JP2002026502A - Mounting substrate for mounting electronic parts with inserted lead - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting substrate which contains cream solder charged in advance in a through hole made in the mounting section of the substrate and does not reduce the quantity of the solder by not allowing the solder to fall down at the time of mounting electronic parts with inserted lead on the substrate. SOLUTION: In the through hole 1 of this mounting substrate B into which the lead of the electronic parts A with inserted lead is inserted, a shield body 7 is provided at the portion corresponding to the through hole 1 of a printing mask 6 used for screen printing the cream solder 2 so as to adjust the quantity of the solder 2 charged in the through hole 1 by means of the shield body 7. In addition, at the time of filling up the hole 1 with the solder 2, a lead inserting space 10 is provided. Particularly, spare solder 5 is arranged along the outer edge section of the opening of the through hole 1 into which the lead of the parts A is inserted on the rear surface of the substrate B opposite to the surface b1 of the substrate B on which the electronic parts A are mounted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insertion lead such as a large capacitor or a connector which is fixed by inserting a lead into a through hole provided on a mounting board and connecting the lead and the through hole by soldering. More particularly, the present invention relates to a mounting board in which cream solder is previously filled in a through hole into which a lead of an electronic component with an insertion lead is inserted.

[0002]

2. Description of the Related Art Conventionally, when mounting a capacitor or an electronic component with a lead on a mounting board, a through-hole is previously arranged on the mounting board, a lead is inserted into the through-hole, and the through-hole is soldered. The lead and the through-hole are connected and fixed by soldering so as to be filled with, so that conduction can be obtained.

[0003] Recently, with the improvement of various electronic components, the surface mounting of the electronic components has progressed, and the number of electronic components that can be mounted without using through holes has increased. For large and large electronic components, a bonding method is used in which leads are inserted into through holes and soldering is used due to the demand for bonding strength. Had been arranged.

[0004] However, since the work efficiency is very poor if the soldering work is performed in a separate step, recently, a cream solder used for joining a surface mount type electronic component to a mounting board surface has been used. When printing and arranging on the mounting board surface by screen printing, apply cream solder to the through holes where the leads of electronic components with insertion leads, such as connectors and large electronic components, are inserted. In advance, the through-hole is filled with cream solder, and then the lead of the electronic component with insertion lead is inserted into the cream solder filled in the through-hole, so that the electronic component with insertion lead is set on the mounting board, Along with other surface-mounted electronic components, the solder has been melted by passing it through a reflow furnace to melt the cream solder.

For the sake of convenience, electronic components mounted on a mounting board by inserting leads into through holes and soldering are collectively referred to as "electronic components with insertion leads". Distinction.

[0006]

However, the above-described method of mounting an electronic component with an insertion lead has the following problems.

First, there is no means for easily adjusting the amount of cream solder to be filled in the through-holes. When the cream solder is filled more than necessary, the melted solder is liable to drop during reflow. However, there is a problem that the amount of solder is insufficient.

Second, cream solder 2 'is filled in the through hole 1' of the mounting board B 'by screen printing (FIG. 8).
(A)) The lead a 'of the electronic component A' with the insertion lead was inserted into the cream solder 2 'filled in the through hole 1', and the electronic component A 'with the insertion lead was disposed on the mounting board B'. At this time, cream solder 2 'filled in through hole 1' leads a '
As a result, a large hollow portion 30 is formed in the through hole 1 '(FIG. 8 (b)). By melting the cream solder 2 'in a furnace, a part of the melted solder falls by its own weight (FIG. 8 (c)), and a shortage of solder occurs.

In addition, due to the formation of the hollow portion 30, the molten solder around the lead a 'is in a state where the molten solder is insufficient, and as shown in FIG. However, there was a problem that the '' could not be held by the solder 20, resulting in poor electrical bonding and poor bonding strength.

[0010]

In order to solve these problems, according to the present invention, there is provided a mounting method in which cream solder is filled by screen printing in a through hole of a mounting board into which a lead of an electronic component with an insertion lead is inserted. A shield is provided on a portion of the substrate corresponding to the through hole of the printing mask used for screen printing, and the amount of cream solder filled in the through hole by the shield is adjusted.

Further, in the mounting board on which the electronic component with the insertion lead is provided, the cream solder is filled in the through hole of the mounting board into which the lead of the electronic component with the insertion lead is inserted, while providing a lead insertion space. And

Further, preliminary solder is provided on the back side surface of the mounting surface of the electronic component with the insertion lead on the mounting substrate and along the outer edge of the opening of the through hole into which the lead of the electronic component with the insertion lead is inserted. I decided that.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a mounting board on which an electronic component with an insertion lead according to the present invention is provided, cream solder is applied by screen printing to a through hole provided for disposing the electronic component with an insertion lead. A shield is provided at a portion corresponding to the through hole of a printing mask used for screen printing to adjust the amount of solder to be filled, and the shape of the shield is adjusted. The amount of cream solder to be filled is adjusted.

By adjusting the amount of cream solder to be filled, it is possible to prevent the cream solder from being overfilled, and to prevent the molten solder from dropping during reflow and causing insufficient solder. be able to.

In particular, by providing the shield and filling the cream solder, the inside of the through hole is not completely filled with the cream solder. Is established,
It is easy to insert the lead.

Since the lead of the electronic component with an insertion lead is inserted into the lead insertion space, it is possible to prevent the cream solder in the through hole from being largely pushed out by the lead, and the cavity is formed in the through hole. Can be prevented from being formed, and a part of the molten solder can be prevented from dropping during the reflow of the cream solder.

[0017] Further, not on the surface of the mounting substrate on which the electronic components with insertion leads are disposed, but on the upper surface on the back side thereof, and along the outer edge of the opening of the through hole into which the leads of the electronic components with insertion leads are inserted. Solder to be used as spare solder is provided.

The preliminary solder may be cream solder, or may be melted once after the cream solder is provided. Alternatively, molten solder may be applied directly to the outer edge of the opening of the through-hole and disposed as a preliminary solder, or a plate-like solder may be processed to form a ring-shaped solder substantially matching the opening diameter of the through-hole, It may be arranged on the outer edge of the opening of the through hole and used as a preliminary solder.

By arranging spare solder on the outer peripheral portion of the through hole on the back side of the mounting surface of the electronic component with the insertion lead, when the mounting board on which the electronic component with the insertion lead is mounted is reflowed, The cream solder in the through-hole is melted, and the spare solder disposed at the outer edge of the through-hole is also melted, and the surface tension of the entire molten solder can be reduced by fusing with each other. Can be prevented from falling into a ball shape.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A mounting board B according to the present invention is a mounting board on which electronic components A with insertion leads such as large capacitors or connectors having large diameter leads or flat leads are provided. Since the capacitors and connectors described above need not only be mounted but also have required bonding strength, as shown in FIG. 1, a through hole 1 is provided on a mounting board B, and each lead is inserted into the through hole 1. Is inserted and joined by solder 20 (see FIG. 6).

The mounting board B of this embodiment is a glass epoxy board, and is a double-sided mounting type board in which wiring patterns are provided on both front and rear surfaces. The mounting board B is not limited to a glass epoxy board, but may be any insulating board on which the electronic component A with insertion leads is mounted. Further, it is not always necessary to mount on both sides, and it may be mounted on one side.

In this embodiment, the electronic component A with the insertion lead provided on the mounting board B is a connector, and the flat lead a is protruded from the back of the connector. The flat plate lead a has a rounded end, so that the flat plate lead a can be smoothly inserted into the cream solder 2 filled in the through hole 1 as described later (see FIG. 5). ).

FIG. 1 shows the mounting position of the connector on the mounting board B.
As shown in the figure, through holes 1 into which the flat leads a can be inserted are arranged corresponding to the positions of the flat leads a of the connector. A metal coating 3 such as copper is provided on the inner peripheral surface of the through hole 1 so that the flat lead a and the through hole 1 can be electrically connected via the solder 20 (see FIG. 7D )reference).

The opening of the through hole 1 on the side of the electronic component mounting surface b1 on which the insertion lead is provided b1 is formed along the outer edge of the opening.
A ring-shaped land 4a is provided, and an opening on the back surface b2 side of the mounting surface for electronic components with insertion leads, which is the back surface of the mounting surface b1 for electronic components with insertion leads, is formed along the outer edge of the opening. Two ring-shaped lands 4b are provided. First ring-shaped land 4a
The second ring-shaped land 4b is electrically connected via the metal film 3 (see FIG. 7A).

First, the cream solder 2 is printed by screen printing at a required position on the back surface b2 side of the mounting surface of the electronic component with insertion leads on the mounting board B with the back surface b2 side of the mounting surface of the electronic component with insertion leads facing upward. Then, the surface-mounted electronic components are arranged at required positions and passed through a reflow furnace, and the surface-mounted electronic components are mounted on the mounting board B.

In particular, the back surface b2 of the surface on which the electronic components with insertion leads
When the cream solder 2 is printed on the side, the cream solder 2 is also printed on the second ring-shaped land 4b at the same time, and the surface mounting type electronic component is mounted on the back surface b2 side of the mounting surface of the electronic component with the insertion lead. As shown in FIG. 2, the second ring-shaped lands 4b are covered with solder in accordance with the reflow performed for this purpose. The solder covering the second ring-shaped land 4b will be referred to as a preliminary solder 5.

Next, the mounting board B is turned upside down so that the electronic component mounting surface with insertion lead b1 faces upward, and cream solder 2 is printed by screen printing at a required position on the electronic component with insertion lead mounting surface b1. I have.

At the time of printing the cream solder 2 on the side b1 on which the electronic component with insertion lead is provided, the cream solder 2 is also filled in the through hole 1 into which the lead of the electronic component A with insertion lead is inserted. As shown in FIG. 3, printing is performed using a printing mask 6 that allows the cream solder 2 to be applied to required positions.

In particular, at this time, in the conventional case, a substantially circular print pattern substantially matching the outer diameter of the first ring-shaped land 4a is formed in a portion corresponding to the through hole 1 of the printing mask 6. However, in the present invention, the band-shaped shield 7 is disposed so as to cross the substantially center of the substantially circular print pattern. That is, the two substantially semicircular patterns 8, 8 face each other. In FIG. 3, reference numeral 9 denotes a gauze.

Printing of the cream solder 2 by superimposing a printing mask 6 having a through hole filling pattern consisting of two substantially semicircular patterns 8, 8 on the electronic component mounting surface b1 with insertion leads. Thus, as shown in FIG. 4, cream solder can be filled in the through hole 1 into which the lead of the electronic component A with the insertion lead is inserted, while providing the lead insertion space 10 (see FIG. 7B). .

That is, the cream solder 2 is not supplied to the portion where the shield 7 is provided, and the cream solder 2 to be printed is filled into the through hole 1 through the substantially semicircular pattern 8 portion. Due to the surface tension of the cream solder 2, the filled cream solder 2 has a through hole 1.
Is filled along the inner surface of the through hole, so that a slit-shaped lead insertion space 10 can be formed in the through hole 1.

By adjusting the width and the shape of the shield 7, the amount of the cream solder 2 to be filled, that is, the size of the lead insertion space 10 can be adjusted. If the width of the shield 7 is made too thin, the cream solders 2 filled in the through holes 1 are recombined with each other and lead insertion spaces 10 are formed.
Therefore, it is necessary to set the width of the shield 7 in accordance with the viscosity of the cream solder 2 to be used.

Further, by adjusting the position of the shield 7 and the width of the shield 7, the flat lead provided in the electronic component A with the insertion lead can be inserted into the lead insertion space 10 formed in a slit shape. a so that it can be inserted while fitting
A lead insertion space 10 is formed.

Even in the case where the lead provided on the electronic component A with insertion lead is not a flat lead a but a wire lead, a slit-shaped lead insertion space is formed in the same manner as described above.
Forming 10.

After filling the solder paste 2 into the through hole 1 while forming the lead insertion space 10, FIGS.
As shown in (c), the electronic component A with the insertion lead is disposed on the mounting board B by inserting the flat lead a of the electronic component A with the insertion lead into the lead insertion space 10 while fitting the same. .

Since the lead insertion space 10 is formed, the flat lead a pushes the cream solder 2 filled in the through hole 1 downward when the electronic component A with the insertion lead is disposed, and the through hole is formed. 1 can be prevented from forming a large hollow portion (see FIG. 8B).

The electronic component A with the insertion lead is disposed on the mounting board B, and the electronic component of the surface mounting type is disposed at the required position on the mounting surface b1 of the electronic component with the insertion lead.
After arranging each electronic component, it enters a reflow oven to melt the cream solder 2 and perform mounting. In FIG. 5, the state in which the electronic component A with the insertion lead is disposed on the mounting board B is a state viewed from the lower surface b2 side of the mounting surface of the electronic component with the insertion lead, which is the lower surface. Needless to say, reflow is performed with the arrangement surface b1 facing upward.

When the temperature reaches the reflow temperature in the reflow furnace, the cream solder 2 in the through-hole 1 is melted and becomes liquid molten solder. Surface tension acts on the molten solder, and the molten solder attempts to reduce the surface area as much as possible.

In the prior art, this action works on the molten solder composed of the cream solder 2 extruded from the through hole 1 and a part of the molten solder falls in a ball shape. There is no cream solder 2 extruded from the hole 1 and, furthermore, the pre-solder 5 which has been disposed on the second ring-shaped land 4b in advance and re-melted by reflow is present. And the melted cream solder 2 in the through hole 1 are fused, so that the surface tension can be reduced.

That is, since the surface area of the molten solder can be reduced by holding the molten solder by using the entire arrangement of the second ring-shaped lands 4b, it is possible to prevent the molten solder from dropping. it can. Therefore, it is possible to prevent the amount of solder from decreasing during reflow.

When the molten solder is taken out of the reflow furnace, the molten solder is re-solidified, so that the flat lead a of the electronic component A with insertion lead is securely secured by the solder 20, as shown in FIGS. Can be joined.

[0043]

According to the first aspect of the present invention, a shield is provided at a portion corresponding to a through hole of a printing mask used for screen printing, and the cream filled in the through hole by the shield. By adjusting the amount of solder, it is possible to prevent the overfilling of the cream solder into the through-holes, and to prevent the molten solder from dropping during reflow and causing insufficient soldering. it can. Furthermore, since the minimum required amount of cream solder can be filled, the amount of cream solder used can be reduced.

According to the second aspect of the present invention, in the mounting board on which the electronic component with the insertion lead is provided, the lead insertion space is provided in the through hole of the mounting board into which the lead of the electronic component with the insertion lead is inserted. When the electronic components with insertion leads are placed on the mounting board, the cream solder in the through holes is not pushed out by the leads when the electronic components with insertion leads are placed on the mounting board. The lead of the electronic component with an insertion lead can be disposed while being inserted into the lead insertion space without forming the lead. Accordingly, it is possible to prevent a part of the melted cream solder from dropping and reducing the amount of solder in the through-hole in the reflow process of the mounting board on which the electronic component with the insertion lead is attached.

According to the third aspect of the present invention, the upper surface on the back surface side of the mounting surface of the electronic component with the insertion lead of the mounting board,
Pre-soldering is provided along the outer edge of the opening of the through hole into which the lead of the electronic component with the insertion lead is inserted, so that when the mounting board on which the electronic component with the insertion lead is mounted is reflowed, the through hole is formed. The surface tension of the molten solder can be reduced by fusing the melted cream solder inside and the molten solder of the spare solder placed at the outer edge of the opening of the through hole. Can be prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory view illustrating a process of forming a mounting board according to the present invention.

FIG. 2 is an explanatory diagram illustrating a process of forming a mounting board according to the present invention.

FIG. 3 is an explanatory view illustrating a process of forming a mounting board according to the present invention.

FIG. 4 is an explanatory view illustrating a step of forming a mounting board according to the present invention.

FIG. 5 is an explanatory diagram illustrating a mounting state on a mounting board according to the present invention.

FIG. 6 is an explanatory diagram illustrating a mounting state on a mounting board according to the present invention.

FIG. 7 is an explanatory diagram for explaining a mounting step on a mounting board according to the present invention.

FIG. 8 is an explanatory diagram for explaining a mounting process on a conventional mounting board.

[Explanation of symbols]

 Reference Signs List A Electronic component with insertion lead B Mounting board a Flat lead b1 Mounting surface of electronic component with insertion lead b2 Rear surface of electronic component with insertion lead 1 Through hole 2 Cream solder 3 Metal coating 4a First ring land 4b Second Ring land 5 Spare solder 10 Lead insertion space 20 Solder

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Claims (3)

[Claims] 1. A mounting board in which cream solder (2) is filled by screen printing into a through hole (1) of a mounting board (B) into which a lead of an electronic component with an insertion lead (A) is inserted, A shield (7) is arranged at the part corresponding to the through hole (1) of the printing mask (6) used for screen printing, and the shield
Cream solder filled in through hole (1) by (7)
(2) The mounting board on which the electronic component with the insertion lead is arranged, wherein the mounting amount is adjusted. 2. A cream solder (2) is filled in a through hole (1) of a mounting board (B) into which a lead of an electronic component with an insertion lead (A) is inserted while providing a lead insertion space (10). A mounting substrate on which an electronic component with an insertion lead is provided. 3. The electronic component with an insertion lead on the side surface on the back side of the mounting surface of the electronic component with an insertion lead on a mounting board.
3. An electronic device with an insertion lead according to claim 1 or 2, wherein a spare solder (5) is arranged along the outer edge of the opening of the through hole (1) into which the lead of (A) is inserted. A mounting board on which components are placed.