JPH1051111A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate work by making an expensive jig unnecessary when a peel coat is formed on a through hole part, and improve peeling property when a peel coat is formed on a nonconductive penetrating hole part. SOLUTION: A conducting pattern 13 is formed on an insulating board 12, and a through hole 15 having a land 14 and a nonconductive penetrating hole 16 are formed. Almost the whole surface of the conducting pattern 13 except a connecting part and a contact part is covered with a solder resist 17. The inside except the land 14 and the shoulder part of the through hole 15, and the inside and the shoulder part of the penetrating hole 16 are also covered with the solder resist 17. A peel coat 18 for preventing the sticking of solder and flux in flow soldering is formed so as to cover the land 14 of the through hole 15 and spread a film in an aperture part of the penetrating hole 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printed wiring board having a through hole having a land or a non-conductive through hole formed in an insulating substrate.

[0002]

In an electronic circuit unit using a printed wiring board, as shown in FIG. 2, a conductor pattern 2 is formed on an insulating substrate 1 and a contact portion or a component on the surface thereof is connected. For example, after a component that can be automatically mounted is mounted in a temporarily fixed state on the printed wiring board 4 formed by covering the parts other than the solder resist 3 with a solder resist 3, flow soldering (soldering the soldering surface in a molten solder bath) ), And then the components are connected, and then the post-installed components are manually soldered and mounted, for example. The printed wiring board 4 is provided with a through hole 6 having a land 5, a non-conductive through hole 7, and the like.

However, in the flow soldering process, it is necessary to avoid the attachment of solder or flux to the contact portions and the connection portions of the retrofit parts.
For this purpose, although not shown, conventionally, before the flow soldering process (before the component mounting process), a heat-resistant masking tape is applied to the portion in advance to cover the portion, and after component mounting and flow soldering are performed. The masking tape had to be peeled off. However, the use of a heat-resistant masking tape as described above has a drawback such that the operation of attaching the tape becomes complicated.

Therefore, in recent years, as shown in FIG. 2, a peelable peel coat 8 has been formed on the surface of the printed wiring board 4 in place of the masking tape (for example, see Japanese Unexamined Patent Application Publication No. 61-69194). According to this, the coating of the peel coat 8 can be easily formed by printing or the like, and the operation can be simplified.

[0005] However, even when the above-described coating with the peel coat 8 is formed, when the above-mentioned through-holes 6 and the through-holes 7 are formed, the following problems are caused. That is, when forming the coating of the peel coat 8 on the through hole 6, the peel coat 8 is formed so that a film is formed on the surface of the opening of the through hole 6. If the diameter is large (for example, φ2.0 mm or more), the film may not be formed, and the material may enter deeply into the hole.

If the material of the peel coat 8 penetrates deeply into the hole of the through-hole 6 as described above, it may be difficult for the peel coat 8 to be peeled at the time of peeling and may remain in the hole. Conventionally, as shown in FIG. 2, a backup jig 9 is inserted into the through hole 6 from the opposite side, and a peel coat 8 is formed to prevent such a problem. However, this requires an expensive backup jig 9.

As for the through hole 7, if the hole has a relatively small diameter (for example, φ2.0 mm or less), a film is formed on the surface of the opening with a peel coat 8, but at the same time, as shown in FIG. As shown in (1), the material of the peel coat 8 enters into the through holes 7 to some extent. However, the material (for example, glass epoxy resin) of the insulating substrate 1 is exposed in the inside of the through hole 7 and the shoulder, and the surface of the material has fine irregularities. Is remarkably higher than other parts, and there is a problem that it is not easily peeled off at the time of peeling, but remains torn. For this reason, the through-hole 7 is not covered by the peel coat 8 but is coated by using a conventional masking tape, and the drawback of complicating the work has not been solved.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to use an expensive jig when forming a peel coat for preventing adhesion of solder or flux in a through-hole portion. An object of the present invention is to provide a printed wiring board which is unnecessary and can facilitate the operation. A second object of the present invention is to provide a printed wiring board capable of improving peelability when a peel coat for preventing adhesion of solder or flux is formed in a non-conductive through-hole portion. is there.

[0009]

According to a first aspect of the present invention, there is provided a printed wiring board having a conductor pattern formed on an insulating substrate and a through hole having a land used in an exposed state. The invention is characterized in that the inside and the shoulder of the through hole are covered with a solder resist (the invention of claim 1).

[0010] According to this, since the inside and the shoulder of the through hole are covered with the solder resist, no solder or flux adheres even if flow soldering is performed. Therefore, it is not necessary to form a peel coat for preventing solder and flux from adhering in the flow soldering so that a film is formed on the surface of the opening of the through hole. In addition, since the inside and the shoulder of the through hole do not directly become a contact portion or a connection portion, there is no problem even if the through hole is covered with a non-peelable solder resist.

At this time, a structure in which a peelable peel coat is coated on a portion of the land of the through hole which is not covered with the solder resist can be adopted (the invention of claim 2). According to this, a peelable peel coat can be easily formed on the land, which is a portion of the through hole where solder and flux adhesion prevention measures are required, and the peel coat is also easily peeled. .

Further, a second printed wiring board according to the present invention comprises:
A conductive pattern is formed on an insulating substrate and a non-conductive through hole is formed in the insulating substrate. The inside and the shoulder of the through hole are covered with a solder resist. 3 invention). According to this, the inside and the shoulder of the through hole are covered with the solder resist, and the material of the insulating substrate is not exposed. At this time, since the surface of the solder resist has high smoothness, even if a peel coat is formed, the adhesive strength is small.

Therefore, if a peel coat capable of being peeled off is formed so as to cover the opening portion of the through hole (the invention of claim 4), adhesion of solder or flux in the flow soldering process can be prevented. , And the peel coat can be easily peeled off.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention (corresponding to claims 1 to 4) will be described below with reference to FIG. FIG. 1 shows a configuration of a main part of a printed wiring board 11 according to the present embodiment. Here, a predetermined hole processing (through holes and through holes described later) is performed on the insulating substrate 12 made of, for example, a glass epoxy copper clad laminate, and copper plating is performed on both the front and back surfaces and inside the holes (through holes). The predetermined conductor pattern 13 is formed on both front and back surfaces by etching.

At the same time, a through hole 15 having a land 14 is formed on the left side in the figure, and a non-conductive through hole 16 is formed on the right side in the figure. In this case, the diameter of the through hole 15 is relatively large (for example, φ
The diameter of the through hole 16 is relatively small (for example, φ2.0 mm or less). Incidentally, the land 14 of the through hole 15 is ultimately used as, for example, a contact portion, and the through hole 16 is finally used as, for example, a connector attaching portion.

On the front and back surfaces of the printed wiring board 11, almost the entire surface of the conductor pattern 13 except for connection parts such as components and contact points is covered with a solder resist 17 made of, for example, an epoxy-based synthetic resin. In this embodiment, the inside and the shoulder of the through hole 15 are also covered with the solder resist 17 except for the land 14, and the inside and the shoulder of the through hole 16 are also covered with the solder resist 17. You. The solder resist 17 is formed by applying a spray coating method or the like and then removing unnecessary portions by a photographic method. Also,
Normally, the solder resist 17 is in a state where it cannot be peeled off.

Further, a surface (upper surface in FIG. 1) of the printed wiring board 11 on which soldering is performed in a subsequent flow soldering step is provided with a peel coat for preventing adhesion of solder and flux in the flow soldering. 18 is coated. In the present embodiment, the peel coat 18 is provided so as to cover the upper surface of the solder resist 17, and covers the land 14 of the through hole 15 (portion not covered by the solder resist 17). The film is formed so as to stretch over the 16 opening portions.

The peel coat 18 is formed, for example, by applying a resist ink by a screen printing method or the like and then curing the applied ink by heating or the like. Unlike the solder resist 17, the peel coat 18 can be easily peeled off, and is finally peeled off the printed wiring board 11.

Next, the operation of the above configuration will be described. In manufacturing an electronic circuit unit using the printed wiring board 11 having the above-described configuration, for example, components that can be automatically mounted are temporarily mounted on the printed circuit board 11, and then flow soldering (soldering to a molten solder bath) is performed. The components are connected by performing a soldering method of immersing the surface), and then the post-installed components are manually mounted by soldering, for example. The peel coat 18 is peeled off from the printed wiring board 11 after the flow soldering process.

However, in the flow soldering process, it is necessary to avoid the attachment of solder or flux to the contact portions (lands 14) and the connecting portions of the retrofit parts. However, in this embodiment, the through holes 15
Since the upper surface of the land 14 is covered with the peel coat 18, the solder or the flux does not adhere to it. In addition, it is needless to say that the solder must not adhere to the conductive portion inside the through hole 15. However, since the inside and the shoulder of the through hole 15 are covered with the solder resist 17, the flow soldering is performed. However, no solder adheres.

In this case, even though the diameter of the through-hole 6 is large in the past, it was necessary to provide the peel coat 8 so as to extend the film to prevent the adhesion of the solder or the like to the inside of the through-hole 6. On the other hand, in the present embodiment, the peel coat 18 for preventing the adhesion of solder and flux is provided with the through hole 1.
Since there is no need to form a film on the surface of the opening 5, an expensive backup jig 9 conventionally required
Is unnecessary, and can be performed at low cost.

The peel coat 18 is formed in the through hole 1.
5 does not get inside, so the peel coat 18
The peeling of the peel coat 18 can be easily performed, and the peel coat 18 does not break off and remain in the through hole 15. Since the inside and the shoulder of the through hole 15 do not directly serve as contact portions or connection portions, there is no problem even if the through hole 15 is covered with the non-peelable solder resist 17.

Since the peel coat 18 is formed on the through hole 16 so as to form a film on the opening, solder and flux adhere to the through hole 16 in the flow soldering process. Can be prevented. At this time, as shown in the figure, the peel coat 18 is formed so as to partially enter the inside of the through hole 16,
Since the inside and the shoulder of the through hole 16 are covered with the solder resist 17, the material of the insulating substrate 12 is not exposed in the inside and the shoulder of the through hole 16.

For this reason, the solder resist 1 having high smoothness
The peel coat 18 will be formed on the surface of No. 7,
As compared with the case where the peel coat 18 is directly adhered to the material of the insulating substrate 12, the adhesive force of the peel coat 18 is significantly reduced. Therefore, the peeling force at the time of peeling the peel coat 18 is small, and the peeling can be easily performed.
There is no danger of being left inside.

As described above, according to the present embodiment, the inside and the shoulder of the through hole 15 are coated with the solder resist 17,
Since the peel coat is formed on the land 14, an expensive jig is not required when the peel coat 18 is formed on the through hole 15, and the work can be facilitated. And the non-conductive through-hole 1
6 is coated with the solder resist 17 on the inside and the shoulder, and the peel coat 18 is formed so as to cover the opening of the through hole 16. Thus, the operation can be greatly simplified as compared with the case where the coating is performed using a conventional masking tape.

[0026]

As apparent from the above description, according to the printed wiring board of the present invention, an expensive jig is required when a peel coat for preventing the adhesion of solder or flux is formed in a through-hole portion. Is unnecessary, and the work can be facilitated. Also, in the case where a peel coat for preventing adhesion of solder or flux is formed in a non-conductive through-hole portion, the peelability can be improved. It has excellent practical effects.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a partial longitudinal sectional view of a printed wiring board.

FIG. 2 is a diagram corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

In the drawing, 11 is a printed wiring board, 12 is an insulating substrate, 13
Is a conductor pattern, 14 is a land, 15 is a through hole,
Reference numeral 16 denotes a through hole, 17 denotes a solder resist, and 18 denotes a peel coat.

Claims (4)

[Claims] 1. A method in which a conductor pattern is formed on an insulating substrate and a through hole having a land used in an exposed state is formed, and a solder resist is coated on an inside and a shoulder of the through hole. A printed wiring board characterized by the following. 2. The printed wiring board according to claim 1, wherein a portion of the land of the through-hole which is not covered with the solder resist is formed with a peelable peel coat. 3. An insulating substrate in which a conductor pattern is formed and a non-conductive through hole is formed, wherein the inside and the shoulder of the through hole are coated with a solder resist. Printed wiring board. 4. The printed wiring board according to claim 3, wherein a peel coat that can be peeled off is formed so as to cover the opening of the through hole.