JPH08307022A - Printed board - Google Patents

Abstract

PURPOSE: To provide a printed board wherein solder may attach to the surface of a pattern in the uniform thickness by surface tension from backward in the movement direction of the printed board when the printed board is so moved that a swollen section of the surface of the melted solder may be cut off for reducing a conductor resistance of the wiring pattern. CONSTITUTION: On the surfaces of wiring patterns 1a-1d, resist lines 1e which have components vertical to the movement direction of a printed board 1 are formed with resist material. Such resist lines 1e are made by forming the resist in a pattern of stripes, lattice, or polka dots.

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 wiring pattern through which a large current flows, such as a power supply circuit.

[0002]

2. Description of the Related Art A conventional printed board is shown in FIG. In the figure, 1a, 1b, 1c and 1d represent wiring patterns, respectively, which are obtained by dissolving and removing a copper foil attached to a printed circuit board with an acidic solution so that the pattern as shown remains. Is.

[0003]

When a large current is to be passed through the printed board, it is necessary to widen the pattern width of the printed board to lower the conductor resistance. However, when downsizing the equipment, the area of the board itself is reduced. May be limited and a sufficient pattern width may not be secured. In such a case, the conductor resistance has been conventionally reduced by attaching solder to the entire pattern through which a large current flows.

To attach solder to the entire pattern,
Conventionally, a flow soldering device has been used. The flow soldering device is a solder bath in which a part of a flat liquid surface is raised by generating an upward jet in the melt and a printed board in which the flat surface of the solder melt is parallel to the surface. And a transport mechanism that moves the solder melt so as to cut off the rising portion of the solder melt, and as the printed board moves, the pattern surface is covered with the solder melt at almost the same speed as the moving speed of the printed board. Since the soldering by the flow soldering device is usually performed in the state where the circuit components are mounted on the printed board, the rising height of the solder melt is precisely controlled.

When the printed board 1 is moved in the direction of arrow A when soldering is performed using this flow soldering apparatus,
Solder attached to the patterns 1a to 1d is printed board 1
As a result, the surface tension of the solder pulls it in the direction of the arrow B, and the amount of solder in the vicinity of the C portion decreases, so that there is a problem that the expected conductor resistance cannot be obtained and the pattern heats up.

An object of the present invention is to provide a printed board on which solder can be uniformly attached to a pattern surface without changing the structure or operating method of the flow soldering apparatus.

[0007]

In order to solve the above problems, according to the present invention, as described in claim 1, a line having a component perpendicular to the moving direction of the printed board is resisted on the surface of the wiring pattern. It is formed using a material. Then, as described in claim 2, it is extremely preferable to form the resist line into a straight line having the full pattern width.

Further, a plurality of resist lines having the full pattern width are formed, and a plurality of linear resist lines are formed on the surface of the wiring pattern in the same direction as the moving direction of the printed board. Then, it is more preferable if the surface of the wiring pattern is divided into a plurality of sections by the resist lines. Alternatively, as described in claim 4, the resist line having a component in a direction perpendicular to the moving direction of the printed board may be a circular line.

In this case, as described in claim 5,
It is preferable that a plurality of circular resist lines are formed so as to form circular regions independent of each other.

[0010]

According to the present invention, when a line having a component in a direction perpendicular to the moving direction of the printed board is formed on the surface of the wiring pattern by using a resist material, from the rear side of the resist line in the moving direction of the printed board. Even if the surface tension acts, the resist line acts as a weir to prevent the solder from moving.Therefore, the solder having the thickness of the resist line remains in front of the resist line, and the solder in the entire wiring pattern remains. The thickness of the wiring becomes thicker and the degree of reduction in the conductor resistance of the wiring pattern becomes smaller.

Further, within the width of the resist line itself, the thickness of the conductive layer becomes thinner than the width of the width by the height of the resist line, so that the current density in the width increases and the temperature rises when energized. However, since the conductive layers on both sides of the wire are thick, the temperature rise is small, the temperature in the width is transmitted to both sides, the temperature in the width decreases to near the temperature on both sides, and the soldered wiring pattern is energized. The effect of the presence of resist lines on capacitance can be substantially ignored.

Therefore, when the resist line is formed on the surface of the wiring pattern, if the resist line is formed to the full width of the pattern, the solder drawn out from the outside of the line end of the resist line disappears, and the resist line is formed. The front side solder thickness is not reduced. In addition, when the resist line is formed in a straight line, a negative type resist (a photosensitive material having a characteristic of being polymerized or cross-linked by irradiation of light or electron beam to be insoluble or hardly soluble in a developing solution and left on the pattern surface after development) ) Makes it easy to draw a line on the resist applied on the surface of the wiring pattern.

Therefore, when a plurality of linear resist lines having the full pattern width are formed as described in claim 3,
The thickness of the solder between the two resist lines shows a thickness distribution that becomes thinner from the rear side to the front side due to the surface tension received from the rear side of the resist line until the solder hardens.
By reducing the distance between the lines of the book, the thickness of the front side becomes smaller, the thickness of the solder layer becomes thicker on the entire pattern surface, and the conductive resistance can be effectively reduced. Further, by forming a plurality of linear resist lines in the same direction as the moving direction of the printed board and dividing the pattern surface into a plurality of sections by the resist lines, the circuit board mounting state of the printed board and the printed board carrying mechanism are When the moving direction of the printed board is changed due to the relationship or the like, the solder layer can be kept thick as the entire pattern surface even if the printed board is slightly tilted or shakes.

When the resist wire is a circular wire as described in claim 4, the thickness of the solder layer in the circle and the solder layer on the front side of the circle is thicker than in the case where the resist wire is not formed. Therefore, the conductor resistance of the pattern can be lowered. Therefore, if a plurality of circular resist lines are formed so as to form mutually independent circular areas as described in claim 5, the pattern surface is changed even when the moving direction of the printed board is changed, as in the case of claim 3. The thickness of the entire solder layer can be made thick and uniform.

[0015]

FIG. 1 shows the first embodiment of the present invention. In the figure, 1 is a printed board, 2 is a switch, 3 is a connection line,
Soldering is performed on the patterns 1a to 1d. Reference numeral 1e is a resist line in which a straight line having a desired height is formed by using a resist material, and a plurality of resist lines are formed at right angles to the moving direction of the printed board 1 shown by arrow A, at the full width of the pattern, and at intervals. Has been done.

When the printed board 1 whose pattern surface is divided by the resist lines 1e as shown in the figure is moved so as to cut off the raised portion on the surface of the solder melt, solder in each section is transferred from the rear side in the moving direction of the printed board 1. Even if the surface tension acts, each resist wire 1e acts as a dam to prevent the movement of the solder in the section, so that the soldering is performed to the thickness of the resist wire in each section. Specifically, in each section, the thickness of the solder on the front side is slightly thinner than that on the rear side due to the influence of the surface tension. However, since the width of each section is narrow, the difference in thickness is small, and the height of the resist line 1e in the entire pattern is high. It is possible to form a solder layer having a thickness approximately equal to the thickness. In addition, the width of the resist line itself is formed to be narrow within a range in which the required mechanical strength can be obtained under the temperature of the solder melt.

FIG. 2 shows a second embodiment of the present invention. This embodiment shows a printed board in which a plurality of linear resist lines in the moving direction of the printed board are formed in addition to the resist lines in the first embodiment shown in FIG. By dividing the pattern surface into a plurality of sections by a plurality of linear resist lines in the two directions at right angles, the solder in each section may be pulled by the surface tension from the rear side in the moving direction of the printed board 1. Even if the printed board 1 slightly tilts or shakes during the movement, the solder in each section passes over the resist line due to the solder movement preventing action as a weir of the resist line 1e and the surface tension of the solder itself in each section. Therefore, it becomes difficult to enter the adjacent section, and it becomes easy and sure to maintain the solder thickness of the entire pattern at the height of the resist line.

FIG. 3 shows a third embodiment of the present invention. This embodiment shows a printed board in which the resist line having a component in a direction perpendicular to the moving direction of the printed board is a circular resist line 1e. The circular resist line 1e is formed so that the centers of three adjacent circles are located at the vertices of an equilateral triangle so as to form a closed curve, that is, circles of the same diameter can be arranged most densely. It is formed distributed on the surface. By forming the resist lines in this way, not only the solder inside the circle but also the solder outside the circle has no relation to the moving direction of the printed board, and even if there is a slight tilt or shake of the printed board during movement. It becomes difficult for the solder to move on the entire surface of the pattern, and a solder layer having the same thickness as the height of the resist line can be formed on the entire surface of the pattern.

[0019]

According to the present invention, a printed board which is moved so as to cut off the raised portion on the surface of the solder melt for forming a solder layer on the surface of the wiring pattern for reducing the conductor resistance of the wiring pattern Since the line having the component in the direction perpendicular to the moving direction is formed using the resist material on the surface, the solder coated on the wiring pattern is pulled by the surface tension from the rear side in the moving direction of the printed board. However, since the resist line having a height acts as a weir to prevent the solder from moving on the front side of the resist line, the thickness of the solder increases on the entire pattern surface, and the conductor resistance is effectively reduced. It is possible to hold the printed board small and increase the current carrying capacity of the pattern without increasing the width.

In the printed board according to the second aspect, since the resist line according to the first aspect is a straight line having the full pattern width,
2. There is no portion of the solder on the front side of the resist line in the printed board moving direction that is pulled backward by the surface tension.
You can maximize the effect of. Further, since the resist line is a straight line, by using a negative type resist as the resist material, it becomes easy to draw a line on the resist applied on the surface of the wiring pattern.

In the printed board according to the third aspect, since the plurality of resist lines according to the second aspect are formed, the gap between the two resist lines is appropriately set and the solder thickness between the two resist lines is not varied. The uniformity can be reduced, and the thickness of the solder can be increased on the entire pattern surface. Also,
A plurality of resist lines according to claim 2 and a plurality of linear resist lines at right angles to the resist lines are formed to divide the pattern surface into a plurality of sections. Therefore, the direction of movement of the printed board is changed and the printed board is slightly inclined. Even if there is a sway, the solder layer can be kept thick as the entire pattern surface.

In the printed board of claim 4, since the resist line is formed in a circular shape, it is difficult to move the solder inside the circle and the front side solder in the circular printed board moving direction, and the same effect as in claim 2 is obtained. To be In the printed board according to the fifth aspect, the same effect as that of the third aspect can be obtained without dividing the entire surface of the pattern, depending on the diameter and arrangement of the circular resist lines formed.

[Brief description of drawings]

1A and 1B show a first embodiment of a printed board according to the present invention, in which FIG. 1A is a side view and FIG. 1B is a top view.

FIG. 2 shows a second embodiment of the printed board according to the present invention, (a) is a side view and (b) is a top view.

FIG. 3 shows a third embodiment of the printed board according to the present invention, (a) is a side view and (b) is a top view.

FIG. 4 shows a surface state of a wiring pattern in a conventional printed board, (a) is a side view of the printed board,
(B) Top view

[Explanation of symbols]

 1 printed board 1a wiring pattern 1b wiring pattern 1c wiring pattern 1d wiring pattern 1e resist line

Claims (5)

[Claims] 1. A flat liquid surface is parallel to a flat liquid surface of a solder melt in which a part of a flat liquid surface is raised by generating a jet in the liquid and the like. In a printed board in which the thickness of a wiring pattern is increased by moving the wiring pattern in a cutting manner, the wiring pattern is formed on the surface using a resist material with a line having a component in a direction perpendicular to the moving direction. A printed board characterized by. 2. The printed board according to claim 1, wherein the resist line having a component in a direction perpendicular to the moving direction of the printed board is a straight line having a full pattern width. 3. The linear resist line according to claim 2, wherein a plurality of linear resist lines in a direction perpendicular to the moving direction of the printed board are formed and a straight line in the same direction as the moving direction of the printed board is formed on the surface of the wiring pattern. A printed board, wherein a plurality of resist lines are formed, and the surface of the wiring pattern is divided into a plurality of sections by the resist lines. 4. The printed board according to claim 1, wherein the resist line having a component in a direction perpendicular to the moving direction of the printed board is a circular line. 5. The printed board according to claim 4, wherein a plurality of circular resist lines are formed so as to form circular areas independent of each other.