JP2002198640A - Method for masking printed circuit board, and printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve inconvenience occurs when a method for printing and sticking masking ink on a printed circuit board having an opening part by a screen printing method. SOLUTION: In the method, a plurality of masking parts including the opening parts A to F of the printed circuit board 1 are masked. The opening parts are blocked by sticking a masking seal 2. Masking ink is printed/stuck to the printed circuit board in a state where it covers a plurality of masking parts including the masking seal blocking the opening part and the masking parts are connected by using a printing plate where an extraction pattern part corresponding to a plurality of masking parts including the masking seal blocking the opening parts and a connection pattern part connecting the extraction pattern parts are formed on the screen of a screen frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for masking a printed circuit board and a printed circuit board to which the masking method has been applied.

[0002]

2. Description of the Related Art During a manufacturing process of a printed circuit board, a portion to which a used chemical, ink or solder is not to be adhered is masked with a masking material such as an adhesive tape. The masking material is peeled off. Working steps using such a masking material include a flux applying step, a soldering step, a plating step, a contact carbon printing step, and the like.

For example, in a soldering process for simultaneously mounting a plurality of electronic components and the like on a printed circuit board by soldering, the electronic components are arranged on the printed circuit board and printed by a cream solder welding furnace or a solder dip device. Soldering is simultaneously performed at a predetermined position on the circuit board.

[0004] However, some electronic components cannot be soldered at the same time due to restrictions on heat resistance, shape, weight, and the like, and must be retrofitted. In addition, there are portions where it is not necessary to attach solder at the time of simultaneous soldering, such as a connector formed by applying gold plating to a part of a circuit wiring pattern, such as a contact portion of a mobile phone.

[0005] In such a case, the mounting maker is required to execute the operation shown in FIG.
As shown in (1), an adhesive tape for solder masking (masking material) is provided on a portion of the printed circuit board 101 corresponding to the electronic component (a solder land portion to which the electronic component is attached) or a portion where solder is not likely to adhere. 102 are attached to each other so that the solder does not adhere at the time of simultaneous soldering, and after other electronic components are simultaneously mounted by soldering, the adhesive tape 102 for solder masking is peeled off. Soldering to the land is performed.

When a masking material such as an adhesive tape is used at the time of the above-mentioned masking operation, the adhesive tape is cut into a predetermined shape with scissors or the like, adhered to a large number of places, and peeled off. The operation is complicated, requires a lot of man-hours, and is costly. In particular, it is labor intensive to perform the above-described operation each time on a large number of printed circuit boards. Adhesive tape needs to be adhered to many places, and accidents such as forgetting masking are likely to occur, resulting in poor yield. The adhesive tape is cut into a required shape with scissors or the like, but the shape accuracy is hardly obtained, and a masking error easily occurs. The adhesive of the adhesive tape remains on the printed circuit board, which requires labor to remove the adhesive tape, and in the case where the remaining wipe is generated, trouble occurs in subsequent operations. There were problems such as.

Therefore, the present inventors first applied a releasable masking ink on a printed circuit board by screen printing in a form of covering a plurality of masking portions and connecting the masking portions. (Patent No. 251496).

By using this method of attaching a masking material,
Since the masking can be performed at once by printing, the masking operation can be performed efficiently in a short time, and the masking of the masked portion can be prevented from being forgotten. In addition, since the cut pattern portion and the contact pattern portion formed on the screen can be designed in advance with required accuracy, masking can be performed with high accuracy, and masking errors can be prevented. Furthermore, since the masking material is attached in a shape connecting the masking portions, the masking material attached to a plurality of masking portions can be continuously peeled off by peeling off one portion, and the peeling operation can be efficiently performed. There were advantages.

[0009]

However, here,
The printed circuit board has screw holes for fixing, recesses for mounting components, relief holes for preventing contact, and other various holes and openings such as slits depending on the purpose of use of the printed circuit board. May be formed.

When the above-mentioned method of printing and applying the masking ink to the printed circuit board on which such openings are formed by screen printing is adopted, the masking ink to be printed in the openings drops, and the masking of the portions is masked. Inconveniences such as defects occurred and the ink portion dropped into the opening when the masking material was peeled off after the completion of the soldering operation or the like could not be removed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the above-mentioned disadvantages caused when a method of printing and applying a masking ink to a printed circuit board having the above-mentioned opening by a screen printing method. I do.

[0012]

According to the present invention, there is provided a method of masking a plurality of masking portions including an opening of a printed circuit board, the method comprising:
First, at least the opening is closed by affixing a masking seal, and then, on the screen of the screen frame, a punching pattern portion corresponding to a plurality of masking portions including a masking seal that closes the opening, and the punching pattern portion. Using a printing plate on which a connecting pattern portion to be connected is formed, masking ink is printed on a printed circuit board in a shape that covers a plurality of masking portions including a masking seal that covers the opening and that connects the masking portions. Masking method.

According to the method of masking a printed circuit board according to the present invention described above, first, at least the opening is closed by attaching a masking seal, so that the masking ink to be subsequently printed falls into the opening. However, inconveniences such as poor masking caused by the masking ink falling into the opening and tearing of the ink dropped into the opening caused at the time of peeling can be solved. Further, in the present invention, the masking ink is printed and adhered to the printed circuit board in a shape that covers a plurality of masking portions including the masking sticker previously attached and that connects the masking portions. In addition to preventing masking failure due to only the seal, at the time of peeling, it becomes possible to continuously peel off the masking material attached to a plurality of masking portions together with the masking seal.

Here, as the masking seal used in the present invention, a masking seal formed in advance with the same kind of ink as the above-mentioned masking ink is used, and as the masking ink, a liquid plasticizer is used. The use of a plastisol in which a thermoplastic resin powder is dispersed is advantageous for continuously removing the masking material attached to a plurality of masking portions formed by printing together with the masking seal, and as a masking material. It is preferable to show good properties.

Further, the printed circuit board which has been subjected to the masking method according to the present invention has no masking defect, and it is very easy to peel off the masking material after the work requiring masking is completed. Becomes

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described in detail below.

First, a masking seal is prepared by a screen printing method using a masking ink.

As the masking ink, a plastisol obtained by dispersing a thermoplastic resin powder in a liquid plasticizer can be used.

Here, the liquid plasticizer includes dimethyl phthalate, diethyl phthalate, dipropyl phthalate,
Dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, butyl benzene / phthalic acid, dioctyl phthalate, diisononyl phthalate, didedyl phthalate, diisodecyl phthalate, 2-ethylbenzyl phthalate, alkylbenzyl phthalate, dimethylcyclohexyl phthalate Phthalates such as triphenyl phosphate, tricresyl phosphate, tribenzyl phosphate, diphenyl decyl phosphate, and the like, and further, methyl (meth) acrylate, ethyl (meth) acrylate, Benzyl (meth)
Liquid low molecular weight polymer such as acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, triethylene glycol di (meth)
Acrylic (or methacrylic) such as acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate and tetra (meth) acrylate, polyester acrylate and methacrylate, polyurethane acrylate and methacrylate Oligomer, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, tributyl citrate, acetyl tributyl citrate and the like can be mentioned. To these, a photopolymerization initiator, a heat stabilizer, a curing accelerator and the like can be added as needed. Other liquid plasticizers include polyester,
Fats and oils such as soybean oil, and epoxy and urethane modified vegetable oils can be exemplified.

Examples of the thermoplastic resin powder include, for example, polyvinyl chloride and copolymers thereof, and polymers or copolymers of acrylic resins represented by polymethyl (meth) acrylate, which can be used in paste resins. Wax and the like can be mentioned, and these can be used alone or in a mixed form. If necessary, a coloring agent such as a pigment, a sol stabilizer, a thermal coloring inhibitor, a leveling agent, a thixo agent, and the like can be added. Examples of commercially available polyvinyl chloride include Zest P2 manufactured by Zeon Corporation.
1. Commercially available polymethyl (meth) acrylates include Zeon F301 and F30 manufactured by Zeon Corporation.
3, F303D, F303L, F340, and F351.

The above-mentioned liquid plasticizer and the above-mentioned thermoplastic resin powder are mixed and kneaded using a kneader, a planetary mixer, a Henschel or the like, so that a plastisol in which the above-mentioned thermoplastic resin powder is dispersed in the above-mentioned liquid plasticizer. After the preparation, the plastisol is degassed to obtain a masking ink.

As a method of forming a seal by a screen printing method using the above masking ink, first, a circular or rectangular shape is formed on a flat metal plate (particularly, preferably made of stainless steel) using a known screen printing machine. After forming a seal-shaped printed matter having a predetermined shape such as that described above, the seal-shaped printed matter is placed together with the metal plate in a heating or irradiation device, and is cured. As the heating or irradiating device, known infrared, far-infrared, and ultraviolet irradiating devices can be used, and any batch or conveyor-type heating or irradiating device can be used. Note that the heating temperature and the heating time or the irradiation temperature and the irradiation time are appropriately set depending on the type of the masking ink to be used, the thickness of the seal to be formed, and the like.

The thickness of the masking seal formed by the above method is 30 to 400 μm, preferably 10 to 400 μm.
It is desirable that the thickness be 0 to 250 μm. this is,
When the thickness of the seal is less than 30 μm, it is difficult to apply the seal to the printed circuit board. On the other hand, when the thickness of the seal exceeds 400 μm, it is difficult to print the masking ink described later. It is not preferable because it causes trouble. The thickness of the masking seal can be adjusted by adjusting the thickness of the screen of the screen printing plate, the thickness of the spacer interposed between the screen and the printing medium (metal plate), and the like.

For example, using a masking ink having the following composition, a circular sheet-like printed matter having a thickness of 150 μm and various diameters is formed on a stainless steel plate by a known screen printing machine. It was placed in a batch type infrared irradiation device and irradiated at 120 ° C. for 10 minutes. The obtained circular seal had a thickness of about 145 μm, was relatively flexible, and had some tackiness on the surface.・ Vinyl chloride acetic acid / vinyl copolymer 40.00% by weight ・ Diisononyl phthalate 56.50% by weight ・ SC-34 (stabilizer) 3.00% by weight ・ Phthalocyanine blue (colorant) 0.40% by weight ・Aerosil (powder silica) 0.10% by weight

Subsequently, the masking seal prepared as described above is attached to at least the opening of the printed circuit board to be masked.

For example, the printed circuit board 1 shown in FIG.
Has openings A, B, C, D, E, and F, and has solder lands a, b, c, d, e, and f. Of these, masking is performed. As shown in FIG. 2, the masking seals 2 were attached to the necessary openings C, D, E, and F, and the solder lands d requiring sufficient masking.

Subsequently, a printing plate on which a cut pattern portion corresponding to a plurality of masking portions including a masking seal for closing the opening and a connection pattern portion connecting the cut pattern portions is formed on the screen of the screen frame. A masking ink of the same type as the masking ink used to form the masking seal is used to cover a plurality of masking portions including a masking seal that covers the opening, and to connect the masking portions to each other to form a printed circuit board. After the printing, the masking ink is cured by placing it in a heating or irradiation device. As a heating or irradiation device for curing the masking ink,
The same ones used at the time of making the masking seal can be used.

The thickness of the coating film formed by the above masking ink formed on the printed circuit board by printing is 30
It is desirable to have a thickness of from 400 to 400 μm, preferably from 50 to 300 μm. If the thickness is less than 30 μm, there is a concern that the film may be broken at the time of peeling, and the properties (particularly, heat resistance) as a masking material are not good. In such a case, it is not preferable because it takes time to heat and cure.

For example, as shown in FIG. 3, a masking seal 2 for covering the openings D and E in FIG. 2 (since the masking of the openings C and F is necessary also in the next step, The seal 2 was avoided.), And the masking seal 2 attached to the solder land portion d requiring sufficient masking, and the punching pattern portions corresponding to the other solder land portions b, c, e, and f requiring masking. 1
1 and a masking ink having the following composition is printed and adhered on the printed circuit board 1 to a thickness of 150 μm on the printed circuit board 1 using the printing plate 10 in which the connection pattern portions 12 connecting the cut pattern portions 11 are formed on the screen 13. , Put the printed circuit board 1 into a batch type infrared irradiation device,
Irradiated at 0 ° C. for 20 minutes. Obtained printed circuit board 1
On the top, as shown in FIG. 4, a masking seal 2 for closing the openings D and E, a masking seal 2 attached to a solder land portion d requiring sufficient masking, and a plurality of other solder lands. The masking material 3 covering the portions b, c, e, and f and connecting them was formed with a thickness of about 145 μm. This printed circuit board 1
Is immersed in a solder bath (260 ° C.) for 20 seconds, taken out and cooled, and then, when the masking material 3 is peeled off from the end portion, the masking seal 2 for closing the previously attached openings D and E, and a sufficient The masking seal 2 covering the solder lands d requiring masking, and the masking material 3 covering the other plurality of solder lands b, c, e, and f were continuously peeled off at once. In addition, no adhesion of solder was observed at the portion masked by the masking material 3, and no adhesive remained on the printed circuit board 1 unlike the case where an adhesive tape was used. -Methyl methacrylate polymer powder 40.00% by weight (F303L manufactured by Zeon Corporation)-Methyl methacrylate low polymer (8 to 10-mer) 20.00% by weight-Acetyl tributyl citrate 36.50% by weight-SC -34 (stabilizer) 3.00% by weight ・ Phthalocyanine blue (colorant) 0.40% by weight ・ Aerosil (powder silica) 0.10% by weight

The characteristic feature of the present invention is that at least the opening to be masked existing on the printed circuit board is closed by attaching a masking seal, and then the masking seal and other masking parts are closed. The point is that the masking ink is printed and adhered in a shape that covers and connects these. Thereby, the masking ink to be printed does not fall into the opening, and masking defects caused by the masking ink falling into the opening, and inconveniences such as tearing of the ink portion falling into the opening caused at the time of peeling can be solved, A masking defect due to only the masking seal can be prevented, and at the time of peeling, the masking material adhered to a plurality of masking portions can be continuously peeled off together with the previously applied masking seal.

Also, if a masking seal is applied in advance to a portion (solder land portion d) requiring sufficient masking in addition to the opening, the masking effect at that portion by the masking ink to be printed and adhered thereafter. And the thickness of the coating film formed by the masking ink formed by printing adhesion can be designed to the minimum necessary coating film thickness in other parts.

Further, in the next step, if a masking seal attached to a portion (opening portions C and F) requiring masking is to be avoided and the subsequent masking ink is to be applied by printing, the masking of only that portion is required at the time of peeling. The seal remains, eliminating the need to mask that portion again prior to the next step.

In the case where a certain masking portion is distant from another masking portion and it is inconvenient to connect the masking portions with each other, a coating film using an independent masking ink is formed on these masking portions. Alternatively, it is needless to say that only the masking seal may be attached. As the masking seal, as described in the above embodiment, a masking ink that is formed in advance in a seal shape using the same type of ink as the masking ink to be printed and adhered is used. As shown in the embodiment, the use of a plastisol in which a thermoplastic resin powder is dispersed in a liquid plasticizer makes it possible to continuously apply a masking material adhered to a plurality of masking portions formed by printing together with a masking seal. While it is convenient for peeling off, it is preferable to show good properties as a masking material,
If the above-mentioned effects and effects of the present invention can be achieved,
The present invention is not limited to those shown in the above embodiments.

Although the preferred embodiments of the present invention have been described in various forms, the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention. Obviously you get it.

[0035]

According to the method for masking a printed circuit board according to the present invention as described above, the masking ink to be printed does not fall into the opening, but the masking defect caused by the masking ink falling into the opening is reduced. In addition, it is possible to eliminate inconveniences such as tearing of an ink portion that has fallen into an opening portion generated at the time of peeling, prevent a masking defect only by a masking seal, and at the time of peeling, a plurality of masking portions together with a masking seal applied earlier. This has the effect that the masking material adhering to the surface can be continuously peeled off. Further, the printed circuit board subjected to the masking method according to the present invention has a good yield because there is no masking defect, and it is very easy to peel off the masking material after the work requiring masking is completed. Therefore, there is an effect that the printed circuit board can be smoothly operated to the next process.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a printed circuit board on which a masking method according to the present invention is applied.

FIG. 2 is a plan view showing an example of a state in which a masking seal is attached to the printed circuit board of FIG.

FIG. 3 is a plan view showing an example of a screen printing plate used in the masking method according to the present invention.

4 is a plan view showing an example of a state in which a masking ink is printed and adhered to a printed circuit board to which a masking seal shown in FIG. 2 is attached by using a screen printing plate shown in FIG. 3;

FIG. 5 is a plan view showing an example of a state in which masking using a conventional adhesive tape is performed on a printed circuit board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Masking seal 3 Masking material formed by printing adhesion of masking ink 10 Printing plate 11 Die pattern part 12 Connection pattern part 13 Screen A, B, C, D, E, F Opening formed in printed circuit board Parts a, b, c, d, e, f Solder land parts formed on the printed circuit board

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akira Maeda 2-15-21 Yanagizaki, Kawaguchi-shi, Saitama Toyosei Printing Co., Ltd. F-term (reference) 2H084 BB02 BB12 CC10 CF03 CF06 2H113 AA01 AA04 BA10 BB07 BC10 CA17 DA53 DA56 DA68 FA03 5E314 AA26 AA47 BB07 BB11 CC07 CC15 DD01 DD06 GG24 5E319 AC01 BB05 CD29

Claims (4)

[Claims] In a method of masking a plurality of masking portions including an opening of a printed circuit board, first, at least the opening is closed by attaching a masking seal, and thereafter, the mask is sealed on a screen of a screen frame.
A masking seal that closes the opening with masking ink by using a printing plate on which a punching pattern portion corresponding to a plurality of masking portions including a masking seal that closes the opening and a connection pattern portion that connects the punching pattern portion are formed. A masking method for a printed circuit board, characterized by covering a plurality of masked parts including: and printing and attaching the masked parts to the printed circuit board in a shape connecting the masked parts. 2. The method for masking a printed circuit board according to claim 1, wherein the masking seal is formed in a seal shape in advance using the same kind of ink as the masking ink. 3. The method for masking a printed circuit board according to claim 1, wherein the masking ink is a plastisol having a thermoplastic resin powder dispersed in a liquid plasticizer. 4. A printed circuit board on which the masking method according to claim 1, 2 or 3 is applied.