CN115896762A - Palladium-free activation chemical copper deposition process for resin substrate - Google Patents

Abstract

The invention relates to a resin substrate-free palladium-activated electroless copper deposition process, which comprises the following steps: (1) sequentially performing degreasing treatment and roughening treatment on the resin substrate to obtain a pretreated resin substrate; (2) pretreatment Immerse the resin substrate in the pyrrole solution for a period of time, then immerse the resin substrate in the ferric chloride solution, and let it stand for a period of time to obtain a substrate with a polypyrrole film. Place the substrate with the polypyrrole film in a boiling water bath above, fumigate the substrate with the polypyrrole film with water vapor, and then wash to obtain an activated substrate; (3) immerse the activated substrate in an electroless copper deposition solution for electroless copper deposition to obtain an electroless copper plating layer. Compared with the prior art, the present invention uses pyrrole-loaded colloidal iron as the catalytic active site of electroless copper plating, realizes electroless copper deposition on the surface of non-conductive plastic substrates, replaces the use of precious metals, and solves the difficult problem of precious metal catalytic reaction waste liquid problems and reduce production costs.

Description

A Resin Substrate Palladium-Free Activation Chemical Copper Precipitation Process

technical field

The invention belongs to the technical field of non-metallic surface treatment, and relates to a palladium-free activation electroless copper deposition process for a resin substrate.

Background technique

With the continuous development of the information society, printed circuit board (Printed Circuit Board, PCB) has become an essential part of modern electronic equipment, and is developing towards the trend of light, thin, short and small, so the integration of electronic products is getting higher and higher , Therefore, the application of high-density interconnection circuit boards and multilayer boards is becoming more and more extensive, and the technical requirements for interconnection between circuit board layers are also getting higher and higher. Hole metallization is the key technology for circuit board interconnection, and electroless copper plating technology has become the mainstream of printed circuit board hole metallization due to its excellent coating performance, high bonding strength, wear resistance, corrosion resistance, and simple process. The metallization of the surface of the traditional plastic substrate, that is, electroless copper deposition, requires the use of precious metals such as gold and palladium to catalyze and activate the surface of the non-conductive substrate, so that the copper ions in the copper deposition solution form a copper metal layer with self-catalytic ability on the surface of the substrate. The use of precious metals such as gold and palladium also increases production costs, and precious metal catalytic reaction waste liquid is difficult to handle, so finding new palladium-free activation methods has become a research hotspot in the prior art.

Contents of the invention

The purpose of the present invention is to provide a palladium-free activated electroless copper deposition process for resin substrates, so as to overcome the following defects in the prior art: electroless copper deposition on the surface of plastic substrates requires the use of gold, palladium and other precious metals to carry out catalytic activation treatment on the surface of non-conductive substrates , increase the production cost, or the precious metal catalytic reaction waste liquid produced is difficult to handle.

The purpose of the present invention can be achieved through the following technical solutions:

A resin substrate-free palladium-activated electroless copper deposition process, comprising the following steps:

(1) performing degreasing treatment and roughening treatment on the resin substrate in sequence to obtain a pretreated resin substrate;

(2) Immerse the obtained pretreated resin substrate in the pyrrole solution, soak for a period of time, then immerse the resin substrate in the ferric chloride solution, and let it stand for a period of time to obtain a substrate with a polypyrrole film. The substrate is placed above the boiling water, so that the water vapor fumigates the substrate with the polypyrrole film, and then the activated substrate is obtained by washing;

(3) Immersing the obtained activated substrate into an electroless copper deposition solution to perform electroless copper deposition to obtain an electroless copper plating layer.

Further, in step (1), the specific process of oil removal treatment is:

The resin substrate is immersed in an alkaline degreasing solution for a period of time, and then washed to complete the degreasing treatment.

Furthermore, during the soaking process, the temperature of the alkaline degreasing solution is 60°C.

Furthermore, the soaking time is 5 minutes.

Furthermore, the components of the alkaline degreasing solution include sodium hydroxide 30g/L, sodium phosphate 50g/L, sodium carbonate 30g/L and OP-10 10ml/L.

Further, in step (1), the specific process of coarsening processing is:

The resin substrate that has undergone degreasing treatment is immersed in an acidic roughening solution for a period of time, and then washed to complete the roughening treatment.

Furthermore, during the soaking process, the temperature of the acidic roughening solution is 70°C.

Furthermore, the soaking time is 3 minutes.

Furthermore, the components of the acidic roughening solution include potassium permanganate 80g/L and sodium hydroxide 40g/L.

Further, in step (2), the pyrrole solution is an ethanol solution of pyrrole, wherein the volume ratio of pyrrole to ethanol is 1:(1-3).

Further, in step (2), the soaking time in the pyrrole solution is 1-10 minutes.

Further, in step (2), the concentration of the ferric chloride solution is 0.5-2mol/L.

Further, in step (2), the standing time is 10-30 minutes. After standing still, a polypyrrole film will be formed on the surface of the resin substrate.

Further, in step (2), the fumigation time is 0.5-2h. After fumigation, colloidal iron is loaded on the resin substrate, and then cleaned with deionized water before use.

Further, in step (3), the components of the chemical copper precipitation solution include potassium sodium tartrate 80g/L, sodium hydroxide 15g/L, sodium carbonate 7g/L, potassium sodium tartrate 8g/L, copper sulfate pentahydrate 20g/L L, nickel chloride 2g/L and formaldehyde 37% 30ml/L.

Further, in step (3), the electroless copper precipitation time is 1-4h. A uniform copper layer with good bonding force is prepared by electroless copper deposition. The copper layer has good conductivity and can be used as a conductive layer for subsequent copper layer electroplating.

The invention provides a resin substrate palladium-free activated chemical precipitation copper process, which solves the high cost of using precious metal palladium as the activation raw material and the pollution caused by waste liquid discharge in the prior art, and at the same time covers a layer of dense copper on the surface of the substrate. Continuous electroless copper layer.

The palladium-free activated chemical copper plating process on the surface of resin substrates provided by the present invention uses ferric iron instead of traditional precious metal palladium to catalyze the surface of the substrate, and does not use precious metal palladium, which solves the difficult problem of palladium-containing waste liquid and reduces production costs. cost. The invention adopts an activation process to obtain many active sites on the surface and evenly distributed activation sites, and obtains a smooth and dense plating layer after electroless copper plating.

Through the implementation of degreasing in the steps of the present invention, the surface of the substrate is free from oil stains, which is conducive to the contact of subsequent chemical substances with the surface of the substrate. The implementation of roughening treatment can increase the specific surface area of the substrate to an appropriate degree, and improve the adhesion of subsequent attachments to the substrate. The contact area can improve the bonding force between the subsequent film layer and the substrate. After degreasing and roughening, the surface of the substrate should have a good ability to contact the aqueous solution and the contact area between the film layer and the substrate. This pretreatment operation is conducive to the full contact of pyrrole molecules with the substrate. Since the interaction between molecules and substrates is a dynamic process, it is necessary to have enough soaking time to achieve the maximum adsorption of molecules on the substrate surface and to achieve the film formation of subsequent reactions. valid quantity. The film formation of pyrrole needs to be completed by the oxidation of ferric iron. Therefore, the concentration and time of ferric chloride determine the oxidation speed and degree of oxidation of the pyrrole oxide film. Polypyrrole membrane with suitable molecular chain length to absorb and accommodate ferric ions. The process of water molecule fumigation realizes the colloidal transformation of ferric iron, making it more securely fixed in the framework of polypyrrole long-chain molecules, and becomes a catalyst for the subsequent electroless copper plating reaction. Since the process of electroless copper plating has the process of nucleation formation and nucleation growth, sufficient electroless copper deposition time is conducive to the formation and growth of copper nuclei, and then forms a copper film with continuous effect. Therefore, sufficient electroless copper deposition time is necessary, but too long electroless copper deposition time will lead to excessive growth of copper, too large grains, resulting in rough coating, or even too thick coating. The experimental parameters provided by the present invention achieve the purpose of uniform copper deposition, and also achieve the purpose of obtaining an effective and uniform chemical deposition copper surface.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention directly uses pyrrole-loaded colloidal iron as the catalytic active site of electroless copper plating, realizes electroless copper deposition on the surface of non-conductive plastic substrates, replaces the use of precious metals such as palladium and silver, and solves the difficult treatment of precious metal catalytic reaction waste liquid problems, while reducing production costs;

(2) The activation process provided by the present invention is stable in operation, and there are no process operation problems such as instability of the sensitizing solution (stannous ion), the activation process is stable and reliable, the problem of failure of the activation solution is eliminated, the process stability is improved, and production is convenient Control is conducive to ensuring the quality of products.

Description of drawings

Fig. 1 is the scanning electron micrograph of the surface topography after the electroless copper deposition on the surface of the epoxy resin substrate of embodiment 1;

Fig. 2 is the X-photoelectron energy spectrum test figure of embodiment 1 sinking copper;

FIG. 3 is a scanning electron microscope image of the surface morphology of the epoxy resin substrate surface after electroless copper deposition in Example 3. FIG.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

In each of the following examples, if there is no specific raw material or processing technology, it is shown that all conventional commercially available raw material products or conventional processing technologies in the art are adopted.

Example 1:

1) Carry out degreasing treatment to FR-4 glass fiber epoxy resin board, the formula of degreasing liquid is: sodium hydroxide 30g/L, sodium phosphate 50g/L, sodium carbonate 30g/L, OP-10 10ml/L, will The epoxy resin substrate is immersed in the degreasing solution, the immersion temperature is 60°C, and the immersion time is 5min.

2) Roughen the substrate. The formula of the roughening solution is: potassium permanganate 80g/L, sodium hydroxide 40g/L, and the epoxy resin substrate is immersed in the roughening solution. The immersion temperature is 70°C and the immersion time is 3min.

3) Activate the substrate: prepare pyrrole solution: volume ratio of pyrrole to ethanol is 1:2, ferric chloride solution: 1mol/L. First place the substrate in the pyrrole solution and let it stand for 5 minutes, then put the substrate in the ferric chloride solution and let it stand for 30 minutes. After 30 minutes, take out the substrate and place it on the boiling water vapor, steam fumigation for 30 minutes, and then Transfer the substrate to deionized water to clean it.

4) After the third step of cleaning, the substrate is subjected to chemical copper precipitation treatment. In the chemical copper precipitation solution, the formula is potassium sodium tartrate 80g/L, sodium hydroxide 15g/L, sodium carbonate 7g/L; potassium sodium tartrate 8g/L, Copper sulfate pentahydrate 20g/L, nickel chloride 2g/L, formaldehyde 37% 30ml/L. The electroless copper deposition time is 4h, and a uniform red copper layer is obtained on the substrate. FIG. 1 is a scanning electron microscope image of the surface of the epoxy resin substrate in Example 1 after electroless copper deposition. It can be seen from FIG. 1 that the copper unit cells of the electroless copper deposition are evenly attached. Fig. 2 is an X-ray photoelectron spectrum test diagram of deposited copper, which confirms that the obtained substance is a copper coating.

Example 2:

1) Carry out degreasing treatment to FR-4 glass fiber epoxy resin board, the formula of degreasing liquid is: sodium hydroxide 30g/L, sodium phosphate 50g/L, sodium carbonate 30g/L, OP-10 10ml/L, will The epoxy resin substrate is immersed in the degreasing solution, the immersion temperature is 60°C, and the immersion time is 5min.

2) Roughen the substrate. The formula of the roughening solution is: potassium permanganate 80g/L, sodium hydroxide 40g/L, and the epoxy resin substrate is immersed in the roughening solution. The immersion temperature is 70°C and the immersion time is 3min.

3) Activate the substrate: prepare pyrrole solution concentration: volume ratio of pyrrole to ethanol is 1:1, ferric chloride solution: 0.5mol/L. First place the substrate in the pyrrole solution and let it stand for 1 minute, then put the substrate in the ferric chloride solution and let it stand for 20 minutes. After 20 minutes, take out the substrate and place it on the boiling water vapor, steam fumigation for 60 minutes, and then Transfer the substrate to deionized water to clean it.

4) After the third step of cleaning, the substrate is subjected to chemical copper precipitation treatment. In the chemical copper precipitation solution, the formula is potassium sodium tartrate 80g/L, sodium hydroxide 15g/L, sodium carbonate 7g/L; potassium sodium tartrate 8g/L, Copper sulfate pentahydrate 20g/L, nickel chloride 2g/L, formaldehyde 37% 30ml/L. The electroless copper deposition time is 2 hours, and a uniform red copper layer is obtained on the substrate.

Example 3:

1) Carry out degreasing treatment to FR-4 glass fiber epoxy resin board, the formula of degreasing liquid is: sodium hydroxide 30g/L, sodium phosphate 50g/L, sodium carbonate 30g/L, OP-10 10ml/L, will The epoxy resin substrate is immersed in the degreasing solution, the immersion temperature is 60°C, and the immersion time is 5min.

2) Roughen the substrate, the formula of the roughening solution is: potassium permanganate 80g/L, sodium hydroxide 40g/L, immerse the substrate in the roughening solution, the immersion temperature is 70°C, and the immersion time is 3min.

3) Activate the substrate: prepare pyrrole solution concentration: volume ratio of pyrrole to ethanol is 1:3, ferric chloride solution: 2mol/L. First place the substrate in the pyrrole solution and let it stand for 10 minutes, then put the substrate in the ferric chloride solution and let it stand for 10 minutes. After 10 minutes, take out the substrate and place it on the boiling water vapor, steam fumigation for 2 hours, and then Transfer the substrate to deionized water to clean it.

4) After the third step of cleaning, the substrate is subjected to chemical copper precipitation treatment. In the chemical copper precipitation solution, the formula is potassium sodium tartrate 80g/L, sodium hydroxide 15g/L, sodium carbonate 7g/L; potassium sodium tartrate 8g/L, Copper sulfate pentahydrate 20g/L, nickel chloride 2g/L, formaldehyde 37% 30ml/L. The electroless copper deposition time is 1h, and a uniform red copper layer is obtained on the substrate. As shown in Figure 3, the unit cells on the substrate surface are stacked.

Example 4:

1) Carry out degreasing treatment to FR-4 glass fiber epoxy resin board, the formula of degreasing liquid is: sodium hydroxide 30g/L, sodium phosphate 50g/L, sodium carbonate 30g/L, OP-10 10ml/L, will The epoxy resin substrate is immersed in the degreasing solution, the immersion temperature is 60°C, and the immersion time is 5min.

2) Roughen the substrate, the formula of the roughening solution is: potassium permanganate 80g/L, sodium hydroxide 40g/L, immerse the substrate in the roughening solution, the immersion temperature is 70°C, and the immersion time is 3min.

3) Activate the substrate: prepare pyrrole solution concentration: volume ratio of pyrrole to ethanol is 1:3, ferric chloride solution: 2mol/L. First place the substrate in the pyrrole solution and let it stand for 10 minutes, then put the substrate in the ferric chloride solution and let it stand for 10 minutes. After 10 minutes, take out the substrate and place it on the boiling water vapor, steam fumigation for 2 hours, and then put Substrates were rinsed in deionized water.

4) After the third step of cleaning, the substrate is subjected to chemical copper precipitation treatment. In the chemical copper precipitation solution, the formula is potassium sodium tartrate 80g/L, sodium hydroxide 15g/L, sodium carbonate 7g/L; potassium sodium tartrate 8g/L, Copper sulfate pentahydrate 20g/L, nickel chloride 2g/L, formaldehyde 37% 30ml/L. The electroless copper deposition time is 4 hours, and a uniform red copper layer is obtained on the substrate, and the unit cell stacking on the substrate surface is more obvious.

Comparative example 1:

Compared with Example 1, most of them are the same, except that in this comparative example, the process of soaking in the pyrrole solution is omitted.

1) Carry out degreasing treatment to FR-4 glass fiber epoxy resin board, the formula of degreasing liquid is: sodium hydroxide 30g/L, sodium phosphate 50g/L, sodium carbonate 30g/L, OP-10 10ml/L, will The epoxy resin substrate is immersed in the degreasing solution, the immersion temperature is 60°C, and the immersion time is 5min.

2) Roughen the substrate. The formula of the roughening solution is: potassium permanganate 80g/L, sodium hydroxide 40g/L, and the epoxy resin substrate is immersed in the roughening solution. The immersion temperature is 70°C and the immersion time is 3min.

3) Activate the substrate: prepare ferric chloride solution: 1mol/L. Put the substrate in the ferric chloride solution, let it stand for 30 minutes, take out the substrate after 30 minutes, place the substrate above the boiling water vapor, fumigate with the steam for 30 minutes, and then transfer the substrate to deionized water to clean it.

4) After the third step of cleaning, the substrate is subjected to chemical copper precipitation treatment. In the chemical copper precipitation solution, the formula is potassium sodium tartrate 80g/L, sodium hydroxide 15g/L, sodium carbonate 7g/L; potassium sodium tartrate 8g/L, Copper sulfate pentahydrate 20g/L, nickel chloride 2g/L, formaldehyde 37% 30ml/L. The electroless copper deposition time is 4 hours, sporadic red spots appear on the surface of the substrate, and no uniform red copper layer is formed.

Comparative example 2:

Compared with Example 2, most of them are the same, except that in this comparative example, the process of steam fumigation is omitted.

1) Carry out degreasing treatment to FR-4 glass fiber epoxy resin board, the formula of degreasing liquid is: sodium hydroxide 30g/L, sodium phosphate 50g/L, sodium carbonate 30g/L, OP-10 10ml/L, will The epoxy resin substrate is immersed in the degreasing solution, the immersion temperature is 60°C, and the immersion time is 5min.

2) Roughen the substrate. The formula of the roughening solution is: potassium permanganate 80g/L, sodium hydroxide 40g/L, and the epoxy resin substrate is immersed in the roughening solution. The immersion temperature is 70°C and the immersion time is 3min.

3) Activate the substrate: prepare pyrrole solution: volume ratio of pyrrole to ethanol is 1:1, ferric chloride solution: 0.5mol/L. Put the substrate in the pyrrole solution, let it stand for 1 minute, then put the substrate in the ferric chloride solution, let it stand for 20 minutes, and after 20 minutes, turn the substrate into deionized water and clean it.

4) After the third step of cleaning, the substrate is subjected to chemical copper precipitation treatment. In the chemical copper precipitation solution, the formula is potassium sodium tartrate 80g/L, sodium hydroxide 15g/L, sodium carbonate 7g/L; potassium sodium tartrate 8g/L, Copper sulfate pentahydrate 20g/L, nickel chloride 2g/L, formaldehyde 37% 30ml/L. The electroless copper deposition time is 2h, and there is no uniform red copper layer on the surface of the substrate.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. A palladium-free activation chemical copper deposition process for a resin substrate is characterized by comprising the following steps:

(1) Sequentially carrying out oil removal treatment and roughening treatment on the resin substrate to obtain a pretreated resin substrate;

(2) Immersing the pretreated resin substrate into a pyrrole solution for a period of time, immersing the resin substrate into a ferric chloride solution, standing for a period of time to obtain a substrate with a polypyrrole film, placing the substrate with the polypyrrole film above boiling water to fumigate the substrate with the polypyrrole film by water vapor, and washing to obtain an activated substrate;

(3) And immersing the activated substrate into chemical copper deposition solution for chemical copper deposition to obtain the chemical copper plating layer.

2. The palladium-free activated electroless copper plating process for the resin substrate as claimed in claim 1, wherein in the step (2), the pyrrole solution is an ethanol solution of pyrrole, wherein the volume ratio of pyrrole to ethanol is 1 (1-3).

3. The palladium-free activated electroless copper plating process for resin substrate as claimed in claim 1, wherein in step (2), the soaking time in pyrrole solution is 1-10 minutes.

4. The palladium-free activated electroless copper plating process for resin substrate as claimed in claim 1, wherein in step (2), the concentration of ferric chloride solution is 0.5-2mol/L.

5. The palladium-free activated electroless copper plating process for resin substrate as claimed in claim 1, wherein in step (2), the standing time is 10-30 minutes.

6. The palladium-free activated chemical copper deposition process for a resin substrate as claimed in claim 1, wherein in the step (2), the fumigating time is 0.5-2h.

7. The palladium-free activation electroless copper plating process for the resin substrate as claimed in claim 1, wherein in the step (3), the electroless copper plating solution comprises 80g/L potassium sodium tartrate, 15g/L sodium hydroxide, 7g/L sodium carbonate, 8g/L potassium sodium tartrate, 20g/L copper sulfate pentahydrate, 2g/L nickel chloride and 37% of formaldehyde by weight of 30ml/L.

8. The palladium-free activated electroless copper plating process for the resin substrate as claimed in claim 1, wherein in the step (3), the electroless copper plating time is 1-4h.

9. The palladium-free activation electroless copper plating process for the resin substrate as claimed in claim 1, wherein in the step (1), the specific process of the degreasing treatment is as follows:

and (3) immersing the resin substrate into alkaline degreasing liquid for a period of time, and then washing to finish the degreasing treatment.

10. The palladium-free activated chemical copper deposition process for a resin substrate as claimed in claim 1, wherein the roughening treatment in step (1) comprises:

and (3) immersing the deoiled resin substrate into an acidic roughening solution, soaking for a period of time, and then washing to finish roughening treatment.

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