spare tank, adding 1-3ml / L of 30% hydrogen peroxide, began to heat until the temperature was added to about 65 degrees open the air stirring, heat air stirring for 2-4 hours; D. turn off Air agitation, 3-5 grams / liter of activated carbon slowly dissolved into the bath solution to be dissolved thoroughly, open the air stirring, so heat 2-4 hours; E turn off the air stirring, warming, so that activated carbon F slowly until the temperature dropped to about 40 degrees, with 10um PP filter plus help filter powder filter tank to clean the work tank, open the air mixing, into the anode, hang the electrolysis board , According to 0.2-0.5ASD current density low current electrolysis 6-8 hours, G. By laboratory analysis, adjust the tank of nickel sulfate or ammonia Nickel sulfonate, nickel chloride, boric acid content to the normal operating range; according to the Hall groove test results added nickel additive ;. H to be electrolysis board surface color uniformity, you can stop electrolysis, and then by 1-1.5ASD Current density for electrolytic treatment 10-20 minutes to activate the anode;

⑤ supplementary drugs, such as adding a larger amount, such as nickel sulfate or nickel sulfamate, nickel chloride, after the addition should be low-current electrolysis; additional boric acid should be added to the amount of boric acid into a clean anode bag hanging Nickel cylinder can not directly join the tank;

⑥ recommended after nickel plating plus a recovery of washing, with pure water to open the cylinder, can be used to supplement the nickel cylinder due to heating and volatile levels, recycling after washing two secondary counter-current rinsing;

⑦ add drugs formula:

Nickel sulfate (unit: kg) = (280-X) × tank volume (liter) / 1000

Nickel chloride (unit: kg) = (45-X) × tank volume (liter) / 1000

Boric acid (unit: kg) = (45-X) × tank volume (liter) / 1000

(10) Electroplating Gold: It is divided into electroplating hard gold (gold alloy) and water gold (pure gold) technology. The composition of hard gold plating and soft gold plating bath is basically the same except that there is some trace nickel or cobalt Or iron and other elements;

① purpose and purpose: gold as a precious metal, with good solderability, oxidation resistance, corrosion resistance, low contact resistance, good wear resistance alloy, and other fine features;

② current circuit board gold plating mainly citrate bath gold bath, with its simple maintenance, simple operation and convenient access to a wide range of applications;

③ gold and gold water content control in 1 g / l or so, PH value of about 4.5, the temperature of 35 degrees, the proportion of 14 Baume degrees around the current density of about 1ASD;

④ mainly add drugs to adjust the PH value of acid-adjusted salt and alkali-adjusted salt, adjust the proportion of conductive salt and gold-plated additive and gold salts, etc.;

⑤ In order to protect the gold cylinder, a citric acid dip tank should be added before the cylinder, which can effectively reduce the pollution to the cylinder and keep the cylinder stable.

⑥ gold plate plating after the application of a pure water for recycling washing, but also can be used to supplement the level of gold cylinder evaporation changes, recycling washed followed by two countercurrent pure water wash, gold plate after washing into 10 g / l of lye In case of gold plate oxidation;

⑦ gold cylinder should be made of platinum-plated titanium mesh anode, stainless steel 316 is generally easy to dissolve, resulting in nickel-iron chromium and other metal pollution of the cylinder, resulting in gilded white, exposed plating, black and other defects;

⑧ gold cylinder organic carbon continuous filtration, and add the appropriate amount of gold-plated additives.

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