JPS6338295A - Method of peeling-off protective film for soldering of printed wiring board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for forming a protective film on a printed wiring board, which can reduce the labor involved in soldering the printed wiring board. .

(Prior Art) When manufacturing a mounted printed wiring board by soldering mounted components to a printed wiring board, it is necessary to protect connectors and surface mounting parts from soldering.

Masking tape is usually used as this surface protection means. Masking tape is made of paper impregnated with heat-resistant resin and coated with a binder on the back side.
This is pasted on the parts where half the soldering is not desired, and the soldering is removed manually after the work is completed.

Therefore, when using this type of method, the masking tape must be applied manually to the predetermined position of the printed wiring board, which is not only troublesome but also costly. Not only does it have problems that cannot be automated, but it also requires time and effort to remove it manually, making it impossible to fully automate the process with soldering. It is the cause.

In addition, the binder used in masking tape hardens after soldering, and even when the masking tape is removed, some remains on the wiring board side, causing poor contact.To solve this problem, masking tape After peeling off, it is necessary to thoroughly clean the wiring board surface etc. with a solvent such as Triclean, but this makes the soldering process more laborious and there is a risk of damaging the wiring board surface itself.

(Purpose) In view of these points, the present invention allows the protective film formed on the parts not to be soldered to be easily peeled off, does not damage the surface of the printed wiring board itself, and makes soldering a work process. The purpose is to provide a protective film stripping method for soldering printed wiring boards that can be fully automated.

(Structure) In order to achieve the above-mentioned object, the present invention uses a resin having heat resistance higher than the temperature required for soldering and water solubility as a component in the soldering process of electronic components of printed wiring boards, etc. Apply ink to the parts of the printed circuit board surface that you do not want to solder to form a protective film, and after soldering electronic components, etc., spray a liquid containing alcohol as a main component onto the protective film. This method is characterized in that the protective film is melted and peeled off by spraying high-temperature water into contact with the protective film of the mounted printed wiring board.

(Example) The present invention will be described in detail below based on examples.

In the present invention, the steps for semi-IF application until drying the protective film are as follows.

That is, before mounting electronic components, electronic devices, etc. on a printed wiring board manufactured by etching or plating, the parts on the surface of the wiring board where soldering is not desired, such as a part of a connector or a surface mounting part, are A protective film is applied using ink made of a special resin. This ink has water-soluble and heat-resistant resin as its main component, and in this example, P, V, A, L, (Poly vinyl
l alcohol commonly known as p, v.

8, hereinafter simply referred to as P, V, 8), is melted in an amount of 60 to 70% by weight based on 100 parts of water.

The solid content dissolution test data of P, V, 8 are shown below.

[Test method] Powder (7) P, V, A, 60 g, 100 g of water at 70°C
After applying it to a glass plate, heat it at 50°C.
Dry thoroughly in an atmosphere of

A 1 cm2 piece of the solidified resin was cut out, placed in water set at each temperature, and the average time until it was sufficiently dispersed was visually measured.

[Test results] 20@C 10 minutes: Not dissolved 30@C 5 minutes: 40@C 2 minutes: 50°0 1 minute: 60@C 40 seconds Near 08C 25 seconds: Dissolved instantly at 80°C The above results are 20 degrees at each temperature. This is the average value using the number of samples. According to this result, it can be seen that the ink converted into Ill-1 is easily dissolved by water at a temperature of 30°C or higher.The mixing ratio of 4°P, V, A, and water is determined separately. Although not limited to this, when considering the viscosity of the ink and the viscosity of the ink +'1, a ratio of 1- is appropriate.

This ink is applied as a protective film (it may be applied by brushing, stamping, etc.) or the mounted printed wiring board is coated with a large 1. In the case of +; For 100, p
, v,^, within the range of 40 to 60% is sufficient for ili.

After applying 4 liters of ink for the protective film, it is dried.

The drying method may, of course, be dependent on natural bone drying, but if you try the following method, you can dry the short poem 1j1biC 1■,
Figure 54-1-., 7λ) "C-Kill" to save labor.

Immediately after forming ink 7ii 1-'-(-ho 11i 1II2), apply this protective film 4 niethyl alcohol and R
Sprinkle the liquid mixed with water from Step 1 into a mist.
Blow high-temperature air after 0 degrees C. When ethyl alcohol evaporates, it helps evaporate water in the ink, reducing drying time. Sprinkle with ethyl alcohol 11
If high temperature air is blown without heating, the water in the protective film may boil and the protective film itself may be damaged. Note that only ethyl alcohol may be sprayed before blowing hot air.

Next, lead wires or ends of electronic components, electronic devices, etc. are connected to the round ends of the printed wiring board by soldering by a desired method as in the conventional manner.

1- The results of the heat resistance test of the protective film using a hot ink are as follows.

[Test method] 60 g of powdered P, V, 8, 70'C (7) water 10
Diffuse it in 0g and apply it to the plating connector part11i.
to form a film of about 30 to 100 microns, and heated at 50°C.
Dry for 1.0 minutes under an atmosphere of To this coating! t'
= IJI trowel-melted clay (280°C) (1 tank 240°C) was applied and the situation was observed.

[Test Results] All of the 40 samples did not impair coating performance.

'1':1. I] (-1 After completing the work, protection 11Q
Peel off as follows.

As mentioned in 1, even if the ink that forms the protective film dries and becomes solid, it is water-soluble and can be easily dissolved and peeled off if immersed in water at a temperature of 30 degrees Celsius or higher. .

However, in order to perform this peeling work efficiently, it is necessary to spray ethyl alcohol on the dry protective film in the form of a mist, wait for a while (approximately 1 degree), and then
Mechanical vibrations similar to ultrasonic vibrations in the water containing warm water after cruising between ℃ and 70℃! It is best to do this while thinking. this is,
By first spraying ethyl alcohol, the hydrophilicity of ethyl alcohol to the protective film allows the peeling action in water to take place in a shorter time, and the ultrasonic vibrations allow the protective film to be removed over a relatively large area. This is because it will peel off easily.

Is it better to use ethyl alcohol mixed with water, or of course you can use it alone. Further, the liquid sprayed onto the protective film is not limited to ethyl alcohol as long as it is an alcohol with a volatility of 41-. Alternatively, the protective film may be brought into contact with the hot water by spraying hot water onto the protective film at a constant water pressure to peel off the protective film from the surface of the printed wiring board.

The mounted printed wiring board from which the protective film has been peeled off is removed from the peeler, sprayed with ethyl alcohol, and then forced dry by blowing hot air onto it.

Incidentally, if a coloring agent is added to the ink for forming the protective film described in 1 to color it, the protective film portion can be visually recognized and the work becomes easier.

Furthermore, the ink used in the present invention has a temperature lower than the temperature required for the purpose. Other resins can be used as long as they can withstand the temperatures of 1 and 2 and are water-soluble.

(Effects) As described above, according to the present invention, when soldering electronic components to a printed wiring board, an ink containing a resin that is water-soluble and has a certain degree of heat resistance is used to solder the electronic components. A protective film is formed by applying it to the parts that do not want to be soldered, and after the soldering process is completed, a liquid mainly composed of alcohol is sprayed on the protective film in the form of a mist, and then high-temperature water is applied to the mounted printed wiring board. Since the protective film is melted and peeled off by contacting the protective film, only the protective film can be easily peeled off without damaging the surface of the printed wiring board.

In addition, this peeling method uses hot water to melt and peel off the protective film, so it can be automated without manual intervention, and the soldering process can be fully automated. Become.

Furthermore, since the protective film forming ink that has been melted and peeled off can be recovered using a special filter, it is possible to reduce the cost of soldering work by reusing it.

Patent applicant: Vixes International Co., Ltd.

Claims (5)

[Claims] (1) In the soldering process of printed wiring boards, an ink containing a resin that is water-soluble and has heat resistance higher than the temperature required for soldering is applied to the parts of the printed circuit board surface where soldering is not desired. After forming a protective film and completing the soldering work of electronic components, etc., spray a mist of liquid containing alcohol as a main component onto the protective film, and bring high-temperature water into contact with the protective film of the mounted printed wiring board. A method for removing a soldering protective film for a printed wiring board, characterized by melting and peeling off the protective film. (2) The liquid sprayed in the form of a mist is a liquid obtained by mixing ethyl alcohol with a small amount of water. Method. (3) A method for peeling a soldering protective film of a printed wiring board, wherein the high temperature water is hot water of about 50°C to 70°C. (4) The contact with high-temperature water is performed by jetting high-temperature water of about 50 to 70 degrees Celsius onto the printed wiring board after soldering at a constant water pressure. The method for removing a soldering protective film from a printed wiring board according to item 1. (5) The above-mentioned contact with high-temperature water is performed by immersing the printed wiring board after soldering in a bath containing high-temperature water of around 50°C to 70°C, and oscillating ultrasonic waves toward the printed wiring board. A method for removing a soldering protective film on a printed wiring board, characterized in that the method is performed by: