JPH11145607A - Method of forming soldered resist film on printed circuit board and printed circuit board manufactured there by - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent solder bridges from being generated between lands adjacent to each other in the direction of flow soldering, by a method wherein a film using a solder resist is formed on a printed circuit board in such a way that each opening, which is larger than the diameter of an electronic component insertion hole formed in each land and has a size that the peripheral edges of each land are covered, is formed on each land. SOLUTION: A multiple of conductor patterns 2 are arranged on the soldering surface of a printed circuit board 1 adjacent to each other in a row form at a narrow pitch along the direction of flow soldering, each land 3 is formed on the respective conductor patterns 2 and an insertion hole 3a for mounting an electronic component is made to open in each land 3. A no-through hole is formed in each hole 3a, and an opening 5a larger than that in each land 3 and somewhat smaller in size than that of the outer edges of each land 3 is formed on a film using a solder resist 5 formed on the respective surfaces of the lands 3. As a result, when the electronic components are automatically sldered to the board 1, solder bridges are never generated between the lands adjacent to each other in the direction of the flow soldering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board having a land with an insertion hole for an electronic component, and particularly to a solder bridge between lands adjacent in the flow direction when the electronic component is subjected to flow soldering. Regarding things that did not occur.

[0002]

2. Description of the Related Art In the past, the work of attaching electronic components to a printed circuit board relied on manual labor.
It's already common sense to do it by machine, especially if it's increasingly mechanized, especially if it's mass-produced. The work of inserting and mounting electronic components on the land uses an automatic insertion machine,
Thereafter, flow soldering is performed by an automatic soldering device.

[0003] In particular, recently, an integrated mass production line in which an automatic insertion machine and an automatic soldering apparatus are connected by one conveyor has been frequently used.

[0004]

However, since the land on which the insertion hole for the electronic component is formed is a thin land formed on the surface of the insulating substrate by copper foil or electroless plating, the land is soldered to the insertion hole. When an external force is applied to a lead or the like of an electronic component mounted thereon, the lead easily peels off. Therefore, in order to make it difficult to peel, large lands are formed to increase the bonding strength with the insulating substrate, but between adjacent lands, the lands are formed vertically long to reduce the pitch. ing.

However, even when the lands are vertically elongated and the pitch is narrowed, especially when a plurality of lands are formed adjacent to each other on a printed circuit board, the flow direction is reduced when the electronic components are flow soldered. There is a problem that a solder bridge is likely to be generated between lands adjacent to each other. FIGS. 5 and 6 are views showing an example of the solder bridge.

FIG. 5 shows that a plurality of lands 103 are formed adjacent to the solder surface of a printed circuit board 101, and the substrate 10 is inserted into an insertion hole 103a formed in each land 103.
1, the lead 104a of the electronic component 104 is inserted from the surface and flow soldered from the solder surface.
A solder bridge 108 is formed between the adjacent lands 103A and 103B.

FIG. 6 shows a vertical cross-sectional structure of a main part of a printed circuit board upside down. In these figures, 102 is a conductor pattern formed on the solder surface of the printed circuit board 101, and 105 is a conductor pattern 102
Is a solder resist coated so that the solder 106 does not adhere to the substrate, and 107 denotes an insulating substrate. The present invention provides a printed circuit board that does not cause a solder bridge as described above.When a printed circuit board on which a land having an insertion hole for an electronic component is formed is flow-soldered with an electronic component, It is an object of the present invention to provide a method for preventing a solder bridge from forming between lands adjacent in a direction and a printed circuit board manufactured by using the method.

[0008]

According to one aspect of the present invention, a method of manufacturing a printed circuit board includes the steps of:
When forming a coating with a solder resist on a printed circuit board having a land with an insertion hole for an electronic component,
A printed circuit, wherein a coating with a solder resist is formed on the land so as to form an opening having a size larger than the electronic component insertion hole and having a size that covers the periphery of the land. A method for forming a solder insulating film on a substrate is proposed.

According to a second aspect of the present invention, there is provided a printed circuit board, wherein a land having an opening for inserting an electronic component is formed,
On a printed circuit board in which a solder resist coating is formed on the solder surface of the circuit board, an opening is formed in the land that is larger than the electronic component insertion hole of the land and has a size enough to cover the periphery of the land. It is characterized by being coated with a solder resist.

[0010] Claim 3 also proposes a printed circuit board. In this printed circuit board, the electronic component insertion hole is a no-through hole for projecting the lead of the electronic component to the solder surface of the circuit board. The present invention is characterized in that a flow soldering is performed by passing a board through a solder bath or applying a solder jet from a solder surface of the circuit board.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The method for forming a solder insulating film according to the present invention includes the steps of: etching a copper-clad surface of a single-sided copper-clad laminate; forming a conductor pattern; In addition, when forming a coating with a solder resist, the size of an opening that is not covered with the solder resist is adjusted for each land where the electronic component insertion hole is opened.

Here, there are two types of methods for coating the solder resist, a screen printing type and a photo solder resist type, and any of these methods may be used. FIG. 1 shows an example in which a plurality of lands having electronic component insertion holes are arranged in a row at a relatively narrow pitch along the direction of solder flow, and between these lands, a land is formed. The solder resist film is formed over the solder surface of the circuit board so that an opening having a size larger than the formed electronic component insertion hole and slightly smaller than the outer edge of the land is formed.

According to the present invention, in forming the solder resist film in the process of manufacturing the printed circuit board, the size of the opening formed in the solder surface of the electronic component insertion hole is adjusted. The opening of the solder resist can be adjusted by using, for example, a mask pattern. Next, an embodiment of a printed circuit board manufactured by the method of the present invention will be described.

FIGS. 1 and 2 show an embodiment of a printed circuit board according to the present invention proposed in claim 2. As shown in these figures, the printed circuit board 1 has a large number of conductor patterns 2 arranged in a row at a narrow pitch along the solder flow direction on the solder surface of the printed circuit board 1. Lands 3 are formed in the respective conductor patterns 2, and the lands 3 are provided with insertion holes 3 a for mounting electronic components. Also, a portion (not shown) for mounting electronic components is provided on the solder surface of the printed circuit board 1.
Except for the above, a coating of the solder resist 5 is formed on the solder surface.

Here, the insertion holes 3a formed in the lands 3 form no through holes, and the coating of the solder resist 5 formed on the solder surface of each land 3 is formed in the land 3. An opening 5a having a size larger than the insertion hole 3a and slightly smaller than the outer edge of the land 3 is formed. FIG. 3 shows a state in which the electronic component 4 is mounted on the printed circuit board of the present invention. In the printed circuit board 1, the lead 4a of the electronic component 4 is inserted into a no through hole formed as the insertion hole 3a. Flow soldering is performed through a solder bath or a solder jet.

FIG. 4 shows another example of the solder insulating film formed on the solder surface of the land where the insertion hole of the electronic component is formed. In this figure, an opening 5a 'formed in a land 3 in which an insertion hole 3a of an electronic component is formed, which is formed adjacently in a row at a narrow pitch, has a small side along the solder flow direction, On the side orthogonal to the solder flow direction, it is widely formed. By reducing the amount of solder attached on the side along the solder flow direction and increasing the amount of solder attached on the side perpendicular to the solder flow direction, solder bridges can be prevented and the leads of electronic components can be inserted at the same time. This prevents a decrease in solder bonding strength when the semiconductor device is inserted and mounted in 3a.

In the embodiment described above, an example is shown in which the present invention is applied to a printed circuit board 1 formed by a subtractive method. However, the present invention is applicable to a case in which a land 3 is formed by electroless plating by an additive method. Can also be applied. Further, the present invention can be applied to a case where the insertion hole 3a of the electronic component is not a through hole as in the embodiment but a through hole.

[0018]

As can be understood from the above description, according to the method for forming a solder insulating film of a printed circuit board according to the first aspect, since the size of the opening of the solder resist is adjusted, an additional step is required. Since it can be formed of a conventional printed circuit board material without any change, the manufacturing cost is low.

According to the printed circuit board of the second aspect,
Since the solder insulating film is provided so as to form an opening having a size larger than the electronic component insertion hole of the land and covering the periphery of the land, even if the land is formed in a vertically long shape, When soldering electronic components automatically, no solder bridge is formed. Claim 3
According to the printed circuit board described in (1), the bonding strength between the land and the insulating substrate can be maintained even when a no-through hole having a large land size is used as the electronic component insertion hole.

[Brief description of the drawings]

FIG. 1 is a partial plan view on the solder side showing an example of a printed circuit board of the present invention.

FIG. 2 is a vertical cross-sectional view of a main part showing an example of a printed circuit board of the present invention.

FIG. 3 is a main part longitudinal sectional view showing a state where electronic components are mounted on the printed circuit board of the present invention.

FIG. 4 is a partial plan view on the solder side showing another example of the printed circuit board of the present invention.

FIG. 5 is a partial plan view on the solder side showing an example of a conventional printed circuit board.

FIG. 6 is a vertical cross-sectional structural view of a main part showing an example of a conventional printed circuit board.

[Explanation of symbols]

 Reference Signs List 1 printed circuit board 3 land 3a insertion hole 4 electronic component 4a lead 5 solder resist 5a opening

Claims (3)

[Claims] When a solder resist film is formed on a printed circuit board having a land with an insertion hole for an electronic component, the land is larger than the electronic component insertion hole, and A method for forming a solder insulating film on a printed circuit board, comprising forming a coating with a solder resist so as to form an opening having a size enough to cover the periphery. 2. A printed circuit board in which a coating made of solder resist is formed on a solder surface of a circuit board on which a land having an opening for inserting an electronic component is formed, wherein the land has a larger height than the electronic component inserting hole of the land. A printed circuit board having a structure in which a coating with a solder resist is formed so as to form an opening having a size large enough to cover the periphery of the land. 3. The electronic component insertion hole according to claim 2, wherein the electronic component insertion hole is a no-through hole for projecting a lead of the electronic component from a solder surface of the circuit board. A printed circuit board with a structure that performs flow soldering by applying a solder jet from the solder surface.