JPH0234988A - Printed board and manufacture thereof - Google Patents

Abstract

PURPOSE:To suppress flow-down of solder into a through hole by forming a solder land partly on a whole periphery on the upper face of the hole, and soldering a conductor thereon. CONSTITUTION:A solder land 37 formed on a conductive foil 11 on the periphery of the upper face of a through hole 13 is formed merely on the part of a side extended at the intermediate 24 of a conductive conductor 21. Thus, a resist film 15 formed on the foil 11 is formed on other surface except the land 37, and a resist film 15 is formed on the part of the side opposite to the side extended at the intermediate 24 of the conductor 21. A solder 36 adheres to the land 37, and the foil 11 is connected to the intermediate 24 of the conductor. Thus, when the land 37 formed on the part of the whole periphery of the hole is soldered by placing the conductor thereon, the solder melted through the hole 13 or the conductor inserted into the hole is prevented from flowing out.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a novel structure of a printed circuit board forming an electric circuit and a method of manufacturing the same. More specifically, it relates to an optimal structure and manufacturing method for use when connecting circuits on the front and back sides of a printed circuit board via conductors.

Conventional technology Fig. 3 is a sectional view of a conventional printed circuit board, and Fig. 4 is a cross-sectional view of a conventional printed circuit board.
An enlarged plan view of part A in the figure is shown. In Figures 3 and 4, 1
0 is an insulating board, 11 is a printed conductive foil arranged on the front surface of the board 10, 12 is a printed conductive foil arranged on the back side of the board 10, and 13 is a printed conductive foil that passes the board 10 through one end of the conductive foil 11 to the back side. A through hole 14 is formed at one end of the conductive foil 12 through the substrate 10 to the surface thereof, and the through holes 13 and 14 are formed adjacent to each other. 15 is a substrate 10 and a conductive foil 1
1, and is provided on the surface excluding the solder land portion 17 to which the solder 16 is attached. In the case of the illustrated example, the solder land portion 17 is formed around the entire opening (the entire periphery) of the surface of the through hole 13 . Reference numeral 18 denotes a resist film provided on the surfaces of the substrate 10 and the conductive foil 12, excluding the solder land portion 20 to which the solder 19 is attached.

In the illustrated example, the solder land portion 20 is formed on the surface of the through hole 14 all around the opening. A conductive wire 21 has one end 22 inserted into the through hole 13 from the front surface to the back surface of the substrate 10, and is clinched on the back surface. The other end 23 of the conductive wire is inserted into the through hole 14 of the substrate 1.
It is penetrated from the front side of 0 to the back side and clinched on the back side.

The intermediate portion 24 of the conductive wire 21 is connected to the substrate 1 between the through holes 13 and 14.
Extends to the surface of 0. Solders 16 and 19 are applied to solder lands 17 and 2 after both ends 22 and 23 of the conductive wire are clinched.
A conductive wire 21 is electrically connected to the conductive foils 11 and 12 via the solders 16 and 19.

Thereby, the conductive foils 11 and 12 are electrically connected via the conductive wire 21.

The conductive wire 21 has the function of electrically connecting the conductive foils 11 and 12 formed on the front and back surfaces of the printed circuit board.

Problems with the Prior Art Solder land portion 1 is soldered with solder 16 with the surface of the board 10 facing upward.
7 and one end 22 of the conductive wire, reflow soldering is performed by the method. The reflow soldering method involves applying cream solder to the surface of the solder land portion 17, melting the cream solder through a heating furnace, and then cooling and fixing the solder. However, when the cream solder melts, since the melted solder has fluidity, it flows out through the through hole 13 or one end portion 22 of the conductive wire inserted through the through hole 13.
There is a drawback that the amount of solder 16 that is fixed on the solder land portion 17 and the one end portion 22 for connection is insufficient, and the reliability of soldering is reduced.

Also, conductive foils 11 and 12 formed on the front and back surfaces of the substrate 10
When connecting using conductive wire 21, conductive foils 11 and 1 are connected to both ends 22 and 23 of conductive wire 21 via solders 16 and 19.
2 are connected. In this case, solders 16 and 19 are not formed on both sides of the same through hole 13 or 14, but are formed on one surface and the other back surface of adjacent through holes 13 and 14, as shown in FIG. . The reason for this is that if solders 16 and 19 are formed on both sides of the same through hole, for example 13 in FIG. 3, one end 22 of the conductive wire in FIG. The entire circumference of the back surface is closed with half 11]16. Then, there is no way for gas such as flux generated in the through hole 13 to escape, and it has no choice but to escape to the outside through the melted solder 16.

Therefore, a cavity is created due to the flux gas, and the solder 16
The adhesion becomes incomplete and the reliability of soldering is impaired.

Therefore, as shown in FIG. 3, the ends 22 and 23 of the conductive wire are connected by soldering using the adjacent through holes 13 and 14. However, according to this method, two through holes 13 and 14 are required, and there is a drawback that semi-opening cannot be performed on both sides of the same through hole, resulting in a decrease in the integration property.

Means for Solving the Problems In the present invention, a solder land portion formed on the upper surface of a through hole is formed on a part of the entire circumference of the through hole, and a conductor is made to extend over this solder land portion.

The number of solder lands formed on the front and back surfaces of the through hole was small (both sides were formed on a part of the entire circumference of the through hole).

Then, a conductor was soldered and connected to the solder lands formed on the front and back sides of this through hole.

When a conductor is placed on the solder land formed on a part of the circumference of the working through hole and soldered, the molten solder flows out through the through hole or the conductor inserted through the through hole. This can be prevented.

Furthermore, when solder is applied onto the solder land portion formed on a portion of the entire circumference of the through hole, the solder does not close the through hole. Therefore, an escape hole for gas such as flux is formed.

Embodiment FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is an enlarged plan view of section A in FIG. In Figures 1 and 2, the 3rd
The same parts as those in FIG. The novel point is that the mid-1 land portion 37 formed on the surface of the conductive foil 11 around the upper surface of the through hole 13 is formed only on a part of the extended side of the middle 24 of the conductive wire 21. That's true.

For this purpose, a resist film 1 is formed on the surface of the conductive foil 11.
5 is formed on the surface other than the solder land portion 37, and the third
A particular difference from the case shown in the figure is that a resist film 15 is formed on a part of the upper surface of the through hole 13 on the side opposite to the side where the intermediate portion 24 of the conductive wire 21 extends. The solder land portion 37 is preferably about half of the entire circumference of the upper surface of the through hole 13 . The solder 36 is attached to the solder land portion 37,
The conductive foil 11 and the intermediate portion 24 of the conductive wire are connected.

Another novel point is that a printed conductive foil 38 is also provided on the lower surface of the through hole 13, and a solder land portion 39 is formed on the surface of the conductive foil 38 all around the lower surface of the through hole 13. In addition, solder 40 is attached to this solder land portion 39.

The resist film 18 is formed on the back surface excluding the solder land portions 39 and 20. When the solder 36 is provided with the solder riding portion 37 facing upward, a reflow soldering method is generally used.

In this case, cream solder is applied to the surface of the solder land portion 37, and then passed through a heating furnace or the like to heat and melt the cream solder. Thereafter, the solder 36 is solidified by cooling. At this time, since the solder 36 is attached to the solder land portion 37 formed only on a part of the entire circumference on the upper surface of the through hole 13, the solder 36 in a molten state is inserted into the through hole 13 and the through hole 13. This prevents the conductive wire from flowing down through one end 22 of the conductive wire.

In addition, the solder lands 37, 39, and 20 are solder 36 and 40.
and 19 are all formed using the dip (flow) soldering method, or the solder 36 on the solder land 37 on the front surface is formed using the reflow soldering method, and the solder land 3 on the back surface is formed using the reflow soldering method.
When the solders 40 and 19 of 9 and 20 are formed by the dip soldering method, the solder 36 is not closed on the top surface of the through hole 13 and is opened, so when the solder 40 is formed, the through hole 1
Gas such as flux generated in the solder 3 can escape upward, and the soldering properties of the solders 40 and 36 are not adversely affected, and the reliability of the soldering is not impaired.

Furthermore, since the solders 36 and 40 can be formed on both sides of the through hole 13, the conductive foils 11 and 38 can be formed on both sides of the through hole 13, and the packaging density can be improved. That is,
In the conventional case of FIG. 3, when the conductive wire 24 is placed between the adjacent through holes 13 and 14, the solders 16 and 19 are provided only on one side of the through hole 13 and one side of the through hole 14. On the other hand, in the case of FIG. 1 of the present invention, the through hole 1
Solders 36 and 40 can be provided on both sides of the substrate 3 and on both sides of the through hole 14 as necessary, which is advantageous in terms of board design.

The conductor 4!21 can electrically connect the conductive foils 11 and 38 formed on both sides of the substrate 10, and can be provided at a lower cost than a through hole in which the inner surface of the through hole 13 is plated.

When applying solder 36 and 40.19 to both sides of the board 10,
The top surface can be soldered by the reflow method, and the bottom surface can be soldered by the dip method. When chip components or flat pack ICs are soldered to the top surface of the board, and components with lead wires are soldered to the bottom surface, without inverting the board 10. , can be done at the same time.

Effects of the Invention As described above, according to the present invention, a solder land portion is formed on a part of the entire circumference of the upper surface of the through hole, and a conductor is soldered thereon, thereby preventing solder from flowing down into the through hole. suppressed,
Highly reliable soldering can be performed. This is particularly effective when soldering is performed by reflow.

Even if the other end of the conductor is inserted into the through hole and soldered to the solder land formed around the entire circumference on the opposite side of the through hole, one end of the conductor is formed only on a part of the entire circumference of the through hole. It is soldered to the solder land part that has been soldered, the through hole is not blocked, gas such as flux can escape smoothly, and highly reliable double-sided soldering is possible, and it has the same function as a through hole. We can provide what we have at low cost.

When inserting both ends of a conductor into two adjacent through holes and soldering, it is possible to solder between the conductive foils on both sides of the board at both ends as necessary, and the conductor can be soldered between both sides of the board. The number of foils can be increased and the packaging density can be increased.

[Brief explanation of the drawing]

Figure 1 is a sectional view of one embodiment of the present invention, and Figure 2 is Figure 1A.
3 is a sectional view of the conventional example, and FIG. 4 is a sectional view of the conventional example.
It is an enlarged plan view of part A of the figure. 10...Insulating board, 13.14...Through hole, 37. Fist/O solder land part, 39.20/@fist solder land part, 21... Conductor, 22. Fist/one end part, 23...Other end. Figure 1 Figure 2

Claims (11)

[Claims] (1) An insulating substrate, a through hole drilled in the insulating substrate, a solder land portion formed in a part of the periphery of the hole on the upper surface of the through hole, and a conductive portion extending over the solder land portion. A printed circuit board comprising a body and solder connecting between the solder land portion and the conductor. (2) The method for manufacturing a printed circuit board according to claim (1), wherein the solder connection is performed by a reflow soldering method. (3) In a printed circuit board consisting of an insulating substrate, a through hole formed in the insulating substrate, and a solder land portion formed on the front and back surfaces of the through hole, the front and back surfaces of the through hole are A printed circuit board characterized in that one of the formed solder land portions is formed in all or part of the periphery of the through hole, and the other is formed in a part of the periphery of the through hole. (4) The printed circuit board according to claim (3), wherein a portion of the periphery of the through hole is formed to be approximately half of the periphery of the through hole. (5) The printed circuit board according to claim 1 or 2, wherein a conductor is inserted through the through hole, and the conductor is soldered to solder land portions formed on the front and back surfaces of the through hole. (6) In claim (5), one end of the conductor extends to another through hole bored in the insulating substrate adjacent to the through hole, and the surface of the other through hole or A printed circuit board characterized in that the printed circuit board is connected to another solder land portion formed on the back surface via another solder. (7) an insulating substrate, two through holes bored a predetermined distance apart in the insulating substrate, and holes formed all around each of the two through holes on the back surface of the insulating substrate; and a solder land portion formed in a portion around at least one of the two through holes on the surface of the insulating substrate. (8) In claim (7), one end of the conductor is inserted into one of the two through holes, the other end is inserted through the other of the two through holes, and the intermediate portion is disposed astride the two through holes. a wire, solder for connecting one end and the other end of the conductive wire to solder lands formed all around each of the through holes, and a middle portion of the conductive wire connected to the two through holes. and solder connected to a solder land portion formed on a portion of at least one periphery of the printed circuit board. (9) In claim (7), a solder land portion formed in a part of the periphery of at least one of the two through holes to which the intermediate portions of the conductive wires are connected by solder is a solder land portion formed around at least one of the two through holes. A printed circuit board characterized in that a portion of one periphery is a portion of an extended side of the intermediate portion of the conductive wire. (10) In claim (5), the conductor is soldered to a solder land formed on the surface of the through hole by reflow soldering, and the conductor is soldered to a solder land formed on the back surface of the through hole. A printed circuit board characterized in that the parts are soldered by a dip soldering method. (11) In claim (8), the print is soldered by dip soldering to a solder land portion formed entirely around the through hole, and is also formed on a part of the periphery of the through hole. Substrate manufacturing method.