JP2000307270A - Soldering method of printed wiring board - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the strength of solder joint between an earth land of a printed wiring board such as a television tuner and a shield case. SOLUTION: A copper paste 25 is applied to an end face of a printed wiring board so as to be connected to an earth land 22e arranged along an edge of the printed wiring board 20, and a copper-plated hardened layer 25h is heated. Generate Shield case 10C
The claw 12 formed by cutting the side wall of the printed wiring board is opposed to the edge of the earth land of the printed wiring board, and the ground land and the copper-plated hardened layer are connected to the claw 12 of the shield case and the solder joint Sd. In this case, the solder joint area corresponding to the copper-plated hardened layer is increased, and the strength of the solder joint is improved. More than the copper-plated cured layer 25h of the substrate 20H,
When the claw portion of the shield case is formed to be narrow, the solder wraps around to the end surface of the claw portion, and the solder joining strength is further improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for soldering a printed circuit board, which is suitable for, for example, fixing a printed circuit board of a television tuner to a shield case by soldering.

[0002]

2. Description of the Related Art Conventionally, in a block for handling a high-frequency signal, such as a television tuner, for preventing unnecessary radiation and induction and removing unnecessary coupling, as shown in FIG. A printed wiring board (so-called printed circuit board) 20 on which a required circuit is mounted is housed inside the shield case 10. In this specification, a printed wiring board is abbreviated as a substrate.

The substrate 20 is made of, for example, glass (fiber reinforced)
A conductor layer 22 such as a copper foil is attached to one surface of an insulating layer 21 made of epoxy resin, and a required pattern (not shown) is formed on the conductor layer 22 by etching.

Generally, the conductor layer 22 is covered with an appropriate coating material 23 called a solder resist except for a connection portion corresponding to a mounting position of a component.

The edge of the substrate 20 is formed into an appropriate shape such as a semicircle for connection with the shield case 10.
An area where the solder resist 23 is not applied is provided,
The conductor layer 22 is exposed in an appropriate shape, and a so-called earth land 22e is formed.

The plurality of earth lands and the side wall 10s of the shield case 10 are connected to the solder joints Sda, Sdb.
It is directly connected by {Sdj}.

As shown in FIG. 5, notches 11a and 11b are provided on the side wall of the shield
2, the nail 12 and the earth land 22e at the edge of the substrate 20 are opposed to each other at a predetermined position as shown by a two-dot chain line R, and are connected by a solder joint Sd.

Alternatively, as shown in FIG. 6, a rectangular notch 13 is provided on the side wall of the shield case 10W, and an “L” -shaped pin 14 is formed on the lower edge of the notch 13 and the substrate 20P A through hole 24 is formed in the earth land 22g at the end of the shield case 10W.
There is also a method of inserting the pin 14 on the side and connecting the earth land 22g and the solder joint Sd.

[0009]

By the way, in a block for handling a high-frequency signal, such as a television tuner, the solder joint between the shield case and the earth land of the substrate as described above is used for the electric circuit. Often forms a part.

[0010] However, for example, when a television tuner is incorporated into a television receiver and actually used, the temperature inside and outside of the television tuner rises and falls when the power is turned on and off. The solder joint between the substrate and the ground land receives thermal stress. This is due to the difference in the coefficient of thermal expansion between the shield case and the substrate.

[0011] When the solder joint between the shield case and the ground land of the board as described above is repeatedly subjected to thermal stress due to turning on and off of the power supply, solder cracks occur and the connection of the electric circuit is caused. Is cut off,
There has been a problem that a failure such as "no image" occurs in the television receiver.

As shown in FIG. 6, a method of soldering a pin formed in an "L" shape to an earth land of a substrate is to relieve stress at a solder joint portion by utilizing the elasticity of the pin. But it is not always enough.

In order to solve the above problems, it is conceivable that the shield case and the substrate are not electrically connected. However, in this case, there is a problem that the area of the substrate becomes large. Occurs.

Further, in a tuner for receiving a satellite broadcast having a high frequency (for example, a so-called BS tuner), there is a problem that an L-shaped pin becomes an electrical inductance, which is likely to cause a problem of poor design characteristics.

In view of the foregoing, an object of the present invention is to significantly improve the strength of solder joint between an earth land of a printed wiring board of a block for handling high-frequency signals, such as a television tuner, and a shield case. An object of the present invention is to provide a method for soldering a printed wiring board.

[0016]

According to a first aspect of the present invention, there is provided a method of soldering a printed wiring board, comprising the steps of: providing a shield case made of a conductive plate material and an edge of the printed wiring board; In the method of soldering a printed wiring board so as to fix the predetermined conductive region by soldering,
A copper paste is applied to an end surface of the printed wiring board connected to the predetermined conductive region in advance and subjected to a hardening process, and the hardened copper paste and the predetermined conductive region and the shield case are soldered and fixed. It is characterized by doing.

In the method for soldering a printed wiring board according to the first aspect of the present invention, the shield case and the predetermined conductive region of the printed wiring board are joined by soldering and applied to the end surface of the printed wiring board. The hardened copper paste and the shield case are joined by soldering, and the strength of the solder joint is remarkably improved.

According to a second aspect of the present invention, in the method for soldering a printed wiring board according to the first aspect, the shield case is formed so as to face the predetermined conductive region. The width of the joining claw portion in the edge direction is set to be smaller than the width of the predetermined conductive region.

In the method for soldering a printed wiring board according to the second aspect of the present invention, when a predetermined conductive region of the printed wiring board is soldered to a joining claw portion of the shield case, the end surface of the joining claw portion is extended. As the solder goes around,
The strength of the solder joint is further improved.

According to a third aspect of the present invention, there is provided a method for soldering a printed wiring board, wherein the locking pin formed on the shield case made of a conductive plate material is provided at a predetermined conductive area provided at an end of the printed wiring board. In a method of soldering a printed wiring board, in which a through-hole is engaged and the locking pin and the predetermined conductive region are fixed by soldering, a wall surface of the through-hole is cured by applying a copper paste in advance. The process is performed, and the hardened copper paste and the predetermined conductive region are fixed to the locking pin by soldering.

In the method for soldering a printed wiring board according to the third aspect of the present invention, the locking pin of the shield case and the predetermined conductive area of the printed wiring board are joined by soldering and penetrate the predetermined conductive area. The copper paste applied to the wall surface of the through hole and subjected to the hardening treatment and the shield case are joined by soldering, so that the strength of the solder joint is remarkably improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for soldering a printed wiring board according to the present invention will be described below with reference to FIGS.

[Embodiment] FIG. 1 shows a configuration of a main part of an embodiment of the present invention, and FIG. 2 shows a configuration of another main part.
In these figures, parts corresponding to those in FIG. 5 are given the same reference numerals, and a part of the description is omitted.

In this embodiment, as shown in FIG. 1A, a substrate 20 having an earth land 22e disposed along an edge is targeted. As shown in FIG. 1B, a copper paste 25 is previously applied to the end face of the substrate 20, and this copper paste 25 is subjected to a heat treatment as described below, as shown in FIG. Is generated. Thereafter, as shown in FIG. 2, the copper plated hardened layer 25h and the earth land 22e are fixed to the claws 12 formed on the shield case 10C by the solder joints Sd.

That is, in FIG. 1, a substrate 20 has a conductor layer 22 such as a copper foil attached to one surface of an insulating layer 21 made of, for example, glass epoxy resin.
Required pattern by etching (not shown)
Is formed.

The conductor layer 22 is covered with a solder resist 23, and a shield case 10
An earth land 22e is provided in an appropriate shape, for example, a semicircle, for connection.

In the copper paste application step, the substrate maker appropriately attaches an end face connected to the earth land 22e to the substrate 20 as shown in FIG. 1A as shown in FIG. The copper paste 25 is applied with a thickness of.

In the next copper paste curing step, for example, a heat treatment is performed for 3 to 5 minutes in a temperature range of 130 ° C. to 150 ° C., and the copper paste 25 shown in FIG. As shown in FIG.
5h are formed. When the heat treatment is performed at a temperature lower than 130 ° C., the copper paste is insufficiently hardened, and the copper plating becomes incomplete. When the heat treatment is performed at a temperature higher than 150 ° C., a problem such as oxidation of the earth land occurs.

Then, as shown in FIG. 1C, the earth land 2 of the substrate 20H on which the copper-plated cured layer 25h is formed.
2e and a shield case 10C as shown in FIG.
The claw portion 12 formed on the side wall is opposed to each other at the above-described predetermined position as shown in FIG. 2 and is connected by the solder joint portion Sd.

In the case of this embodiment, as shown in FIG. 2A, the claw portion 12 of the shield case 10C is provided on the ground land 22e of the substrate 20H similarly to the conventional example shown in FIG.
Are connected by a solder joint Sd, and in addition to the earth land 22e, a copper-plated hardened layer 25h formed on the end face of the substrate 20H is connected by the solder joint Sd.

Further, in this embodiment, as shown in FIG. 2B, the lower portion of the claw portion 12 of the shield case 10C is formed by the arc-shaped notches 12a and 12b from the copper-plated hardened layer 25h of the substrate 20H. Since it is formed narrow, the solder joint Sd extends to the end faces of the notches 12a and 12b and is connected to the copper-plated hardened layer 25h on the end face of the substrate 20H.

As a result, in this embodiment, the copper-plated hardening formed on the end face of the substrate 20H in the claws 12 of the shield case 10C is different from the solder joint area of the conventional example shown in FIG. The solder bonding area between the portion facing the layer 25h and the end face of the facing portion increases, and the solder bonding strength is remarkably improved. The solder connection strength increases as the board thickness increases.

When this embodiment is applied to, for example, a television tuner, solder cracks due to repetition of thermal stress as described above can be prevented, and the shield case and the earth land of the substrate can be prevented. , The market quality of a television receiver using a small tuner substrate is greatly improved.

[Other Embodiments] Next, another embodiment of a method for soldering a printed wiring board according to the present invention will be described with reference to FIG.

FIG. 3 shows the configuration of another embodiment of the present invention. In FIG. 3, portions corresponding to those in FIG. 6 are denoted by the same reference numerals, and a description thereof will be partially omitted.

In this embodiment, as shown in FIG.
The substrate 20Q in which the through-hole 24 is formed in the earth land 22g provided at the end is targeted.

That is, in FIG. 3, a substrate 20Q is formed, for example, by bonding a conductor layer 22 such as a copper foil to one surface of an insulating layer 21 made of glass epoxy resin and etching it to a required pattern (shown in FIG. 3). Is omitted).

The conductor layer 22 is covered with a solder resist 23. For example, a circular earth land 22 is provided at an end of the substrate 20Q for connection with the pin 14 of the shield case 10W.
g is provided, and a through hole 24 for inserting the pin 14 is formed in the earth land 22g.

In this embodiment, similarly to the above-described embodiment, a copper paste is applied to the end surface of the through hole 24 and a copper-plated hardened layer 26h is formed by a predetermined heat treatment such as reflow. Is done.

Thereafter, the pin 14 formed on the lower edge of the notch 13 on the side wall of the shield case 10W
Q through the through hole 24, the pin 14 and the earth land 22g, the copper-plated hardened layer 26h, and the solder joint S
fixed by d.

In the case of this embodiment, as shown in FIG. 3, the pins 14 of the shield case 10W are connected to the ground lands 22g of the substrate 20Q in the same manner as in the conventional example shown in FIG.
Are connected by the solder joint Sd, and in addition to the earth land 22g, the copper-plated hardened layer 26h formed on the end face of the through hole 24 is connected by the solder joint Sd.

Thus, in this embodiment, compared to the solder joint area of the conventional example shown in FIG. 6, the copper plating hardening formed on the end face of the through hole 24 of the pin 14 of the shield case 10W. The solder joint area of the portion facing the layer 26h increases, and the solder joint strength is remarkably improved. In addition,
This solder connection strength improves as the board thickness increases.

When this embodiment is applied to, for example, a television tuner, as described above,
The elasticity of the pins can reduce the thermal stress of the solder joint, so that solder cracks due to repeated thermal stress can be reliably prevented, and the electrical connection between the shield case and the ground land of the board Is ensured, the market quality of a television receiver using a small tuner substrate is remarkably improved.

[Other Embodiments] The above-described coating and curing of the copper paste can be carried out, for example, on a chip mounting line or a mount line of a maker of electronic equipment such as a television tuner.

In the chip mounting line, first, a copper paste is applied to the end face of the substrate, and then various chips are mounted at predetermined positions on the pattern of the substrate via cream solder or the like. Then, heat treatment for reflow (melting) of the cream solder is performed, so that the chip and the pattern of the substrate are joined by soldering, and the copper paste applied to the end face of the substrate is cured.

In the main line, first, various electronic components are mounted (mounted) at predetermined positions on a pattern of a substrate via cream solder or the like, and then a copper paste is applied to an end surface of the substrate. Then, in the reflow step of the main line, a predetermined heat treatment is performed, so that the electronic component and the pattern of the board are soldered and the copper paste applied to the end face of the board is hardened.

[0047]

As described above, according to the first aspect of the present invention, the strength of the solder joint between the substrate and the side wall of the shield case is significantly improved.

According to the second aspect of the present invention, the solder bonding strength between the substrate and the shield case side wall is further improved.

According to the third aspect of the present invention, the strength of the solder joint between the board and the locking pin on the shield case side is remarkably improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a main part of an embodiment of a method for soldering a printed wiring board according to the present invention.

FIG. 2 is a perspective view showing a configuration of another main part of the embodiment of the present invention.

FIG. 3 is a perspective view showing a configuration of another embodiment of the present invention.

FIG. 4 is a perspective view for explaining a conventional method of soldering a printed wiring board.

FIG. 5 is a perspective view for explaining another conventional example.

FIG. 6 is a perspective view for explaining another conventional example.

[Explanation of symbols]

10, 10C, 10W ... shield case, 12 ... claw part,
12a, 12b: Notch, 14: Pin, 20, 20
H, 20P, 20Q: printed wiring board (printed circuit board), 2
DESCRIPTION OF SYMBOLS 1 ... Insulating layer, 22 ... Conductor layer, 22e, 22g ... Earth land, 23 ... Solder resist, 24 ... Through-hole, 25 ... Copper paste, 25h, 26h ... Copper plating hardened layer, Sd ... Solder joint

Claims (3)

[Claims] A shield case made of a conductive plate material;
In a method of soldering a printed wiring board, wherein a predetermined conductive area provided at an edge of the printed wiring board is fixed by soldering, a copper paste is applied in advance to an end face of the printed wiring board connected to the predetermined conductive area. A method of soldering the printed circuit board, wherein the copper paste and the predetermined conductive region subjected to the curing process are soldered and fixed to the shield case. 2. The method of soldering a printed wiring board according to claim 1, wherein the width of the joining claw portion formed on the shield case in the edge direction so as to face the predetermined conductive region is set to the predetermined conductive value. A method for soldering a printed wiring board, wherein the width is set smaller than the width of the region. 3. A locking pin formed in a shield case made of a conductive plate material is engaged with a through-hole penetrating a predetermined conductive region provided at an end of the printed wiring board, and the locking pin and the predetermined pin are formed. In a method for soldering a printed wiring board, wherein a conductive region and a conductive region are fixed by soldering, a copper paste is applied in advance to a wall surface of the through hole, and a hardening process is performed. A method for soldering a printed wiring board, comprising soldering and fixing a predetermined conductive region and the locking pin.