JPH1027950A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent shape change of a recognition mark by forming the recognition mark on a solder-coated printed wiring board and providing a resin layer at the center of the recognition mark. SOLUTION: For alignment between a part and a printed wiring board, recognition marks 13 are formed at two recognition-mark formation portions at diagonally opposite positions of the part. The recognition mark 13 is made of a copper layer at the same time of formation of a wiring pattern. When a solder resist 11 is formed on the surface of a printed wiring board 12 for protecting the surface of the printed wiring board 12, the solder resist 11 remains at about the center of the recognition mark 13, thus a resin layer 14 is formed. Alternatively, the resin layer 14 may be formed at the same time of component marking. When solder coating is performed on lands and the like where the part is packaged, attachment of the solder to the resin layer 14 is prevented. This prevents shape change of the recognition mark 13 at the next process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board on which components such as ICs are mounted using an automatic mounting machine.

[0002]

2. Description of the Related Art Generally, when components are mounted on a printed wiring board, automatic mounting is performed using a component mounting machine. In particular, when a large number of components are mounted on one printed wiring board or when components are mounted on a large number of printed wiring boards, automatic mounting is often used. When components are mounted on the printed wiring board, the lands formed on the printed wiring board are aligned with the leads of the components to be mounted, and the connection is made by soldering.

[0003] For example, QFP (Quad Flat P)
In the case of a surface mount component such as a package, the pitch between adjacent leads is, for example, about 0.25 mm. If the mounting position of the component is shifted even a little, the land and the component adjacent to the land to which the connection is originally made are connected. Mounting defects such as solder bridging between the leads and the like occur, and component connection cannot be performed accurately. Therefore, when mounting components on a printed wiring board, it is important to accurately position the components and the printed wiring board.

By the way, automatic mounting using a component mounter is performed in the following procedure. First, a recognition mark provided on a printed wiring board is read by a camera or the like on the component mounter to perform positioning, the positional relationship between the component mounter and the printed wiring board is determined, and fixed by means such as suction.
Then, the components to be mounted on the printed wiring board are mounted based on the component position information input to the component mounter. That is, the component is moved to a predetermined position on the printed wiring board by the arm of the mounting machine and placed. In the case of a component having a small lead pitch and requiring accurate positioning, such as the above-described QFP, a recognition mark provided in advance around a predetermined position of the component is read, and the accurate position of the component is determined. doing. In this way, the positioning is performed twice, such as first, the positioning of the component mounter and the printed wiring board, and then the positioning of the component and the printed wiring board.

[0005] Positioning is performed with reference to the recognition mark as described above. As the shape of the recognition mark, for example, shapes as shown in FIGS. 6A, 6B, and 6C are known. In this figure, 202 is a recognition mark, 20
1 is a solder resist, and 203 is an exposed base material. In addition, reading is performed by recognizing the difference between the recognition mark 202 and the optical reflectance around the recognition mark 202 with a camera. Therefore, the shape of the outer portion of the recognition mark 202 is very important. Further, it is necessary to provide the recognition mark at a position where accurate positioning can be performed without obstructing the wiring, and it is preferable to provide the recognition mark at two or more places as far away as possible.
In general, two recognition marks used to position the printed wiring board at a predetermined position of the component mounting machine are provided diagonally at the end of the printed wiring board. In general, two or more recognition marks used for positioning the component and the printed wiring board are provided on the diagonal of the component mounting position.

Usually, the recognition mark is formed by the same method at the same time as the wiring pattern. For example, when a wiring pattern is formed by etching, a recognition mark is also formed by etching when the wiring pattern is etched.

[0007]

However, regarding a substrate in which a conductor portion exposed from a solder resist of a printed wiring board has been subjected to a solder coating process (hereinafter, referred to as an SC process), the position is recognized in the above-described component mounting. Was not performed correctly. Here, the SC processing will be briefly described. On the surface of the printed wiring board,
Generally, a solder resist is applied for surface protection, but portions such as lands on which components are mounted are exposed from the solder resist. In this specification, for the purpose of preventing oxidation of the land portion and the like, and for enhancing the affinity between the land and the solder at the time of component mounting, etc., a solder coating process applied to a portion exposed from the solder resist is referred to as an SC process. Call. As a specific method of SC processing, for example, after applying a solder resist, immersing the printed wiring board in a bath filled with molten solder, pulling out of the bath and simultaneously blowing air, solder on the solder resist There is a method of removing.

Since the recognition mark is also optically recognized, it is exposed from the solder resist. When the SC processing is performed, the surface is coated with solder. As described above, position recognition is not performed accurately during component mounting.
When the inventors repeatedly examined the problem,
It has been found that this is based on the following reasons. That is, as shown in FIG.
When 1 is coated on the recognition mark 102 provided on the base material 103, the solder is thickly attached to the center of the recognition mark 102 due to the problem of the surface tension of the solder. The solder is formed with a thickness of 20 μm to 80 μm.

When the solder is thickly attached to the central part of the recognition mark, the solder may come into contact with the manufacturing apparatus in a later process, be pinched and held at the time of external processing, or be piled up for transportation, as shown in FIG. As shown in (1), the solder is crushed, and the recognized shape changes. Therefore, the shape of the recognition mark is not the originally intended shape, and correct recognition cannot be performed.

According to the present invention, even when the SC processing is performed, a change in the shape of the recognition mark is unlikely to occur in subsequent steps, so that erroneous recognition does not occur at the time of positioning, and therefore, components are mounted with high reliability. It is an object of the present invention to provide a printed wiring board capable of performing such a method, and to obtain such a printed wiring board without increasing the number of steps and the manufacturing cost.

[0011]

According to a first aspect of the present invention, a solder resist is applied to a surface on which a component is to be mounted, and the position of the component is recognized at the time of mounting the component. A printed wiring board having a recognition mark, on which a solder coating is applied, a resin layer is provided substantially at the center of the recognition mark. In such a means, it is necessary to perform a step of forming a resin layer.
There is a demand for a printed wiring board which does not cause an increase in the number of steps and an increase in manufacturing cost. The invention described in claim 2 has been made based on such a demand.

According to a second aspect of the present invention, in the printed wiring board according to the first aspect, the resin layer is made of a solder resist ink or a component marking ink.

In the present invention, unless otherwise specified, in order to determine the positional relationship between the component mounter and the printed wiring board, a recognition mark provided diagonally near the outer periphery of the printed wiring board, and a printed wiring board. In order to determine the positional relationship between the board and the component to be mounted, the recognition mark provided around the component mounting position on the printed wiring board is simply referred to as a recognition mark.

[0014]

According to the first aspect of the present invention, since the resin layer is provided substantially at the center of the recognition mark, the phenomenon that the solder adheres thickly to the center of the recognition mark is eliminated. The shape change of the recognition mark becomes very small.

According to the second aspect of the present invention, since the resin layer is made of a solder resist ink or a component marking ink, it is possible to form the resin layer simultaneously with the step of forming the solder resist or the component marking. Become.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, according to an embodiment of the present invention,
The present invention will be described in detail. As shown in FIG. 2, two recognition mark forming portions 17 at diagonal positions of the printed wiring board 15 are formed.
Next, a recognition mark for determining the position of the printed wiring board with respect to the component mounter is formed. A recognition mark used for alignment was formed. FIG. 3 is an enlarged view of the QFP component mounting portion A, and the recognition mark 13 is formed so that the component can be accurately mounted on the land 16 of the QFP. In FIG. 3, the solder resist is not shown. In FIG. 3, a resin layer 14 is formed at the center of the recognition mark 13. FIG. 1 shows the details of the recognition mark portion.
As No. 3, it was formed simultaneously with the wiring pattern. The thickness of the copper layer was 50 μm. The thickness of the copper layer is not particularly limited. 1
Reference numeral 1 denotes a solder resist, between which the base material 12 is exposed.

Then, at the time of forming the solder resist 11, the solder resist was left at about 1.0 mm square almost at the center of the copper layer to form a resin layer 14. The thickness of this resin layer was 20 μm. The resin layer may be formed at the same time when the other component marking is formed. As the forming means, after the entire surface is applied, exposure and development may be performed using a predetermined mask, or screen printing may be performed. As a material for the resin layer, a solder resist or an ink for component marking may be used.
Epoxy resin is often used, but other materials such as acrylic resin and polyimide resin can also be used.

The thickness of the resin layer is preferably about 15 μm to 25 μm. When formed simultaneously with the solder resist, the thickness becomes the same as the thickness of the solder resist, and when formed simultaneously with the component marking, the thickness becomes the same as the thickness of the component marking. And SC
FIG. 4 is a cross-sectional view of the recognition mark portion after the processing is performed.
A resin layer 14 is formed on the recognition mark 13, and a solder 19 is formed in a portion where no resin exists by the SC process. The solder is not repelled on the resin 14. Therefore, the phenomenon that the solder is thickly attached to the central portion of the recognition mark, which has been seen in the related art, is eliminated, and therefore, the shape change of the recognition mark in the subsequent process is very small. In the present invention, after the SC processing is performed, the recognition mark 1
The solder 19 formed on 3 is also called a recognition mark. This is because the part including the solder 19 is actually recognized by the component mounter.

Here, in the example of FIG. 1, the shape of the recognition mark 13 is a square, but the same effect can be obtained by forming a resin layer at the center of the shape, such as a circle or a triangle. Can be. Also, the shape of the resin layer 14 may be a shape such as a circle or a triangle, and is not limited to the same shape as the shape of the recognition mark. However, it is desirable that the resin layer and the recognition mark have the same shape in order to stabilize the solder and make it difficult for erroneous recognition to occur by making the portion where the solder adheres uniform.

As a result of forming such recognition marks, when component mounting is performed using a component mounter, the positional relationship between the component mounter and the printed wiring board, and the positional relationship between the printed wiring board and the mounted component. There was no misunderstanding when recognizing.

[0021]

According to the present invention, since the shape change of the recognition mark is very small, erroneous recognition does not occur at the time of positioning.
Therefore, it is possible to obtain a printed wiring board on which components can be mounted with high reliability. In addition, since the resin layer can be formed at the same time as the step of forming the solder resist or the component marking, the number of steps and the manufacturing cost do not increase.

[0022]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a recognition mark according to an embodiment of the present invention.

FIG. 2 is a diagram showing a position of a recognition mark of the present invention in a printed wiring board.

FIG. 3 is an enlarged explanatory view of a portion A in FIG. 2;

FIG. 4 is an explanatory sectional view of a recognition mark according to the embodiment of the present invention.

FIGS. 5A and 5B are cross-sectional explanatory views of a conventional recognition mark.

FIGS. 6A to 6C are explanatory diagrams of a conventional recognition mark.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Solder resist 12 Base material 13 Recognition mark 14 Resin layer 15 Printed wiring board 16 Land 17 Recognition mark formation part 18 Recognition mark formation part 19 Solder A QFP component mounting part

Claims (2)

[Claims] A printed wiring having a solder resist applied to a surface on which components are mounted, a recognition mark for performing position recognition at the time of component mounting, and a solder coating process applied on the recognition mark. A printed wiring board, wherein a resin layer is provided substantially at the center of the recognition mark. 2. The printed wiring board according to claim 1, wherein said resin layer is made of solder resist ink or component marking ink.