CN112492776B

CN112492776B - Method for selective plating of inner blind holes of ultrathin plate

Info

Publication number: CN112492776B
Application number: CN202011517414.3A
Authority: CN
Inventors: 王康兵; 周刚; 唐文锋
Original assignee: HUIZHOU DAYA BAY MILLION SOURCES PCB CO LTD
Current assignee: HUIZHOU DAYA BAY MILLION SOURCES PCB CO LTD
Priority date: 2020-12-21
Filing date: 2020-12-21
Publication date: 2021-05-25
Anticipated expiration: 2040-12-21
Also published as: CN112492776A

Abstract

The invention discloses a selective plating method for inner blind holes of an ultrathin plate, which is completed according to the following steps: film pressing: carrying out DuPont pressure plating resistant dry film on the build-up plate; exposure: taking the blind hole point and the area for bearing the blind hole point as selective plating areas, taking the rest areas as non-plating areas, enlarging the whole selective plating area by 0.2mm to obtain a negative film, and exposing the non-plating areas; and (3) developing: developing a selective plating area; copper deposition: depositing a layer of thin copper on the wall of the blind hole by a chemical method, wherein a dry film in a selective plating area is not damaged and falls off in a copper deposition process; electroplating: electroplating is carried out on the selective plating area, the electroplating condition is 10ASF 51MIN, the thickness of electroplated copper is 7-8 mu m, and the problems of size deformation and enlargement of blind hole depression values of the boards are solved by setting the blind hole selective plating process, so that the product yield is ensured, the quality leakage risk is reduced, the rework rate is greatly reduced, the process capability is effectively improved, the production efficiency is improved, and the core competitiveness of the production process is improved.

Description

Method for selective plating of inner blind holes of ultrathin plate

Technical Field

The invention belongs to the technical field of PCB manufacturing, and particularly relates to a method for selectively plating inner blind holes of an ultrathin plate.

Background

In the prior art, the flow design of a common inner-layer blind hole is laser drilling, copper deposition and hole filling electroplating, the design is not suitable for a stacked blind hole product with ultra-thin copper thickness, and because the inner-layer copper thickness is thinner, a board subjected to hole filling electroplating according to the conventional process requirement needs acid etching to meet the copper thickness requirement.

The production difficulties brought by the conventional method are as follows:

1. the etched copper-reduced plate can meet the roughness of the copper surface only by brushing, but the thin plate cannot be brushed and easily generates dimensional deformation;

2. blind holes are subjected to hole filling and electroplating, and the recess values are also enlarged after copper is reduced by etching aiming at dense areas of the blind holes, so that the blind holes are overlapped abnormally;

the difficulty directly and greatly reduces the production efficiency of products, and simultaneously, the rework rate is high, the quality loss risk is increased, and the processing capacity is greatly weakened.

Disclosure of Invention

The embodiment of the application provides a method for selectively plating blind holes in an inner layer of an ultrathin plate, and the problems of size deformation and large blind hole sunken value are solved by setting a blind hole selective plating process, so that the product yield is ensured, the quality leakage risk is reduced, the rework rate is greatly reduced, the processing capacity is effectively improved, the production efficiency is improved, and the core competitiveness of the production process is improved.

The technical scheme provided by the embodiment of the application is as follows:

a method for selectively plating blind holes in an inner layer of an ultrathin plate is completed according to the following steps:

a. film pressing: carrying out DuPont pressure plating resistant dry film on the build-up plate;

b. exposure: taking the blind hole point and the area for bearing the blind hole point as selective plating areas, taking the rest areas as non-plating areas, making a negative film by using engineering data obtained after the selective plating area is enlarged by 0.2mm for compensation, placing the negative film under the irradiation of an ultraviolet lamp for polymerization and crosslinking reaction, and exposing the non-plating areas;

c. and (3) developing: developing a selective plating area;

d. copper deposition: removing glue residue in the hole, changing the surface tension in the hole, depositing a layer of thin copper on the wall of the blind hole by a chemical method, and enabling a dry film in a selective plating area to be free of damage and fall off in a copper deposition process;

e. electroplating: electroplating the selective plating area under the condition of 10ASF 51MIN, wherein the thickness of the electroplated copper is 7-8 μm.

Further, the ultra-thin plate has a thickness ratio of less than 0.003 mm/layer.

According to the invention, the blind hole selective plating process is set, the flow is optimized, the steps are adopted to complete the selective plating of the blind holes of the ultrathin plate, the product quality of the ultrathin plate is effectively ensured, the size of the ultrathin plate and the concavity of the blind holes are both in a normal range, the processing capacity is effectively improved, the production efficiency is improved, and the core competitiveness of the production process is improved.

Furthermore, the thickness of the safety glue pressed at one time after the selective plating is more than 8 μm.

Furthermore, the thickness of the safety glue pressed twice or more after the selective plating is 4-8 μm.

Wherein, the safety glue is thick and is the vertical distance from the copper surface to the glass fiber cloth. Through setting up safe thick glue, can be after the pressfitting, the electro-coppering in the blind hole can not show out, and the radium-shine layer of accepting of effective guarantee blind hole is not punctured, improves the quality reliability.

Furthermore, the alignment target is shot in the blind hole selective plating process by adopting an X-RAY target-watching and target-shooting mode, and through the arrangement, the alignment accuracy is effectively guaranteed, and the product quality is guaranteed.

The invention has the beneficial effects that:

through setting up the blind hole selective plating technology, solved the problem that board size deformation, blind hole depressed value are drawn big to guarantee the product yield, reduce the quality and leak out the risk, greatly reduced rework rate effectively promotes the processing procedure ability, promotes production efficiency, improves production technology core competitiveness.

Drawings

FIG. 1 is a schematic diagram of the selective plating process for ultra-thin blind holes of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Examples

To facilitate an understanding of the present invention for those skilled in the art, the present invention will be described in further detail below with reference to specific embodiments and accompanying drawings.

c. and (3) developing: developing a selective plating area;

Wherein, the safety glue is thick and is the vertical distance from the copper surface to the glass fiber cloth. Through setting up safe thick glue, can be after the pressfitting, the electroplating copper post in the blind hole can not show out, and the radium-shine layer of accepting of effective guarantee blind hole is not punctured, improves the quality reliability.

The invention has the beneficial effects that:

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art. It should be noted that the technical features not described in detail in the present invention can be implemented by any prior art.

Claims

1. A method for selectively plating blind holes in an inner layer of an ultrathin plate is characterized in that the thick layer ratio of the ultrathin plate is less than 0.003mm per layer, and the method is completed according to the following steps:

film pressing: carrying out DuPont pressure plating resistant dry film on the build-up plate;

exposure: taking the blind hole point and the area for bearing the blind hole point as selective plating areas, taking the rest areas as non-plating areas, making a negative film by using engineering data obtained after the selective plating area is enlarged by 0.2mm for compensation, placing the negative film under the irradiation of an ultraviolet lamp for polymerization and crosslinking reaction, and exposing the non-plating areas;

and (3) developing: developing a selective plating area;

copper deposition: removing glue residue in the hole, changing the surface tension in the hole, depositing a layer of thin copper on the wall of the blind hole by a chemical method, and enabling a dry film in a selective plating area to be free of damage and fall off in a copper deposition process;

electroplating: electroplating the selective plating area under the condition of 10ASF 51MIN, wherein the thickness of the electroplated copper is 7-8 μm.

2. The method of claim 1, wherein the thickness of the safety paste for one pressing after the selective plating is greater than 8 μm, wherein the safety paste is the vertical distance from the copper surface to the glass fiber cloth.

3. The method for selective plating of blind holes in an inner layer of an ultrathin plate as claimed in claim 1, wherein the thickness of the safety glue with the pressing times of more than or equal to two times after selective plating is 4 μm to 8 μm, wherein the thickness of the safety glue is the vertical distance from the copper surface to the glass fiber cloth.

4. The method of claim 1, wherein an X-RAY target-looking and targeting manner is used to shoot alignment targets during blind hole selective plating.