CN112469209B - Method for synchronously metalizing metal layer and nonmetal layer in hole of PCB (printed circuit board) - Google Patents
Method for synchronously metalizing metal layer and nonmetal layer in hole of PCB (printed circuit board) Download PDFInfo
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Abstract
The invention provides a method for synchronously metalizing a metal layer and a non-metal layer in a hole of a PCB (printed circuit board), which sequentially comprises the following steps: degreasing, etching, silanization, baking and curing, activation and nickel plating; the silane liquid used for the silanization treatment comprises a silane coupling agent, a stabilizing agent and an accelerating agent in a mass ratio of 1-5: 0.1-10: 0.1-1. The invention can realize the synchronous metallization of the metal layer and the nonmetal layer in the hole, solve the problem of plating leakage in the hole and obtain the nickel plating layer with compact and uniform structure. The method does not need to carry out the procedures of colloid palladium activation and colloid debonding, simplifies the production process, has small corrosion to the aluminum substrate, and the hole metallization coating obtained by the method has the characteristics of good smoothness, good binding force and the like, and is suitable for industrial large-scale stable production.
Description
Technical Field
The invention relates to the field of printed circuit boards, in particular to a method for synchronously metalizing a metal layer and a nonmetal layer in a hole of a PCB (printed circuit board).
Background
PCB circuit boards, also known as printed circuit boards, are providers of electrical connections for electronic components. The printed circuit board is developed from a single-layer board to a double-sided board, a multi-layer board and a flexible board, and is continuously developed towards high precision, high density and high reliability, so that the size is continuously reduced, the cost is reduced, the performance is improved, and the printed circuit board still keeps strong vitality in the development process of future electronic products. Along with the development of light, thin, small, high-density and multifunctional electronic products, the assembly density and the integration of elements on a printed circuit board are higher and higher, the power consumption is higher and higher, the requirement on the heat dissipation performance of a PCB substrate is more and more urgent, and if the heat dissipation performance of the PCB substrate is not good, the components on the circuit board are overheated to influence the performance of the whole machine.
The aluminum substrate is a unique metal-based copper-clad plate, has good thermal conductivity, electrical insulation, high pressure resistance, bending resistance, machining resistance and the like, and is widely applied to the industries of avionics, automobiles, communication, medical treatment, sound equipment and the like. However, aluminum is one of the more active metal elements, the standard electrode has low potential, and is easily oxidized in the air to generate a loose oxide film, so that the corrosion resistance is poor, the hardness is low, and the wear resistance is poor. In the processing process of the PCB aluminum substrate, because the activity of metal aluminum is higher, if copper is directly deposited, the copper deposition solution is a strong alkaline solution and can react with the aluminum substrate, so that the copper deposition cannot be successful. In our research work, the technical solution of patent CN109898115A has successfully solved the above problems, and electroless nickel plating can be selected to metalize the aluminum alloy, and then copper deposition is performed.
However, since the structure of the PCB aluminum substrate is: epoxy resin-aluminum alloy-epoxy resin, so that an epoxy resin layer and an aluminum alloy layer, namely a non-metal layer and a metal layer, exist in the hole of the aluminum substrate at the same time. The conventional aluminum alloy metallization treatment adopts a zinc dipping method, and utilizes the replacement of a zinc layer and nickel ions in a chemical nickel plating solution to carry out chemical nickel plating to obtain a nickel plating layer. The invention patent CN109898115A discloses that an ionic palladium activating solution is used to activate a substrate, which can solve the problem of metallization of an aluminum alloy layer, but for a non-metal layer of epoxy resin, chemical nickel plating cannot be achieved because the ionic palladium activating solution cannot be adsorbed during activation, and therefore, synchronous metallization of a metal layer and a non-metal layer in a hole of a PCB aluminum substrate cannot be achieved, which may have a serious influence on the bonding force of a subsequent plating layer on the hole wall.
For a conventional PCB substrate, such as an FR-4 copper clad laminate, the hole metallization process is as follows: degreasing → hole wall adjustment → coarsening → presoaking → colloid palladium activation → dispergation → chemical copper deposition, but the process is not suitable for the hole metallization of the PCB aluminum substrate, and the main reasons are as follows: the activation of the colloidal palladium is carried out in an acid environment, when the PCB aluminum substrate is placed in an activating solution, palladium colloid can be adsorbed on the surface of the nonmetal layer (epoxy resin) in the hole, but the standard electrode potential of the metal layer (aluminum alloy) is low, and the reaction is easy to occur in the acid, so that the obtained palladium layer is loose, and the plating layer performance can be influenced in the subsequent metallization process; secondly, after the activation of the colloid palladium, the colloid palladium needs to be peptized, if the peptization is not complete, the palladium layer with catalytic activity cannot be exposed, so that the plating leakage phenomenon is caused, and the peptizing solution is generally acid or alkali, so that the aluminum layer can be corroded, and the bonding force of a subsequent metalized plating layer is influenced; finally, the process is complicated, and most of the steps are carried out in a strong acid or alkaline environment, so that excessive etching is carried out on the aluminum alloy layer, the aluminum layer is uneven, the problem of unevenness of a subsequent coating is caused, and the process is not favorable for large-scale production.
In summary, a method for realizing the hole metallization of the PCB aluminum substrate does not exist so far, and the hole metallization process of the conventional substrate has many defects and is complex and cannot meet the current enterprise requirements. Therefore, research and development of synchronous metallization technology of metal layers and nonmetal layers in holes of the PCB aluminum substrate, which is suitable for industrial large-scale production, simple process, environment-friendly and the like, become important research points in the field.
Disclosure of Invention
In order to overcome the defects and shortcomings of complex process, plating leakage, uneven plating layer, incapability of synchronously metalizing a metal layer and a nonmetal layer in a hole and the like in the prior art, the invention provides a method for synchronously metalizing the metal layer and the nonmetal layer in the hole of a PCB (printed circuit board).
A method for synchronously metalizing a metal layer and a nonmetal layer in a hole of a PCB aluminum substrate comprises the following steps:
s1: placing the aluminum substrate in alkaline degreasing fluid, performing degreasing treatment in the hole of the aluminum substrate, and removing an oxide film on the surface of a metal layer in the hole;
s2: placing the aluminum substrate processed in the step S1 into an alkaline etching solution for etching;
s3: placing the aluminum substrate processed in the step S2 into silane liquid for silanization;
s4: placing the aluminum substrate processed in the step S3 into an oven for baking and curing;
s5: putting the aluminum substrate processed in the step S4 into an activating solution for activation;
s6: putting the aluminum substrate processed in the step S5 into a nickel plating solution for metallization to obtain a nickel plated product;
the silane liquid comprises a silane coupling agent, a stabilizer and an accelerator in a mass ratio of 1-5: 0.1-10: 0.1-1.
In the invention, the treated aluminum substrate is washed clean by the deionized water in the steps, and then the next step is carried out, so that the solution pollution in the next step is avoided.
Optionally, the accelerator is one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium acetate, sodium carbonate and sodium bicarbonate.
Optionally, the stabilizer is alcohol and/or a surfactant, and the concentration of the stabilizer is 1-100 ml/L.
Optionally, the alcohol is one or more of methanol, ethanol and propanol; the surfactant is one or more of polyethylene glycol, octyl phenol polyoxyethylene ether and lauryl sodium sulfate.
Optionally, the temperature of the silane liquid is 0-70 ℃, and the silanization time is 10-120 s, so that the silanization effect is improved.
Optionally, the alkaline degreasing fluid comprises sodium phosphate, sodium carbonate and sodium hydroxide, the concentration of the sodium phosphate is 10-50 g/L, the concentration of the sodium carbonate is 10-50 g/L, the concentration of the sodium hydroxide is 5-10 g/L, and the alkaline degreasing fluid removes oil stains on the surface and in holes of the aluminum substrate, so that the coating binding force formed subsequently is improved.
Optionally, the alkali etching solution is one or two of sodium hydroxide and potassium hydroxide, the concentration of the alkali etching solution is 10-100 g/L, etching is favorable for improving the effect of subsequent nickel plating, and the quality of a plating layer is ensured.
Optionally, the activation solution comprises palladium chloride, hydrochloric acid and ammonium chloride, the concentration of the palladium chloride is 30-500 ppm, the concentration of the hydrochloric acid is 1-100 ml/L, and the concentration of the ammonium chloride is 10-1000 ppm, so that the activation is beneficial to improving the effect of subsequent nickel plating and the electroplating efficiency.
Optionally, the temperature of the alkaline degreasing liquid is 30-80 ℃, and the time of degreasing treatment is 3-6 min; the temperature of the alkali etching solution is 20-80 ℃, and the etching time is 10-100 s; the temperature of the activation solution is 20-50 ℃, and the activation time is 30-120 s; the temperature of the chemical nickel plating solution is 70-90 ℃, and the nickel plating time is 5-15 min; the baking curing temperature is 50-120 ℃, and the baking curing time is 1-5 min.
Optionally, the nickel plating solution comprises the following components: the mass ratio is (15-30): (20-30): (5-15): (10-20): (5-10): (6-12): (5-10) nickel salt, sodium hypophosphite, sodium acetate, citric acid compound, malic acid, lactic acid and sodium succinate
Compared with the prior art, the invention has the following beneficial effects:
1. the method adopts silanization treatment and then activation, the metal layer and the nonmetal layer in the hole of the aluminum substrate form an active center in the nickel plating solution, the active center and the surface of the metal layer and the nonmetal layer have strong adsorption capacity, the problem of plating leakage can be well avoided, the chemical nickel plating and activation efficiency can be greatly improved, the plating is started quickly, and the plating layer is uniform and compact;
2. compared with the conventional method for metallizing the aluminum alloy, which is a zinc dipping method, the conventional method for metallizing the aluminum alloy cannot realize metallizing on resin, and the conventional method for metallizing the holes of the substrate can cause serious corrosion of the aluminum layers in the holes and influence the bonding force of subsequent coatings.
3. The method has small corrosivity on the aluminum alloy layer of the PCB aluminum substrate, thereby ensuring that the metalized coating has good smoothness.
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FIG. 1 is a process flow diagram of a method for synchronously metallizing a metal layer and a non-metal layer in a hole of a PCB aluminum substrate provided by the present invention;
Detailed Description
The present invention is further illustrated with reference to the following specific examples, which should not be construed as limiting the scope of the invention.
In order to better reflect the synchronous metallization of the metal layer and the nonmetal layer in the hole of the PCB aluminum substrate, the following embodiments 1 to 5 adopt an aluminum alloy layer and an epoxy resin layer to respectively represent the structure of the metal layer and the nonmetal layer in the hole of the aluminum substrate, and the process flow diagram is shown in fig. 1.
Example 1
The following solutions were prepared:
1. the preparation method comprises the following steps of (1) preparing an alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: after 10g of sodium hydroxide, 20g of sodium carbonate and 10g of sodium phosphate are dissolved in water, the mixture is mixed and stirred evenly to prepare 1 liter of alkaline degreasing fluid.
2. Preparing an alkaline etching solution: weighing 50g of sodium hydroxide, adding into 500ml of deionized water, stirring while adding, uniformly stirring after adding, and finally adding deionized water to a constant volume of 1L to obtain the alkali etching solution.
3. Preparing a silane liquid, wherein the silane liquid comprises the following components: the silane coupling agent, the stabilizer and the accelerator are in a mass ratio of 1-5: 0.1-10: 0.1-1, the stabilizer is alcohol or/and a surfactant, and the concentration of the stabilizer is 1-100 ml/L. In this example, the concentration of the silane coupling agent was 30ml/L, the stabilizer was 50ml/L ethanol, and the accelerator was 2ml/L ammonia water.
4. The preparation of the activating solution comprises 30-50 ppm of palladium chloride, 1-100 ml/L of hydrochloric acid and 10-1000 ppm of ammonium chloride, in this example, 50mg of palladium chloride, 1ml of hydrochloric acid (37% concentration) and 10mg of ammonium chloride are dissolved in water and then mixed uniformly to prepare 1L of activating solution.
5. Preparing a nickel plating solution, wherein the nickel plating solution comprises the following components in percentage by mass (15-30): (20-30): (5-15): (10-20): (5-10): (6-12): (5-10) nickel salt, sodium hypophosphite, sodium acetate, citric acid compounds, malic acid, lactic acid and sodium succinate; the nickel salt is one or more of nickel sulfate, nickel chloride, nickel hypophosphite or nickel nitrate; the citric acid compound is citric acid or/and sodium salt of citric acid. In the embodiment, 20g/L nickel sulfate, 20g/L sodium hypophosphite, 5g/L anhydrous sodium acetate, 6ml/L lactic acid, 10g/L sodium citrate, 5g/L malic acid and 5g/L sodium succinate are adopted.
In this embodiment, the method of the present invention sequentially includes the following steps:
(1) placing the aluminum substrate in alkaline degreasing fluid, namely simultaneously placing the metal layer and the nonmetal layer in the alkaline degreasing fluid, degreasing the hole of the aluminum substrate, removing an oxide film on the surface of the metal layer in the hole for 5min, wherein the temperature of the alkaline degreasing fluid is 50 ℃, and then fully washing with deionized water;
(2) placing the degreased aluminum substrate into an alkaline etching solution for etching for 30s at the temperature of 50 ℃, and then fully washing with deionized water;
(3) placing the aluminum substrate into silane liquid for silanization, wherein the silanization time is 60s, the temperature of the silane liquid is 50 ℃, and then fully washing with deionized water;
(4) placing the silanized aluminum substrate into an oven for baking and curing, wherein the baking and curing time is 2min, the baking and curing temperature is 80 ℃, and then fully washing with deionized water;
(5) putting the baked and cured aluminum substrate into an activating solution for activating, wherein the activating time is 60s, the temperature of the activating solution is 25 ℃, and then fully washing with deionized water;
(6) and putting the activated aluminum substrate into a nickel plating solution for metallization, wherein the reaction time of nickel plating is 10min, and the temperature of the nickel plating solution is 80 ℃, so that a nickel plating product is obtained, and the synchronous metallization of the metal layer and the nonmetal layer is realized.
Example 2
The following solutions were prepared:
1. the preparation method of the alkaline degreasing fluid comprises the steps of dissolving 20g of sodium hydroxide, 20g of sodium carbonate and 8g of sodium phosphate in water, mixing and stirring uniformly to prepare 1L of the alkaline degreasing fluid.
2. Preparing an alkaline etching solution: weighing 40g of sodium hydroxide, adding into 500ml of deionized water, stirring while adding, uniformly stirring after adding, and finally adding deionized water to a constant volume of 1L to obtain the alkali etching solution.
3. Preparing a silane liquid, wherein the silane liquid comprises the following components: the silane coupling agent, the stabilizer and the accelerator are in a mass ratio of 1-5: 0.1-10: 0.1-1, the stabilizer is alcohol or/and a surfactant, and the concentration of the stabilizer is 1-100 ml/L. In this example, the concentration of the silane coupling agent was 20ml/L, the stabilizer was 40ml/L ethanol and 1ml/L octylphenol polyoxyethylene ether (OP-10), and the accelerator was 0.2g/L sodium hydroxide.
4. The preparation of the activating solution comprises 30-50 ppm of palladium chloride, 1-100 ml/L of hydrochloric acid and 10-1000 ppm of ammonium chloride, in this example, 40mg of palladium chloride, 1ml of hydrochloric acid (37% concentration) and 10mg of ammonium chloride are dissolved in water and then mixed uniformly to prepare 1 liter of activating solution.
5. Preparing a nickel plating solution, wherein the nickel plating solution comprises the following components in percentage by mass (15-30): (20-30): (5-15): (10-20): (5-10): (6-12): (5-10) nickel salt, sodium hypophosphite, sodium acetate, citric acid compounds, malic acid, lactic acid and sodium succinate, wherein the nickel salt is one or more of nickel sulfate, nickel chloride, nickel hypophosphite or nickel nitrate; the citric acid compound is citric acid or/and sodium salt of citric acid. In the embodiment, 25g/L nickel sulfate, 25g/L sodium hypophosphite, 7g/L anhydrous sodium acetate, 8ml/L lactic acid, 12g/L sodium citrate, 5g/L malic acid and 7g/L sodium succinate are adopted.
In this embodiment, the method of the present invention sequentially includes the following steps:
(1) placing the aluminum substrate in alkaline degreasing fluid, namely simultaneously placing the metal layer and the nonmetal layer in the alkaline degreasing fluid, degreasing the hole of the aluminum substrate, removing an oxide film on the surface of the metal layer in the hole for 3min, wherein the temperature of the alkaline degreasing fluid is 60 ℃, and then fully washing with deionized water;
(2) placing the degreased aluminum substrate into an alkaline etching solution for etching, wherein the etching time is 60s, the temperature of the etching solution is 60 ℃, and then, fully washing the aluminum substrate with deionized water;
(3) placing the aluminum substrate into silane liquid for silanization, wherein the silanization time is 90s, the temperature of the silane liquid is 60 ℃, and then fully washing with deionized water;
(4) placing the silanized aluminum substrate into an oven for baking and curing, wherein the baking and curing time is 5min, the baking and curing temperature is 100 ℃, and then fully washing with deionized water;
(5) putting the baked and cured aluminum substrate into an activating solution for activating, wherein the activating time is 60s, the temperature of the activating solution is 25 ℃, and then fully washing with deionized water;
(6) and putting the activated aluminum substrate into a nickel plating solution for metallization, wherein the reaction time of nickel plating is 10min, and the temperature of the nickel plating solution is 80 ℃, so that a nickel plating product is obtained, and the synchronous metallization of the metal layer and the nonmetal layer is realized.
Example 3
The following solutions were prepared:
1. the preparation method comprises the following steps of (1) preparing an alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 15g of sodium hydroxide, 15g of sodium carbonate and 5g of sodium phosphate are dissolved in water and then are mixed and stirred uniformly to prepare 1 liter of alkaline degreasing fluid.
2. Preparing an alkaline etching solution: weighing 30g of sodium hydroxide, adding into 500ml of deionized water, stirring while adding, uniformly stirring after all adding, and finally adding deionized water to a constant volume of 1L to obtain the alkali etching solution.
3. Preparing a silane liquid, wherein the silane liquid comprises the following components: the silane coupling agent, the stabilizer and the accelerator are in a mass ratio of 1-5: 0.1-10: 0.1-1, the stabilizer is alcohol or/and a surfactant, and the concentration of the stabilizer is 1-100 ml/L. In this example, the concentration of the silane coupling agent was 30ml/L, the surfactant was 10ml/L of polyethylene glycol, and the accelerator was 0.1g/L of sodium hydroxide.
4. The preparation method comprises the steps of preparing an activating solution, wherein the activating solution comprises 30-50 ppm of palladium chloride, 1-100 ml/L of hydrochloric acid and 10-1000 ppm of ammonium chloride, and in the embodiment, 50mg of palladium chloride, 1ml of hydrochloric acid (with the concentration of 37%) and 20mg of ammonium chloride are dissolved in water and then uniformly mixed to prepare 1 liter of the activating solution.
5. Preparing a nickel plating solution, wherein the nickel plating solution comprises the following components in percentage by mass (15-30): (20-30): (5-15): (10-20): (5-10): (6-12): (5-10) nickel salt, sodium hypophosphite, sodium acetate, citric acid compounds, malic acid, lactic acid and sodium succinate, wherein the nickel salt is one or more of nickel sulfate, nickel chloride, nickel hypophosphite or nickel nitrate; the citric acid compound is citric acid or/and sodium salt of citric acid. In the embodiment, 20g/L nickel sulfate, 25g/L sodium hypophosphite, 5g/L anhydrous sodium acetate, 8ml/L lactic acid, 10g/L sodium citrate, 5g/L malic acid and 5g/L sodium succinate are adopted.
In this embodiment, the method of the present invention sequentially includes the following steps:
(1) placing the aluminum substrate in alkaline degreasing fluid, namely simultaneously placing the metal layer and the nonmetal layer in the alkaline degreasing fluid, degreasing the hole of the aluminum substrate, removing an oxide film on the surface of the metal layer in the hole for 5min, wherein the temperature of the alkaline degreasing fluid is 70 ℃, and then fully washing with deionized water;
(2) placing the degreased aluminum substrate into an alkaline etching solution for etching, wherein the etching time is 20s, the temperature of the etching solution is 50 ℃, and then, fully washing the aluminum substrate with deionized water;
(3) placing the aluminum substrate into silane liquid for silanization, wherein the silanization time is 120s, the temperature of the silane liquid is 50 ℃, and then fully washing with deionized water;
(4) placing the silanized aluminum substrate into an oven for baking and curing, wherein the baking and curing time is 2min, the baking and curing temperature is 100 ℃, and then fully washing with deionized water;
(5) putting the baked and cured aluminum substrate into an activating solution for activating for 30s at 25 ℃, and then fully washing with deionized water;
(6) and putting the activated aluminum substrate into a nickel plating solution for metallization, wherein the reaction time of nickel plating is 15min, and the temperature of the nickel plating solution is 80 ℃, so that a nickel plating product is obtained, and the synchronous metallization of the metal layer and the nonmetal layer is realized.
Example 4
The following solutions were prepared:
1. the preparation method comprises the following steps of (1) preparing an alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 50g of sodium hydroxide, 10g of sodium carbonate and 5g of sodium phosphate are dissolved in water and then are mixed and stirred uniformly to prepare 1 liter of alkaline degreasing fluid.
2. Preparing an alkaline etching solution: and weighing 30g of sodium hydroxide and 10g of potassium hydroxide, adding into 500ml of deionized water while stirring, uniformly stirring after all the sodium hydroxide and the potassium hydroxide are added, and finally adding deionized water to a constant volume of 1L to obtain the alkali etching solution.
3. Preparing a silane liquid, wherein the silane liquid comprises the following components: the silane coupling agent, the stabilizer and the accelerator are in a mass ratio of 1-5: 0.1-10: 0.1-1, the stabilizer is alcohol or/and a surfactant, and the concentration of the stabilizer is 1-100 ml/L. In this example, the concentration of the silane coupling agent was 30ml/L, the stabilizer was 20ml/L of methanol and 20ml/L of propanol, and the accelerator was 8g/L of sodium carbonate and 10g/L of sodium bicarbonate.
4. The preparation of the activating solution comprises 30-50 ppm of palladium chloride, 1-100 ml/L of hydrochloric acid and 10-1000 ppm of ammonium chloride, in this example, 50mg of palladium chloride, 1ml of hydrochloric acid (37% concentration) and 20mg of ammonium chloride are dissolved in water and then mixed uniformly to prepare 1 liter of activating solution.
5. Preparing a nickel plating solution, wherein the nickel plating solution comprises the following components in percentage by mass (15-30): (20-30): (5-15): (10-20): (5-10): (6-12): (5-10) nickel salt, sodium hypophosphite, sodium acetate, citric acid compounds, malic acid, lactic acid and sodium succinate; the nickel salt is one or more of nickel sulfate, nickel chloride, nickel hypophosphite or nickel nitrate; the citric acid compound is citric acid or/and sodium salt of citric acid. In the embodiment, 20g/L nickel sulfate, 25g/L sodium hypophosphite, 5g/L anhydrous sodium acetate, 8ml/L lactic acid, 10g/L sodium citrate, 5g/L malic acid and 5g/L sodium succinate are adopted.
In this embodiment, the method of the present invention sequentially includes the following steps:
(1) placing the aluminum substrate in alkaline degreasing fluid, namely simultaneously placing the metal layer and the nonmetal layer in the alkaline degreasing fluid, degreasing the hole of the aluminum substrate, removing an oxide film on the surface of the metal layer in the hole for 6min, wherein the temperature of the alkaline degreasing fluid is 30 ℃, and then fully washing with deionized water;
(2) placing the degreased aluminum substrate into an alkaline etching solution for etching, wherein the etching time is 10s, the temperature of the etching solution is 80 ℃, and then, fully washing with deionized water;
(3) placing the aluminum substrate into silane liquid for silanization, wherein the silanization time is 10s, the temperature of the silane liquid is 70 ℃, and then fully washing with deionized water;
(4) placing the silanized aluminum substrate into an oven for baking and curing, wherein the baking and curing time is 5min, the baking and curing temperature is 50 ℃, and then fully washing with deionized water;
(5) putting the baked and cured aluminum substrate into an activating solution for activating for 100s at the temperature of 50 ℃, and then fully washing with deionized water;
(6) and putting the activated aluminum substrate into a nickel plating solution for metallization, wherein the reaction time of nickel plating is 12min, and the temperature of the nickel plating solution is 70 ℃, so that a nickel plating product is obtained, and the synchronous metallization of the metal layer and the nonmetal layer is realized.
Example 5
The following solutions were prepared:
1. the preparation method comprises the following steps of (1) preparing an alkaline degreasing liquid, wherein the alkaline degreasing liquid comprises the following components: 25g of sodium hydroxide, 50g of sodium carbonate and 10g of sodium phosphate are dissolved in water and then mixed and stirred uniformly to prepare 1 liter of alkaline degreasing fluid.
2. Preparing an alkaline etching solution: weighing 40g of potassium hydroxide, adding into 500ml of deionized water, stirring while adding, uniformly stirring after adding, and finally adding deionized water to a constant volume of 1L to obtain the alkali etching solution.
3. Preparing a silane liquid, wherein the silane liquid comprises the following components: the silane coupling agent, the stabilizer and the accelerator are in a mass ratio of 1-5: 0.1-10: 0.1-1, the stabilizer is alcohol or/and a surfactant, and the concentration of the stabilizer is 1-100 ml/L. In this example, the concentration of the silane coupling agent was 25ml/L, the stabilizer was 30ml/L sodium lauryl sulfate, and the accelerators were 0.2g/L potassium hydroxide and 0.3g/L sodium acetate.
4. The preparation of the activating solution comprises 30-50 ppm of palladium chloride, 1-100 ml/L of hydrochloric acid and 10-1000 ppm of ammonium chloride, in this example, 30mg of palladium chloride, 1ml of hydrochloric acid (37% concentration) and 15mg of ammonium chloride are dissolved in water and then mixed uniformly to prepare 1 liter of activating solution.
5. Preparing a nickel plating solution, wherein the nickel plating solution comprises the following components in percentage by mass (15-30): (20-30): (5-15): (10-20): (5-10): (6-12): (5-10) nickel salt, sodium hypophosphite, sodium acetate, citric acid compounds, malic acid, lactic acid and sodium succinate; the nickel salt is one or more of nickel sulfate, nickel chloride, nickel hypophosphite or nickel nitrate; the citric acid compound is citric acid or/and sodium salt of citric acid. In the embodiment, 22g/L nickel sulfate, 25g/L sodium hypophosphite, 6g/L anhydrous sodium acetate, 8ml/L lactic acid, 11g/L sodium citrate, 5g/L malic acid and 6g/L sodium succinate are adopted.
In this embodiment, the method of the present invention sequentially includes the following steps:
(1) placing the aluminum substrate in alkaline degreasing fluid, namely simultaneously placing the metal layer and the nonmetal layer in the alkaline degreasing fluid, degreasing the hole of the aluminum substrate, removing an oxide film on the surface of the metal layer in the hole for 4min, wherein the temperature of the alkaline degreasing fluid is 80 ℃, and then fully washing with deionized water;
(2) placing the degreased aluminum substrate into an alkaline etching solution for etching, wherein the etching time is 100s, the temperature of the etching solution is 20 ℃, and then, fully washing the aluminum substrate with deionized water;
(3) placing the aluminum substrate into silane liquid for silanization, wherein the silanization time is 110s, the temperature of the silane liquid is 0 ℃, and then fully washing with deionized water;
(4) placing the silanized aluminum substrate into an oven for baking and curing, wherein the baking and curing time is 1min, the baking and curing temperature is 120 ℃, and then fully washing with deionized water;
(5) putting the baked and cured aluminum substrate into an activating solution for activating, wherein the activating time is 120s, the temperature of the activating solution is 20 ℃, and then, fully washing the aluminum substrate with deionized water;
(6) and putting the activated aluminum substrate into a nickel plating solution for metallization, wherein the reaction time of nickel plating is 5min, and the temperature of the nickel plating solution is 90 ℃, so that a nickel plating product is obtained, and the synchronous metallization of the metal layer and the nonmetal layer is realized.
The nickel-plated product is obtained by the method of the above embodiments 1 to 5, and by observing the metallographic microscopic image of the cross section in the hole, it can be found that the resin layer and the aluminum alloy layer in the hole are both provided with the nickel-plated layer, and the nickel-plated layer is free from separation and crushing, which indicates that the bonding force between the nickel-plated layer on the hole wall and the aluminum substrate is good, and the metal layer and the nonmetal layer in the hole of the PCB aluminum substrate are synchronously metallized.
According to the test method of the adhesion strength of metal covering layers (an electro-deposition layer and a chemical deposition layer) on a metal matrix of GB-5270-85, the nickel-plated product obtained by the process is subjected to a scratch test method for three times and a thermal shock test, and the test results are shown in the following table:
the aluminum substrate is degreased in order to remove organic grease on the surface of the aluminum substrate and an oxide film of an aluminum alloy layer in a hole, the organic grease may be engine oil attached to the surface of the aluminum substrate in the production and transportation processes or residue of fingerprints of workers, the organic grease can affect the binding force between a subsequent plating layer and the aluminum substrate, and the organic grease must be completely removed before being put into a nickel plating solution; the surface oxide film is the particularity that aluminum is easy to oxidize in air to generate a loose oxide film, so that the aluminum substrate has poor corrosion resistance and the performance of a plating layer is seriously influenced.
According to the invention, the aluminum substrate is subjected to silanization treatment, a layer of silane film is generated on the surface of the metal layer and the non-metal layer in the hole of the aluminum substrate, then the aluminum substrate is put into activating solution for activation treatment, and then chemical nickel plating is carried out, so that the metal layer and the non-metal layer in the hole are synchronously metalized, and a compact nickel plating layer is obtained. The main principle is as follows: the silane solution contains a silane coupling agent, the molecule of the silane coupling agent contains two different reactive groups, the chemical structure of the silane coupling agent can be represented by Y-R-SiX3, the reaction characteristics of X and Y are different, X is a group which is combined on a silicon atom and can carry out hydrolysis reaction to generate silicon hydroxyl (Si-OH), Y is an organic functional group, such as amino, epoxy, vinyl, hydrophobic group and the like, and the organic functional group can be complexed with some metal ions, so that the metal ions are adsorbed on the surface. When the aluminum alloy and the epoxy resin are put into the silane liquid, as the silane coupling agent in the silane liquid generates hydrolysis and condensation reaction to generate silicon hydroxyl (Si-OH), the surfaces of the aluminum alloy and the epoxy resin contain more hydroxyl-OH, the Si-OH in the solution is linked with the hydroxyl-OH on the surface of the aluminum substrate to form hydrogen bonds, and then the hydrogen bonds are connected with the aluminum substrate along with dehydration reaction through heating, baking and curing, so that a layer of silane film is formed on the surfaces of the aluminum alloy and the resin, and the bonding force is good. X in the silane coupling agent Y-R-SiX3 forms a covalent bond with an aluminum substrate, Y groups are hung at the outer end, the widely used Y groups are amino groups, the amino groups have the capability of being easily complexed with some metal ions, and metal ions such as Pd2+, by utilizing the characteristic, an aluminum alloy layer and a resin layer after silanization are put into palladium activation solution, the amino groups on the silane film are easily complexed with Pd in the palladium activation solution, so that the palladium ions are attached to the surface of the aluminum substrate, and react with a reducing agent in nickel plating solution to generate palladium atoms, thereby forming an active center, and then catalyzing chemical nickel plating reaction, thereby synchronously metallizing the metal layer of the aluminum alloy and the nonmetal layer of the epoxy resin, and further obtaining a nickel plating layer.
The invention provides a method for synchronously metallizing a metal layer and a nonmetal layer in a hole of a PCB aluminum substrate, which adopts silanization treatment and activation, can well avoid the problem of plating leakage, can greatly improve the efficiency of chemical nickel plating and activation, and has the advantages of quick plating start and uniform and compact plating layer; the method has simple process, reduces the production cost, can well realize the synchronous metallization of the inner metal layer and the nonmetal layer of the hole of the PCB aluminum substrate, and the obtained plating layer has good bonding force with the hole wall; the method has small corrosivity on the aluminum alloy layer of the PCB aluminum substrate, thereby ensuring that the metalized coating has good smoothness.
The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. It will be apparent to those skilled in the art that other variations and modifications may be made in the foregoing description, and it is not necessary or necessary to exhaustively enumerate all embodiments herein. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. A method for synchronously metalizing a metal layer and a nonmetal layer in a hole of a PCB aluminum substrate is characterized by comprising the following steps: the method comprises the following steps:
s1: placing the aluminum substrate in alkaline degreasing fluid, performing degreasing treatment in the hole of the aluminum substrate, and removing an oxide film on the surface of a metal layer in the hole;
s2: placing the aluminum substrate processed in the step S1 into an alkaline etching solution for etching;
s3: placing the aluminum substrate processed in the step S2 into silane liquid for silanization;
s4: placing the aluminum substrate processed in the step S3 into an oven for baking and curing;
s5: putting the aluminum substrate processed in the step S4 into an activating solution for activation;
s6: putting the aluminum substrate processed in the step S5 into a nickel plating solution for metallization to obtain a nickel plated product;
the silane liquid comprises a silane coupling agent, a stabilizer and an accelerator in a mass ratio of 1-5: 0.1-10: 0.1-1.
2. The method of claim 1, wherein the method comprises the steps of: the accelerant is one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium acetate, sodium carbonate and sodium bicarbonate.
3. The method of claim 1, wherein the method comprises the steps of: the stabilizing agent is alcohol and/or a surfactant, and the concentration of the stabilizing agent is 1-100 ml/L.
4. The method of claim 3, wherein the method comprises the steps of: the alcohol is one or more of methanol, ethanol and propanol; the surfactant is one or more of polyethylene glycol, octyl phenol polyoxyethylene ether and lauryl sodium sulfate.
5. The method of claim 1, wherein the method comprises the steps of: the temperature of the silane liquid is 0-70 ℃, the silanization time is 10-120 s, the baking curing temperature is 50-120 ℃, and the baking curing time is 1-5 min.
6. The method of claim 1, wherein the method comprises the steps of: the alkaline degreasing fluid comprises sodium phosphate, sodium carbonate and sodium hydroxide, wherein the concentration of the sodium phosphate is 10-50 g/L, the concentration of the sodium carbonate is 10-50 g/L, and the concentration of the sodium hydroxide is 5-10 g/L.
7. The method of claim 1, wherein the method comprises the steps of: the alkali etching solution is one or two of sodium hydroxide or potassium hydroxide, and the concentration of the alkali etching solution is 10-100 g/L.
8. The method of claim 1, wherein the method comprises the steps of: the activating solution comprises palladium chloride, hydrochloric acid and ammonium chloride, wherein the concentration of the palladium chloride is 30-500 ppm, the concentration of the hydrochloric acid is 1-100 ml/L, and the concentration of the ammonium chloride is 10-1000 ppm.
9. The method of claim 1, wherein the method comprises the steps of: the temperature of the alkaline degreasing liquid is 30-80 ℃, and the time of degreasing treatment is 3-6 min; the temperature of the alkali etching solution is 20-80 ℃, and the etching time is 10-100 s; the temperature of the activation solution is 20-50 ℃, and the activation time is 30-120 s; the temperature of the nickel plating solution is 70-90 ℃, and the nickel plating time is 5-15 min; the baking curing temperature is 50-120 ℃, and the baking curing time is 1-5 min.
10. The method of claim 1, wherein the method comprises the steps of: the nickel plating solution comprises the following components: the mass ratio is (15-30): (20-30): (5-15): (10-20): (5-10): (6-12): (5-10) nickel salt, sodium hypophosphite, sodium acetate, citric acid compounds, malic acid, lactic acid and sodium succinate.
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| CN202011288123.1A CN112469209B (en) | 2020-11-17 | 2020-11-17 | Method for synchronously metalizing metal layer and nonmetal layer in hole of PCB (printed circuit board) |
| PCT/CN2020/134593 WO2022104942A1 (en) | 2020-11-17 | 2020-12-08 | Method for synchronizing metallization of metal layer and non-metal layer in hole of pcb aluminum substrate |
| JP2022515939A JP7285370B2 (en) | 2020-11-17 | 2020-12-08 | Method for synchronous metallization of metallic and non-metallic layers in PCB aluminum substrate holes |
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| US5753304A (en) * | 1997-06-23 | 1998-05-19 | The Metal Arts Company, Inc. | Activation bath for electroless nickel plating |
| CN104928658A (en) * | 2015-05-13 | 2015-09-23 | 电子科技大学 | Method for activating circuit surface of PCB (printed circuit board) to realize electroless nickel plating |
| CN109898115A (en) * | 2019-03-25 | 2019-06-18 | 广东工业大学 | Electro-coppering pre-treating method on a kind of quick aluminum substrate |
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| JP5566921B2 (en) * | 2011-01-17 | 2014-08-06 | 名東電産株式会社 | Method for manufacturing printed wiring board using aluminum as conductive pattern |
| JP6225047B2 (en) * | 2014-03-06 | 2017-11-01 | 名東電産株式会社 | Printed wiring board using aluminum as conductive pattern, and manufacturing method thereof |
| US9875984B2 (en) * | 2014-12-05 | 2018-01-23 | National Tsing Hua University | Substrate surface metallization method and substrate having metallized surface manufactured by the same |
| CN105050324B (en) * | 2015-07-01 | 2018-06-12 | 广东光华科技股份有限公司 | Copper surface roughening treatment liquid and its processing method |
| CN111334784B (en) * | 2020-04-15 | 2022-08-05 | 深圳市欣茂鑫实业有限公司 | Nickel plating process for aluminum alloy surface |
| CN111763930B (en) * | 2020-07-14 | 2022-04-19 | 赤壁市聚茂新材料科技有限公司 | Non-palladium activated copper plating process and sensitizer and activator thereof |
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| US5753304A (en) * | 1997-06-23 | 1998-05-19 | The Metal Arts Company, Inc. | Activation bath for electroless nickel plating |
| CN104928658A (en) * | 2015-05-13 | 2015-09-23 | 电子科技大学 | Method for activating circuit surface of PCB (printed circuit board) to realize electroless nickel plating |
| CN109898115A (en) * | 2019-03-25 | 2019-06-18 | 广东工业大学 | Electro-coppering pre-treating method on a kind of quick aluminum substrate |
| CN109989078A (en) * | 2019-03-25 | 2019-07-09 | 广东工业大学 | A kind of method of the Ag activation method and electro-coppering of electro-coppering pre-treatment on aluminium base |
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| WO2022104942A1 (en) | 2022-05-27 |
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