WO2023273087A1

WO2023273087A1 - Solder mask stripping method and solder mask stripping chemical solution

Info

Publication number: WO2023273087A1
Application number: PCT/CN2021/129224
Authority: WO
Inventors: 张雪锋; 郭小青; 何德海; 曾攀
Original assignee: 智恩电子(大亚湾)有限公司
Priority date: 2021-06-30
Filing date: 2021-11-08
Publication date: 2023-01-05
Also published as: CN113194627A; CN113194627B

Abstract

The present application relates to a solder mask stripping method and a solder mask stripping chemical solution. The solder mask stripping method is performed according to the following steps: step 1, preparing a defective board; step 2, loading the defective board into an insertion frame; step 3, preparing a solder mask stripping chemical solution, and setting the temperature of the solder mask stripping chemical solution; step 4, putting the defective board and the insertion frame into a chemical solution tank, and continuously soaking for T1 time; step 5, putting the defective board and the insertion frame into a first water washing pool provided with an ultrasonic device, and performing water washing and soaking for T2 time; step 6, putting the defective board and the insertion frame into a second water washing pool, and performing water washing and soaking for T3 time; step 7, transferring the defective board into a first drying process, and performing strong hot air blow-drying; step 8, the defective board entering a second drying process, and performing hot air blow-drying; step 9, the defective board entering a cold air cooling process for cooling treatment; and step 10, collecting the board. According to the present application, re-washing time is shortened by 40 min, the efficiency is improved, a re-washing temperature is reduced, energy is saved, the quality is improved, and thoroughly soaking and washing are performed in a 0.2 mm of a via hole.

Description

Solder resist film removal method and solder resist film removal solution

technical field

The present application relates to the technical field of power circuits, in particular to a solder resist film removal method and a solder resist film removal solution.

Background technique

With the development trend of miniaturization and high density of electronic products, the aperture of the via hole is getting smaller and smaller, and the requirements for rework (ie rework) of solder mask stripping are getting higher and higher. When the PTH (PTH is the abbreviation of Plated Through Hole, plated through hole means metallized hole) via hole <0.2mm, it is easy to cause abnormalities such as ink plugging and poor backwashing.

[Corrected 22.02.2022 under Rule 91]
In the existing process flow: bad board→insert→soaking in liquid medicine tank (time 50-60min, temperature 80-90℃)→water washing soaking 1 (time 10min)→water washing soaking 2 (time 10min)→high pressure water gun rinsing→developing Punching (relative moving speed 1m/min) → plate collection (Note: The potion tank is equipped with two sets of ultrasonic devices). Existing liquid medicine formula is as accompanying drawing Fig. 2.

The ink on the surface of the board is removed through the compatibility principle of caustic soda and solidified ink, but the ink in the hole cannot enter due to the high aperture ratio and the large surface tension of caustic soda, so it can only be removed by high-pressure water washing and developing punching. Inner ink seriously affects product yield and production efficiency.

It can be seen that the existing caustic soda film removal process has the defects of low efficiency and poor quality, and cannot meet the requirements of the existing PCB film removal rework.

In order to overcome the above deficiencies, we have applied for a solder resist film removal method and a solder resist film removal solution.

application content

The purpose of this application is to solve the problems of low efficiency, poor quality, and inability to meet the existing PCB film-removal rework requirements in the existing caustic soda film-removing process. The specific solution is as follows:

A method for removing a solder resist film, carried out according to the following steps:

Step 1, prepare the bad board to be unfilmed;

Step 2, install the defective board into the socket;

Step 3, equip the solder resist film removal potion in the potion tank without an ultrasonic device, and set the temperature of the solder resist film removal potion;

Step 4, put the bad board and the socket into the liquid medicine tank, and soak for T1 time continuously;

Step 5, put the soaked bad boards and inserts into the first washing pool equipped with an ultrasonic device, wash and soak for T2 time;

Step 6, put the bad boards and inserts that have been soaked in the first water washing into the second washing pool, and wash and soak for T3 time;

Step 7, transfer the bad boards that have been washed and soaked in the second step to the first drying process, and dry them with strong hot air;

Step 8, the defective board enters the second drying process and is dried with hot air;

Step 9, the bad board enters the cold air cooling process for cooling treatment;

Step 10, collect the board after film removal.

The proportioning of the solder-resist film-removing potion is: 80% of tap water, 10% of caustic soda, 7% of leavening agent, and 3% of activator.

Further, the temperature of the solder mask stripping solution is 75-85°C.

Further, the continuous soaking T1 time in step 4 is: 20-30 minutes.

Further, the water washing and soaking T2 time in step 5 is 3-5 minutes.

Further, the temperature in the first washing tank is set at 27-28° C., and the number of the ultrasonic devices is two.

Further, the water washing and soaking T3 time in step 6 is 5 minutes.

Further, the temperature of the first drying process and the second drying process is set at 50-60°C.

Further, in the first drying process, the second drying process, and the cold air cooling process, the moving speed of the defective board on the assembly line is 5 m/min.

A solder resist film removal potion, which is used to prepare the solder resist film removal potion used in the above-mentioned solder resist film removal method, and is prepared according to the following ratio:

Tap water 80%

Caustic 10%

Leavening agent 7%

Activator 3%.

Further, the solid caustic soda, the liquid leavening agent and the activator in the solder resist film removal solution are mixed with water and fully stirred evenly, and the temperature of the solder resist film removal solution is set at 75-85°C.

In summary, adopting the technical solution of the present application has the following beneficial effects:

The application solves the problems that the existing caulking film removal process has low efficiency and poor quality, and cannot meet the requirements of the existing PCB film removal rework. In this application, the surface tension of caustic soda and leavening agent is reduced by activator, which is beneficial for the medicine liquid to enter the hole, and then the pore diameter of the ink molecules in the hole is loosened by the leavening agent, which has reached the post-development punching, and the hole can be removed at one time. The remarkable effect of the ink. This application has the following advantages:

1. The process flow is simplified;

2. Shorten the 40min backwashing time and improve efficiency;

3. Reduce the backwash temperature, save energy, reduce white spots on the substrate, and improve quality;

4. This application adjusts the position of the ultrasonic device, and the ink on the board is transferred from the liquid medicine tank to the water washing tank, which reduces the frequency of changing the liquid medicine tank (now the liquid medicine is changed once a month, and the liquid medicine needs to be changed once a week in the past), saving costs;

5. The inside of the 0.2mm via hole is soaked and cleaned, and there is no ink residue.

[Corrected under Rule 91 22.02.2022] Description of Drawings

[Corrected 22.02.2022 under Rule 91]
Fig. 1 is the test and the test data table of the formula of the solder resist and film removing solution of the present application;

[Corrected 22.02.2022 under Rule 91]
Fig. 2 is the existing potion formula table.

detailed description

The technical solutions in the embodiments of the present application will be clearly and completely described below. Apparently, the described embodiments are only some of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

Step 1, prepare the bad board to be unfilmed;

Step 2, install the defective board into the socket;

Step 3, equip the solder mask stripping potion in the potion tank without an ultrasonic device, and set the temperature of the solder resist stripping potion (the temperature of the solder resist stripping potion is 75-85°C.);

Step 4, put the bad board and the socket into the liquid medicine tank, and soak for T1 time continuously (T1 time: 20-30 minutes);

Step 5, put the soaked bad boards and inserts into the first washing tank equipped with an ultrasonic device, wash and soak for T2 time (T2 time is 3-5 minutes);

Step 6, put the bad boards and inserts that have been soaked in the first water washing into the second washing pool, and wash and soak for T3 time (T3 time is 5 minutes);

Step 7, transfer the defective board after the second water washing and soaking to the first drying process, and dry it with strong hot air; (this process is mainly to dry the moisture in the via holes)

Step 8, the bad board enters the second drying process and is dried with hot air; (this process is mainly for drying the water on the surface of the board)

Step 10, collect the board after film removal.

The proportion of the solder resist film removing potion is: 80% of tap water, 10% of caustic soda, 7% of leavening agent, and 3% of activator.

Further, the temperature in the first washing tank is set to 27-28° C., and the number of ultrasonic devices is two.

Furthermore, in the first drying process, the second drying process, and the cold air cooling process, the moving speed of the defective board on the assembly line is 5 m/min. The hair dryers in these three processes are respectively installed on the upper and lower sides of the bad board.

Tap water 80%

Caustic 10%

Leavening agent 7%

Activator 3%

Further, the solid caustic soda, the liquid leavening agent and the activator in the solder mask removing solution are mixed with water and then fully stirred evenly, and the temperature of the solder mask removing solution is set at 75-85°C.

As shown in the following "Experiment and Test Data Table of the Solder Resist Film Removal Potion Formula of the Application", the following combines the formulas of 5 groups of solder resist film removal potions, 4 groups of potion soaking times, 80 defective boards, and the temperature is 75 The specific tests at -85°C are analyzed as follows:

Group 1 is equipped with solder resist film removal potion according to the following ratio:

Tap water 80%, caustic soda 16%, leavening agent 3%, activator 1%

The test was carried out according to the soaking time of the liquid medicine for 10-20 minutes (minutes) and 20-30 minutes respectively, and the test results were: the inside of the hole was not clean, and the surface of the board was not clean. QA judged to be unqualified.

The test was carried out according to the soaking time of the potion for 30-40min and 40-50min respectively. The test results are: the hole is not cleaned cleanly, and the board surface is clean. QA judged to be unqualified.

Group 2 is equipped with solder resist film removal potion according to the following ratio:

Tap water 80%, caustic soda 13%, leavening agent 5%, activator 2%

The test was carried out according to the soaking time of the liquid medicine for 10-20min and 20-30min respectively. The test results were: some holes were not cleaned cleanly, and the board surface was not cleaned cleanly. QA judged to be unqualified.

The test was carried out according to the soaking time of the liquid medicine for 30-40 minutes and 40-50 minutes respectively. The test results are: some holes are not cleaned cleanly, and the surface of the board is clean. QA judged to be unqualified.

Group 3 is equipped with solder resist film removal potion according to the following ratio:

Tap water 80%, caustic soda 10%, leavening agent 7%, activator 3%

The test was carried out according to the soaking time of the liquid medicine for 10-20 minutes, and the test results were as follows: some holes were not cleaned cleanly, and the surface of the board was cleaned. QA judged to be unqualified.

The test is carried out according to the soaking time of the liquid medicine for 20-30 minutes or 30-40 minutes. The test result is: the inside of the hole and the surface of the board are cleaned. QA judges qualified. Considering the improvement of production efficiency and economic benefits, the best potion soaking time is selected as: 20-30min.

The test was carried out according to the soaking time of the potion for 40-50 minutes. The test results were: the inside of the hole and the surface of the board were cleaned, and the substrate was slightly whitish. QA judged to be unqualified.

Group 4 is equipped with solder resist film removal potion according to the following ratio:

Tap water 80%, caustic soda 7%, leavening agent 9%, activator 4%

The test was carried out according to the soaking time of the liquid medicine for 10-20min, 20-30min, 30-40min, and 40-50min respectively. The test results are: some holes are not cleaned cleanly, and the board surface is clean. QA judged to be unqualified.

Group 5 is equipped with solder resist film removal potion according to the following ratio:

Tap water 80%, caustic soda 4%, leavening agent 11%, activator 5%

The test was carried out according to the soaking time of the liquid medicine for 10-20min, 20-30min, 30-40min, and 40-50min respectively. The test results were: the inside of the hole was not clean, and the surface of the board was not clean. QA judged to be unqualified.

[Corrected 22.02.2022 under Rule 91]
The test and test data table of the formula of the solder resist and film removal potion of the present application are shown in Figure 1 of the accompanying drawings.

The application solves the problems that the existing caulking film removal process has low efficiency and poor quality, and cannot meet the requirements of the existing PCB film removal rework. In this application, the surface tension of caustic soda and leavening agent is reduced by activator, which is beneficial for the medicine liquid to enter the hole, and the intermolecular aperture of the ink in the hole is loosened by the leavening agent, which has reached the post-development punching, and the hole can be removed at one time. The remarkable effect of the ink. This application has the following advantages:

1. The process flow is simplified;

2. Shorten the 40min backwashing time and improve efficiency;

4. This application adjusts the position of the ultrasonic device, and the ink on the board is transferred from the liquid medicine tank to the water washing tank (that is, the first water washing tank), which reduces the frequency of changing the tank of the liquid medicine (now the liquid medicine is changed once a month, and the liquid medicine needs to be changed once a week. ),save costs;

The above description is the preferred implementation mode of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the application, some improvements and modifications can also be made, and these improvements and modifications are also considered For the scope of protection of this application.

Claims

A method for removing solder resist film, characterized in that, it is carried out according to the following steps:

Step 1, prepare the bad board to be unfilmed;

Step 2, install the defective board into the socket;

Step 3, equip the solder resist film removal potion in the potion tank without an ultrasonic device, and set the temperature of the solder resist film removal potion;

Step 4, put the bad board and the socket into the liquid medicine tank, and soak for T1 time continuously;

Step 5, put the soaked bad boards and inserts into the first washing pool equipped with an ultrasonic device, wash and soak for T2 time;

Step 6, put the bad boards and inserts that have been soaked in the first water washing into the second washing pool, and wash and soak for T3 time;

Step 7, transfer the bad boards that have been washed and soaked in the second step to the first drying process, and dry them with strong hot air;

Step 8, the defective board enters the second drying process and is dried with hot air;

Step 9, the bad board enters the cold air cooling process for cooling treatment;

Step 10, collecting the board that has been withdrawn from the film;

The proportioning of the solder-resist film-removing potion is: 80% of tap water, 10% of caustic soda, 7% of leavening agent, and 3% of activator;

The temperature of the solder resist film removing solution is 75-85°C, the continuous soaking T1 time in step 4 is 20-30 minutes, the water washing and soaking T2 time in step 5 is 3-5 minutes, and the first The temperature in the washing pool is set at 27-28°C, the number of the ultrasonic devices is two, the washing and soaking T3 time in step 6 is 5 minutes, the temperature of the first drying process and the second drying process Set at 50-60°C, the first drying process, the second drying process, and the cold air cooling process, the moving speed of the defective board on the assembly line is 5 m/min.
A solder-resist film-removing potion for preparing the solder-resist film-removing potion used in the solder-resist film-removing method described in claim 1, characterized in that it is prepared according to the following ratio:

Tap water 80%

Caustic 10%

Leavening agent 7%

Activator 3%.
According to claim 2, a solder resist film removing potion is characterized in that: the solid caustic soda, liquid leavening agent and activator in the solder resist film removing potion are fully stirred evenly after being mixed with water , The temperature of the solder mask stripping solution is set to 75-85°C.