PCB electroplating process knowledge information[Copy link]
I. Classification of electroplating process: Acid bright copper electroplating Nickel/gold electroplating Tin electroplating II. Process flow: Acid immersion → Full board copper electroplating → Pattern transfer → Acid degreasing → Secondary countercurrent rinsing → Microetching → Secondary → Acid immersion → Tin plating → Secondary countercurrent rinsing Countercurrent rinsing → Acid immersion → Pattern copper plating → Secondary countercurrent rinsing → Nickel plating → Secondary water washing → Citric acid immersion → Gold plating → Recycling → 2-3 level pure water washing → Drying III. Process description: (I) Acid immersion ① Function and purpose: Remove the oxide on the board surface and activate the board surface. The general concentration is 5%, and some are kept at around 10%. The main purpose is to prevent moisture from entering the bath and causing unstable sulfuric acid content; ② The acid immersion time should not be too long to prevent board surface oxidation; after a period of use, if the acid becomes turbid or the copper content is too high, it should be replaced in time to prevent contamination of the copper electroplating tank and the surface of the board; ③ CP grade sulfuric acid should be used here; (II) Full board copper plating: also called primary copper, board electricity, Panel-plating ① Function and purpose: ② Relevant process parameters of full-board copper plating: the main components of the bath are copper sulfate and sulfuric acid, and a high-acid and low-copper formula is used to ensure the uniformity of the thickness distribution of the board surface during electroplating and the deep plating ability of deep holes and small holes; the sulfuric acid content is mostly 180 g/L, and the maximum is 240 g/L; the copper sulfate content is generally around 75 g/L, and a small amount of chloride ions is added to the bath as an auxiliary gloss agent and copper light agent to jointly exert the gloss effect; the amount of copper light agent added or the amount of opening the cylinder is generally 3-5 ml/L, and the addition of copper light agent is generally supplemented according to the kiloampere-hour method or according to the actual production board effect; the current calculation for full-board electroplating is generally 2 amperes/square decimeter multiplied by the electroplatable area on the board. For the full-board current, the board length dm×board width dm×2×2A/ DM2; The temperature of the copper cylinder is maintained at room temperature, generally not exceeding 32 degrees, and is mostly controlled at 22 degrees. Therefore, in summer, due to the high temperature, it is recommended to install a cooling temperature control system on the copper cylinder; ③ Process maintenance: Replenish copper brightener in time according to kiloampere-hours every day, and add it at 100-150ml/KAH; check whether the filter pump is working properly and whether there is any leakage; use a clean wet rag to clean the cathode conductive rod every 2-3 hours; regularly analyze the copper sulfate (1 time/week), sulfuric acid (1 time/week), and chloride ion (2 times/week) content of the copper cylinder every week, and adjust the brightener content through the Hall cell test, and replenish relevant raw materials in time; clean the anode conductive rod and the electrical connectors at both ends of the tank every week, replenish the anode copper balls in the titanium basket in time, and use low current 0.2-0.5ASD electrolysis for 6-8 hours; check whether the titanium basket bag of the anode is damaged every month, and replace it in time if it is damaged; check whether there is anode mud accumulated at the bottom of the anode titanium basket, if so, clean it in time; and use carbon core to filter continuously for 6-8 hours, and remove impurities by low current electrolysis; decide whether large-scale treatment (activated carbon powder) is needed every six months or so according to the pollution status of the tank liquid; replace the filter element of the filter pump every two weeks;] ④ Major treatment procedures: A. Take out the anode, pour out the anode, clean the anode film on the surface of the anode, and then put it in the barrel of copper anode packaging, use micro-etching agent to roughen the surface of the copper corner until it is uniformly pink, rinse with water and dry, put it in the titanium basket, and then put it in the acid tank for standby B. Soak the anode titanium basket and anode bag in 10% alkali solution for 6-8 hours, rinse with water and dry, then soak in 5% dilute sulfuric acid, rinse with water and dry for standby; C. Transfer the tank liquid to the standby tank, add 1-3ml/L of 30% hydrogen peroxide, start heating, turn on the air stirring when the temperature reaches about 65 degrees, and keep the air stirring for 2-4 hours; D. Turn off the air stirring, slowly dissolve the activated carbon powder into the tank liquid at 3-5g/L, and turn on the air stirring after it is completely dissolved, and keep it warm for 2-4 hours; E. Turn off the air stirring, heat up, and let the activated carbon powder slowly settle to the bottom of the tank; F. When the temperature drops to about 40 degrees, use a 10um PP filter element and filter powder to filter the tank liquid into a clean working tank, turn on the air stirring, put in the anode, hang the electrolytic plate, and electrolyze at a low current density of 0.2-0.5ASD for 6-8 hours. G. After laboratory analysis, adjust the sulfuric acid, copper sulfate, and chloride ion content in the tank to the normal operating range; add light agent according to the Hall cell test results; H. When the color of the electrolytic plate surface is uniform, stop the electrolysis, and then perform electrolytic film treatment at a current density of 1-1.5ASD for 1-2 hours until a uniform, dense, and well-adhesive black phosphorus film is formed on the anode; I. Test plating is OK. ⑤ The anode copper ball contains 0.3-0.6% phosphorus, the main purpose is to reduce the efficiency of anode dissolution and reduce the generation of copper powder; ⑥ When adding chemicals, if the amount added is large, such as copper sulfate and sulfuric acid; low current electrolysis should be performed after adding; pay attention to safety when adding sulfuric acid. When the amount added is large (more than 10 liters), it should be added slowly in several times; otherwise, the bath temperature will be too high, the decomposition of the light agent will be accelerated, and the bath will be polluted; ⑦ Pay special attention to the addition of chloride ions, because the chloride ion content is particularly low (30-90ppm),When adding, be sure to use a measuring cylinder or measuring cup to weigh accurately before adding; 1ml hydrochloric acid contains about 385ppm of chloride ions. ⑧ Calculation formula for adding drugs: 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 (III) Acidic degreasing ① Purpose and function: Remove oxides, ink residues and glue on the copper surface of the circuit to ensure the bonding strength between the copper and the electroplated copper or nickel of the pattern ② Remember that an acid degreaser is used here. Why not an alkaline degreaser and why the alkaline degreaser has a better degreasing effect than the acid degreaser? This is mainly because the graphic ink is not alkali-resistant and will damage the graphic circuit. Therefore, only an acid degreaser can be used before graphic electroplating. ③ During production, it is only necessary to control the degreasing agent concentration and time. The degreasing agent concentration is about 10%, and the time is guaranteed to be 6 minutes. A slightly longer time will not have adverse effects. The tank liquid is also replaced according to 15 square meters/liter of working liquid, and the additional addition is 0.5-0.8L per 100 square meters; (IV) Micro-etching: ① Purpose and function: Clean and roughen the copper surface of the circuit to ensure the bonding strength between the graphic electroplated copper and the primary copper. ② Micro-etching agents mostly use sodium persulfate, which has a stable and uniform roughening rate and good water washing properties. The sodium persulfate concentration is generally controlled at about 60 grams/liter, the time is controlled at about 20 seconds, and the chemical addition is 3-4 kilograms per 100 square meters; the copper content is controlled below 20 grams/liter; other maintenance and cylinder replacement are the same as copper micro-etching. (V) Acid Dipping ① Function and Purpose: Remove the oxide on the board surface and activate the board surface. The general concentration is 5%, and some are kept at around 10%, mainly to prevent moisture from entering and causing unstable sulfuric acid content in the bath; ② The acid dipping time should not be too long to prevent oxidation of the board surface; after a period of use, if the acid solution becomes turbid or the copper content is too high, it should be replaced in time to prevent contamination of the electroplating copper cylinder and the surface of the board; ③ CP grade sulfuric acid should be used here; (VI) Graphic copper plating: also called secondary copper, circuit copper plating ① Purpose and Function: In order to meet the rated current load of each circuit, each circuit and hole copper needs to reach a certain thickness after copper plating. The purpose of circuit copper plating is to thicken the hole copper and circuit copper to a certain thickness in time; ② Other items are the same as full board electroplating. (VII) Electroplating tin. ① Purpose and function: The purpose of graphic electroplating of pure tin is to use pure tin as a metal anti-corrosion layer to protect circuit etching. ② The bath liquid is mainly composed of stannous sulfate, sulfuric acid and additives. The content of stannous sulfate is controlled at about 35 g/L, and the content of sulfuric acid is controlled at about 10%. The addition of tin plating additives is generally supplemented according to the kiloampere-hour method or according to the actual production board effect. The current calculation of electroplating tin is generally 1.5 amperes/square decimeter multiplied by the electroplatable area on the board. The temperature of the tin tank is maintained at room temperature, generally not exceeding 30 degrees, and is mostly controlled at 22 degrees. Therefore, in summer, due to the high temperature, it is recommended to install a cooling temperature control system on the tin tank. ③ Process maintenance: Replenish tin plating additives in time according to kiloampere-hours every day; check whether the filter pump is working properly and whether there is any leakage; use a clean wet rag to clean the cathode conductive rod every 2-3 hours; regularly analyze the tin tank stannous sulfate (once a week) and sulfuric acid (once a week) every week, and adjust the content of tin plating additives through Hall cell test, and replenish relevant raw materials in time; clean the anode conductive rod and the electrical connectors at both ends of the tank every week; use low current 0.2-0.5ASD for electrolysis for 6-8 hours every week; check whether the anode bag is damaged every month, and replace it in time if it is damaged; and check whether there is anode mud accumulated at the bottom of the anode bag, if so, clean it in time; use carbon core to filter continuously for 6-8 hours every month, and remove impurities by low current electrolysis at the same time; decide whether large-scale treatment (activated carbon powder) is needed every six months or so according to the pollution status of the tank liquid; replace the filter element of the filter pump every two weeks; Major treatment procedures: A. Take out the anode, remove the anode bag, clean the anode surface with a copper brush, rinse with water and dry, put it into the anode bag, and put it into the acid tank for standby. B. Soak the anode bag in 10% alkali solution for 6-8 hours, rinse with water and dry, then soak it in 5% dilute sulfuric acid, rinse with water and dry for standby. C. Transfer the tank liquid to the standby tank, slowly dissolve the activated carbon powder into the tank liquid at 3-5 grams/liter, after it is completely dissolved, adsorb for 4-6 hours, use a 10um PP filter element and filter powder to filter the tank liquid into a clean working tank, put in the anode, hang the electrolytic plate, and electrolyze at a low current density of 0.2-0.5ASD for 6-8 hours. D. After laboratory analysis, adjust the sulfuric acid and stannous sulfate content in the tank to the normal operating range; supplement tin plating additives according to the results of the Hall tank test; E. Stop electrolysis when the color of the electrolytic plate surface is uniform; F. Test plating OK.That's it; ④ When supplementing drugs, if the added amount is large, such as stannous sulfate, sulfuric acid; after adding, low current electrolysis should be performed; pay attention to safety when adding sulfuric acid. When the added amount is large (more than 10 liters), it should be added slowly in several times; otherwise, the bath temperature will be too high, stannous sulfate will oxidize, and the aging of the bath will be accelerated; ⑤ Drug addition calculation formula: Stannous sulfate (unit: kg) = (40-X) × bath volume (liter) / 1000 Sulfuric acid (unit: liter) = (10%-X) g/L × bath volume (liter) or (unit: liter) = (180-X) g/L × bath volume (liter) / 1840 (IX) Nickel plating ① Purpose and function: The nickel plating layer is mainly used as a barrier layer between the copper layer and the gold layer to prevent the mutual diffusion of gold and copper, which affects the solderability and service life of the board; at the same time, the nickel layer also greatly increases the mechanical strength of the gold layer; ② Full-board copper electroplating related process parameters: The addition of nickel plating additives is generally supplemented according to the kiloampere-hour method or according to the actual production board effect, and the addition amount is about 200ml/KAH; the current calculation of graphic nickel plating is generally 2 amperes/square decimeter multiplied by the electroplatable area on the board; the nickel cylinder temperature is maintained at 40-55 degrees, and the general temperature is around 50 degrees, so the nickel cylinder must be equipped with a heating and temperature control system; ③ Process maintenance: Replenish nickel plating additives in time according to kiloampere-hours every day; check whether the filter pump is working properly and whether there is any leakage; use a clean wet rag to clean the cathode conductive rod every 2-3 hours; regularly analyze the content of nickel sulfate (nickel sulfamate) (1 time/week), nickel chloride (1 time/week), and boric acid (1 time/week) in the copper cylinder every week, and adjust the content of nickel plating additives through Hall cell test, and replenish relevant raw materials in time; clean the anode conductive rod and the electrical connectors at both ends of the tank body every week, replenish the anode nickel corners in the titanium basket in time, and use low current 0.2-0.5ASD electrolysis for 6-8 hours; check whether the titanium basket bag of the anode is damaged every month, and replace it in time if it is damaged; check whether there is anode mud accumulated at the bottom of the anode titanium basket, if so, clean it in time; and use carbon core to filter continuously for 6-8 hours, and remove impurities at the same time by low current electrolysis; decide whether a large treatment (activated carbon powder) is needed every six months or so according to the pollution status of the tank liquid; replace the filter element of the filter pump every two weeks; ④Major treatment procedure: A. Take out the anode, pour out the anode, clean the anode, and then put it in the barrel of nickel corner packaging. Use micro-etching agent to roughen the surface of the nickel corner until it is uniformly pink. After washing and drying, put it into the titanium basket and then into the acid tank for standby. B. Soak the anode titanium basket and anode bag in 10% alkali solution for 6-8 hours, wash and dry, and then soak them in 5% dilute sulfuric acid, wash and dry and set aside; C. Transfer the tank liquid to the spare tank, add 1-3ml/L of 30% hydrogen peroxide, start heating, turn on the air stirring when the temperature reaches about 65 degrees, and keep the air stirring for 2-4 hours; D. Turn off the air stirring, slowly dissolve the activated carbon powder into the tank liquid at 3-5g/L, and turn on the air stirring after it is completely dissolved, and keep it warm for 2-4 hours ;E. Turn off the air stirring, heat up, and let the activated carbon powder slowly settle to the bottom of the tank;F. When the temperature drops to about 40 degrees, use a 10um PP filter element and filter powder to filter the tank liquid into a clean working tank, turn on the air stirring, put in the anode, hang the electrolytic plate, and electrolyze at a low current density of 0.2-0.5ASD for 6-8 hours.G. After laboratory analysis, adjust the nickel sulfate or nickel sulfamate, nickel chloride, and boric acid content in the tank to the normal operating range; supplement nickel plating additives according to the Hall cell test results;H. When the color of the electrolytic plate surface is uniform, stop the electrolysis, and then perform electrolysis at a current density of 1-1.5ASD for 10-20 minutes to activate the anode;I. Test plating OK. ⑤ When adding chemicals, if the amount added is large, such as nickel sulfate or nickel sulfamate, nickel chloride, low current electrolysis should be performed after adding; when adding boric acid, the supplementary amount of boric acid should be put into a clean anode bag and hung in the nickel cylinder, and it cannot be added directly into the tank; ⑥ After nickel plating, it is recommended to add a recovery water wash, open the tank with pure water, which can be used to replenish the liquid level of the nickel cylinder that evaporates due to heating, and then connect the recovery water wash to the secondary countercurrent rinse; ⑦ Chemical addition calculation 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 (Ten) Electroplating gold: It is divided into electroplating hard gold (gold alloy) and water gold (pure gold) processes. The composition of the hard gold plating and soft gold bath liquid is basically the same, except that there are some trace metal elements such as nickel, cobalt or iron in the hard gold bath; ① Purpose and function: As a precious metal, gold has good solderability, oxidation resistance, corrosion resistance, low contact resistance, good alloy wear resistance and other excellent characteristics; ② At present, the main electroplating gold for circuit boards is citric acid gold bath, which is widely used for its simple maintenance and simple and convenient operation; ③ The gold content of water gold is controlled at about 1 gram/liter, the pH value is about 4.5, the temperature is 35 degrees, the specific gravity is about 14 degrees Baume, and the current density is about 1ASD; ④ The main additives include acid salt and alkaline salt for adjusting pH value, conductive salt for adjusting specific gravity, gold plating additives and gold salt, etc.; ⑤ In order to protect the gold cylinder, a citric acid immersion tank should be added in front of the gold cylinder, which can effectively reduce the pollution to the gold cylinder and keep the gold cylinder stable; ⑥ After the gold plate is electroplated, a pure water wash should be used as a recovery water wash, and it can also be used to replenish the liquid level of the evaporation change of the gold cylinder. After the recovery water wash, a secondary countercurrent pure water wash is connected. After the gold plate is washed, 10 grams/liter of alkali solution is added to prevent the gold plate from oxidizing; ⑦ The gold cylinder should use platinum-plated titanium mesh as the anode. Generally, stainless steel 316 is easy to dissolve, resulting in nickel, iron, chromium and other metals polluting the gold cylinder, causing defects such as whitening, exposed plating, and blackening of the gold plating; ⑧ Organic pollution in the gold cylinder should be filtered continuously with a carbon core and supplemented with an appropriate amount of gold plating additives.After laboratory analysis, adjust the nickel sulfate or nickel sulfamate, nickel chloride, and boric acid content in the tank to within the normal operating range; supplement nickel plating additives according to the results of the Hall cell test; H. After the color of the electrolytic plate surface is uniform, stop electrolysis, and then perform electrolysis at a current density of 1-1.5ASD for 10-20 minutes to activate the anode; I. Test plating is OK. ⑤ When supplementing chemicals, if the added amount is large, such as nickel sulfate or nickel sulfamate, nickel chloride, low current electrolysis should be performed after addition; when adding boric acid, the supplementary amount of boric acid should be put into a clean anode bag and hung in the nickel cylinder, and it cannot be added directly to the tank; ⑥ After nickel plating, it is recommended to add a recovery water wash, open the cylinder with pure water, which can be used to replenish the liquid level of the nickel cylinder due to heating, and connect the recovery water wash with a secondary countercurrent rinse; ⑦ Chemical addition calculation 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 (X) Gold plating: It is divided into hard gold plating (gold alloy) and water gold (pure gold) processes. The composition of the hard gold plating and soft gold bath liquid is basically the same, except that there are some trace metal elements such as nickel, cobalt or iron in the hard gold bath; ① Purpose and function: Gold, as a precious metal, has good solderability, oxidation resistance, corrosion resistance, low contact resistance, good alloy wear resistance and other excellent characteristics; ② At present, the main gold plating method for circuit boards is citric acid gold bath, which is widely used for its simple maintenance and convenient operation; ③ The gold content in water is controlled at about 1 gram/liter, the pH value is about 4.5, the temperature is 35 degrees, the specific gravity is about 14 degrees Baume, and the current density is about 1ASD; ④ The main added chemicals are acid adjustment salt and alkaline adjustment salt for adjusting the pH value, conductive salt for adjusting the specific gravity, gold plating supplementary additives and gold salts, etc.; ⑤ In order to protect the gold cylinder, a citric acid immersion tank should be added in front of the gold cylinder, which can effectively reduce the pollution to the gold cylinder and keep the gold cylinder stable; ⑥ After the gold plate is electroplated, it should be washed with pure water as a recycling water. It can also be used to replenish the liquid level of the gold cylinder due to evaporation. After the recycling water washing, it should be washed with secondary countercurrent pure water. After the gold plate is washed, 10 grams/liter of alkali solution should be added to prevent the gold plate from oxidizing; ⑦ The gold cylinder should use platinum-plated titanium mesh as the anode. Generally, stainless steel 316 is easy to dissolve, causing metals such as nickel, iron, and chromium to contaminate the gold cylinder, resulting in defects such as whitening, exposed plating, and blackening of the gold plated; ⑧ The organic pollution of the gold cylinder should be continuously filtered with a carbon core, and an appropriate amount of gold plating additives should be added. After laboratory analysis, adjust the nickel sulfate or nickel sulfamate, nickel chloride, and boric acid content in the tank to within the normal operating range; supplement nickel plating additives according to the results of the Hall cell test; H. After the color of the electrolytic plate surface is uniform, stop electrolysis, and then perform electrolysis at a current density of 1-1.5ASD for 10-20 minutes to activate the anode; I. Test plating is OK. ⑤ When supplementing chemicals, if the added amount is large, such as nickel sulfate or nickel sulfamate, nickel chloride, low current electrolysis should be performed after addition; when adding boric acid, the supplementary amount of boric acid should be put into a clean anode bag and hung in the nickel cylinder, and it cannot be added directly to the tank; ⑥ After nickel plating, it is recommended to add a recovery water wash, open the cylinder with pure water, which can be used to replenish the liquid level of the nickel cylinder due to heating, and connect the recovery water wash with a secondary countercurrent rinse; ⑦ Chemical addition calculation 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 (X) Gold plating: It is divided into hard gold plating (gold alloy) and water gold (pure gold) processes. The composition of the hard gold plating and soft gold bath liquid is basically the same, except that there are some trace metal elements such as nickel, cobalt or iron in the hard gold bath; ① Purpose and function: Gold, as a precious metal, has good solderability, oxidation resistance, corrosion resistance, low contact resistance, good alloy wear resistance and other excellent characteristics; ② At present, the main gold plating method for circuit boards is citric acid gold bath, which is widely used for its simple maintenance and convenient operation; ③ The gold content in water is controlled at about 1 gram/liter, the pH value is about 4.5, the temperature is 35 degrees, the specific gravity is about 14 degrees Baume, and the current density is about 1ASD; ④ The main added chemicals are acid adjustment salt and alkaline adjustment salt for adjusting the pH value, conductive salt for adjusting the specific gravity, gold plating supplementary additives and gold salts, etc.; ⑤ In order to protect the gold cylinder, a citric acid immersion tank should be added in front of the gold cylinder, which can effectively reduce the pollution to the gold cylinder and keep the gold cylinder stable; ⑥ After the gold plate is electroplated, it should be washed with pure water as a recycling water. It can also be used to replenish the liquid level of the gold cylinder due to evaporation. After the recycling water washing, it should be washed with secondary countercurrent pure water. After the gold plate is washed, 10 grams/liter of alkali solution should be added to prevent the gold plate from oxidizing; ⑦ The gold cylinder should use platinum-plated titanium mesh as the anode. Generally, stainless steel 316 is easy to dissolve, causing metals such as nickel, iron, and chromium to contaminate the gold cylinder, resulting in defects such as whitening, exposed plating, and blackening of the gold plated; ⑧ The organic pollution of the gold cylinder should be continuously filtered with a carbon core, and an appropriate amount of gold plating additives should be added.
提升卡
变色卡
千斤顶
京公网安备 11010802033920号
