CN103037626A

CN103037626A - Circuit board surface treatment method by electroplating process

Info

Publication number: CN103037626A
Application number: CN2012101894498A
Authority: CN
Inventors: 黄明安
Original assignee: WUHAN KAIDISITE TECHNOLOGY Co Ltd; BEIJING KDS Co Ltd
Current assignee: WUHAN KAIDISITE TECHNOLOGY Co Ltd; BEIJING KDS Co Ltd
Priority date: 2012-06-11
Filing date: 2012-06-11
Publication date: 2013-04-10

Abstract

By adopting a circuit board surface treatment method by an electroplating process, needed metal is only needed to be plated on needed pads and needed keys, welded surface smoothness and high thickness requirements can be conveniently achieved, plating treatment of various metals can be easy to achieve, and the various metals include tin, nickel, gold, silver, palladium and the like. The procedures of surface treatment by the electroplating process includes circuit manufacturing, surface treatment by the electroplating process, resistance welding coating and follow-on production, and the aim to put the surface treatment by the electroplating process in front of the resistance welding coating is to electrically conduct the overall pads to be electroplated by copper metal.

Description

Galvanoplastic are carried out the method that PCB surface is processed

Technical field

The invention belongs to the technical field that PCB surface is processed, specifically adopt electric plating method that electroplating surface is carried out in the positions such as pad, button, through hole and process.

Background technology

The process for treating surface of wiring board mainly contains at present: hot air leveling, chemical nickel and gold, electric plating of whole board nickel gold, the heavy tin of chemistry, oxidation-resistant film coating etc.

Hot air leveling is the most frequently used process for treating surface, the surface irregularity after this method is processed, and tin thickness is not easy to realize the high planarization requirement of surface mount process effects on surface state between 1 ~ 20UM.

The surface smoothness of chemical nickel and gold and the heavy process of tin of chemistry is very good, but adopts the golden thickness of chemical deposition and tin thickness can not accomplish higher thickness, is not easy to realize high thickness requirement.

Electric plating of whole board nickel gold is wasted a lot of expensive metals on unwanted circuit, the welding resistance adhesive force of nickel gold face is also bad.

The evenness of oxidation-resistant film is better, but the ability of anti-multiple welding is relatively poor, the surface that can not have conductivity to require as button etc.

Adopt galvanoplastic to carry out the surface treatment of wiring board, only electroplate needed metal at pad, the button of needs, can realize easily face of weld planarization and higher thickness requirement, also be easy to realize the processing of various metals plating, comprise the metals such as tin, nickel gold, silver, palladium.

Summary of the invention

The method flow of currently used hot air leveling and chemical deposition is: the circuit manufacturing →Welding resistance applies →Surface treatment →Subsequent production, surface treatment procedure all are after welding resistance applies.

Galvanoplastic are carried out the surface-treated flow process: the circuit manufacturing →The galvanoplastic surface treatment →Welding resistance applies →Subsequent production, it is in order to allow the pad of electroplated all electrically conduct with the copper metal that the galvanoplastic surface treatment is placed on welding resistance coating purpose before.

Embodiment

Galvanoplastic surface-treated detailed process is:

Circuit is made →Electroless copper plating →Wet film replaces welding resistance to apply →Acid etching →The galvanoplastic surface treatment →Move back wet film →The alkalescence microetch →Welding resistance applies.

Electroless copper plating adopts common chemical copper technique, does not need to carry out de-smear and processes, and the purpose of electroless copper plating is that all pads are electrically conducted, and the thickness of chemical copper is 0.2 ~ 0.8um.

Wet film applies employing and applies the same method with welding resistance, and the purpose that wet film applies is that the surface coverage that does not need to electroplate is lived, and the thickness of wet film is 10 ~ 15um, does not carry out chemical cleaning and the processing of mechanical brush board before wet film applies.

The wet film exposure is adopted with the same film of welding resistance exposure and is exposed, if having welding resistance to cover, the network of electroplating then can not electrically conduct, so the used exposure film of wet film will check and revise in advance, guarantee that each network will connect copper, adopting the reason of wet film rather than dry film is that dry film is bad to the closely connected property of concavo-convex circuit.

The purpose of acid etching is to remove near the chemical copper of pad, and the microetch amount is 1 ~ 2um, only exposes pad locations, is beneficial to only pad be electroplated.

The galvanoplastic surface treatment is as negative electrode pad, plating metal is electroplated as anode, can electroplate various metals at pad, for example tin, nickel gold, silver, owing to be to adopt electric plating method, the purity of plated metal and thickness can be controlled very easily, can realize that very thick gold layer is to reach the requirement of the high reliability such as aviation.

Move back wet film and adopt normal caustic soda to carry out lift-off processing, when the metal active of plating is larger, can adopt isopropyl alcohol, acetone and other organic solvent to remove wet film.

The alkalescence microetch is in order to remove auxiliary chemical copper layer, and the metal level of electroplating is not produced corrosion, alkalescence microetch amount is 1 ~ 2um, the composition of alkalescence micro-corrosion liquid is ammoniacal liquor and hydrogen peroxide, the content of ammoniacal liquor in micro-corrosion liquid is the 13%(mass percent), the content of hydrogen peroxide is the 0.5%(mass percent), chemical equation is as follows:

Cu +4NH ₃ +H ₂O ₂--> [Cu(NH ₃) ₄](OH) ₂

Welding resistance can not adopt the method for machinery to carry out pre-treatment when applying, in order to avoid the metal of brushing power down plating, copper face is carried out alligatoring can be combined with alkaline microetch step, namely directly applies welding resistance after the alkaline microetch after washing oven dry.

The surface treatment of adopting above electro-plating method to carry out, relatively common surface treatment have mainly increased chemical copper on cost and wet film is made 2 steps, and overall Material Cost increase is greatly about 30 yuans/square metre.

If the effects on surface processing requirements is very high, adopt in the inaccessiable situation of commonsense method at the aspects such as evenness, hardness, purity, thickness and particulate metal of metal level, when perhaps the cost of method except institute's plating Material Cost of general chemistry deposition was higher than 30 yuans/square metre, adopting the present invention to carry out surface treatment was a very considerable method.

Claims

1. galvanoplastic surface-treated detailed process is:

2. the electroless copper plating in the claim 1 adopts common chemical copper technique, does not need to carry out de-smear and processes, and the purpose of electroless copper plating is that all pads are electrically conducted, and the thickness of chemical copper is 0.2 ~ 0.8um.

3. the wet film in the claim 1 applies employing and applies the same method with welding resistance, and the purpose that wet film applies is that the surface coverage that does not need to electroplate is lived, and the thickness of wet film is 10 ~ 15um, does not carry out chemical cleaning and the processing of mechanical brush board before wet film applies.

4. the wet film exposure is adopted with the same film of welding resistance exposure and is exposed, if having welding resistance to cover, the network of electroplating then can not electrically conduct, so the used exposure film of wet film will check and revise in advance, guarantee that each network will connect copper, adopting the reason of wet film rather than dry film is that dry film is bad to the closely connected property of concavo-convex circuit.

5. the purpose of the acid etching in the claim 1 is to remove near the chemical copper of pad, and the microetch amount is 1 ~ 2um, only exposes pad locations, is beneficial to only pad be electroplated.

6. the galvanoplastic surface treatment in the claim 1 is as negative electrode pad, plating metal is electroplated as anode, can electroplate various metals at pad, for example tin, nickel gold, silver, owing to be to adopt electric plating method, the purity of plated metal and thickness can be controlled very easily, can realize that very thick gold layer is to reach the requirement of the high reliability such as aviation.

7. the wet film that moves back in the claim 1 adopts normal caustic soda to carry out lift-off processing, when the metal active of plating is larger, can adopt isopropyl alcohol, acetone and other organic solvent to remove wet film.

8. the alkaline microetch in the claim 1 is in order to remove auxiliary chemical copper layer, and the metal level of electroplating is not produced corrosion, and alkaline microetch amount is 1 ~ 2um, and the composition of alkaline micro-corrosion liquid is ammoniacal liquor and hydrogen peroxide.

9. can not adopt the method for machinery to carry out pre-treatment when the welding resistance in the claim 1 applies, in order to avoid the metal of brushing power down plating, copper face is carried out alligatoring can be combined with alkaline microetch step, namely directly applies welding resistance after the alkaline microetch after washing oven dry.