JP2003124617A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board on which an electronic component of either an insertion type or surface mount type can be mounted without lowering the joining strength of the electronic component of the surface mount type. SOLUTION: Through holes 30 are formed nearby through holes 10 which are formed in the insulating substrate 1 for the printed wiring board and into which lead terminals of the electronic components can be inserted and through hole lands 31 of the through holes 30 are formed integrally with lands 11 of the through holes 10.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a printed wiring board.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing a state in which an insert-type electronic component is mounted on a dedicated printed wiring board for mounting the insert-type electronic component.

The lead terminal 5 of the electronic component 550 is mounted on the printed wiring board 506 on which the insertable electronic component 550 is mounted.
Through-holes 510 (inner wall surface of which is plated with copper) are formed for soldering 51.

Lands 511 made of copper foil or the like are formed around the through holes 510 on the front and back surfaces of the printed wiring board 506.

The lead terminal 551 of the electronic component 550 is inserted into the through hole 510 and then placed in a flow furnace, and molten solder is jetted from below the printed wiring board 506 to a surface opposite to the surface on which the electronic component 550 is mounted. The molten solder is applied and the through holes 510 are filled with the solder.

After that, the electronic component 540 is soldered to the through hole 510 and the land 511 by cooling and solidifying the solder.

[0007]

By the way, in recent years, as the demand for electronic components has increased, the supply of electronic components has often become unsuccessful. In order to avoid this situation, products have been commercialized in which electronic components having the same performance and characteristics electrically can be used as alternative components.

FIG. 9 is a sectional view showing a state in which the surface mount type electronic component is mounted on a dedicated printed wiring board for mounting the insert type electronic component.

This surface mount type electronic component 540 is
A lead terminal of a P (Dual Inline Package) type insertion type electronic component is bent into a J shape, and S
This is an OJ (Small Outline J lead) type surface mount electronic component.

When the SOJ type surface mount type electronic component 540 is soldered to the printed wiring board on which the DIP type insertion type electronic component is mounted, the through hole 510 is used.
Since the inner wall of the solder has copper plating, the molten solder spreads on the inner wall of the solder and the solder fillet 502a cannot have a sufficient height, and the lead terminal 551 and the land 511 cannot be obtained.
There is a problem that the bonding strength with

The present invention has been made in view of the above circumstances, and its object is to mount both insertion-type and surface-mounting type electronic components without lowering the bonding strength of the surface-mounting type electronic components. It is to provide a printed wiring board that can be manufactured.

[0012]

In order to solve the above-mentioned problems, the invention according to claim 1 provides an insulating substrate for a printed wiring board,
A plurality of through-holes formed on the printed wiring board insulating substrate, into which terminals of insertable electronic components can be inserted, and formed on both front and back surfaces of the printed wiring board insulating substrate, surrounding both ends of the through-holes, respectively. And two lands positioned so as to

Here, the through hole is a hole penetrating from the front side to the back side of the insulating substrate for a printed wiring board, and the inner wall thereof has no coating such as copper plating and the substrate material itself is exposed. . For example, when soldering a terminal of a surface-mount type electronic component to a land, the inner wall surface of the through hole is not plated, so molten solder does not flow into the through hole, and the terminal is securely attached to the footprint. A solder fillet having a predetermined height required for joining is formed on the land.

According to a second aspect of the present invention, in the printed wiring board according to the first aspect, a through hole is formed in the vicinity of the through hole, and the land of the through hole is formed in the through hole land of the through hole. It is characterized by being integrally formed.

Lands on the front surface and the back surface of the printed wiring board are electrically connected to each other through the through holes.

According to a third aspect of the present invention, in the printed wiring board according to the second aspect, a footprint for fixing a terminal of a surface mount type electronic component is integrally formed on at least one of the two lands of the through hole. It is characterized by being formed.

The terminals of the surface mount type electronic component can be soldered not only to the land but also to a footprint formed integrally with the land.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a land and a footprint of a printed wiring board according to an embodiment of the present invention.

A through hole 10 into which an insertable electronic component can be inserted is formed in an insulating substrate 1 for a printed wiring board (see FIG. 6) which constitutes a printed wiring board.

The lands 11 of the through holes 10 are arranged symmetrically with respect to the reference line CL.

The land 11 is integrally formed with a footprint 20 for soldering terminals of a surface mount type electronic component.

The footprint 20 extends in a direction orthogonal to the pitch direction of the through holes 10.

Further, through holes 30 are arranged in the printed wiring board insulating substrate 1 in the vicinity of the through holes 10 symmetrically with respect to the reference line CL.

Through hole land 3 of through hole 30
1 is a land 1 of the through hole 10 through the footprint 20
It is formed integrally with 1.

The lands 11 are located at both ends of the through hole 10, and the through hole lands 31 are located at both ends of the through hole 30, respectively.

The pitch Pf of the footprint 20 and the pitch Pt of the through holes 10 are equal.

FIG. 2 shows the front side of the printed wiring board.
3 is a partially enlarged view of FIG. 1, and FIG. 3 is a partially enlarged view of FIG. 1 showing the back surface side of the printed wiring board.

Only the shape of the footprint differs between the front surface side and the back surface side of the printed wiring board.

The land 11 is formed concentrically with the through hole 10. The through hole land 31 is formed concentrically with the through hole 30.

When the diameter of the land 11 and the diameter of the through hole 10 are C and G, there is a relationship of C = G + 0.6 (unit: mm). The diameter C of the land 11 is the footprint 20
Is greater than the width F.

The footprints 20 and 25 are substantially rectangular. The front surface footprint 20 connects the land 11 and the through hole land 31 and extends from the through hole 10 in a direction approaching the reference line CL. The land 11, the through hole land 31, and the footprint 20 are formed by copper foil or copper plating.

Further, the footprint 25 on the back side connects the land 11 and the through hole land 31. The land 11, the through hole land 31, and the footprint 25 are formed by copper foil or copper plating.

The width of the footprint 20 is F and the width of the lead terminal (terminal) 41 of the electronic component 40 (see FIG. 4) is W1.
Then, there is a relationship of W1 = F (unit: mm).

In general, the diameter C of the land 11 is 0.4 to 0.6 mm larger than the diameter G of the through hole 10, and the length E of the footprint 20 is 0 to more than the length of the lead terminal 41.
1.6 mm larger, the diameter D of the through hole 30 is 0.7
The diameter of the through hole land is 1.
It is set to 35 mm to 1.45 mm.

FIG. 4 is a perspective view of an SOJ type surface mount type electronic component.

This SOJ type surface mount type electronic component 40 is obtained by bending the lead terminals 51 of the DIP type insertion type electronic component 50 (see FIG. 5) in a J-shape toward each other as described above. (However, lead terminal 4
1 and the lead terminal 51 have different tip shapes).

FIG. 5 is a perspective view of a DIP type insertion type electronic component.

This DIP type insertion type electronic component 50
The pitch Ptd of the lead terminals 51 of the SOJ shown in FIG.
The pitch Pfd of the lead terminals 41 of the surface mount type electronic component 40 is equal to the pitch Pfd.

The pitch Ptd of the lead terminals 51 is equal to the pitch Pt of the through holes 10, and the pitch Pfd of the lead terminals 41 is equal to the pitch Pf of the footprint 20.

FIG. 6 is a sectional view showing a state in which a SOJ type surface mount type electronic component is mounted on a printed wiring board.

SOJ type surface mount type electronic component 40
When mounted on a printed wiring board, the cream solder 2 is first printed on the footprint 20 by screen printing using a metal mask.

Next, the lead terminal 41 of the electronic component 40 is placed on the predetermined footprint 20.

In this state, the electronic parts 4
0 or the entire printed circuit board is heated to a temperature at which the cream solder 2 melts.

After that, the lead terminals 41 are formed in the footprint 20 by cooling and solidifying the cream solder 2.
Is soldered to (see FIG. 6).

At this time, since the solder 2 does not wet and spread in the through hole 10, the solder fillet 2a having a height sufficient to secure the required bonding strength between the lead terminal 41 and the footprint 20 is formed. It

FIG. 7 is a sectional view showing a state in which a DIP type insertion-type electronic component is mounted on a printed wiring board.

When mounting the DIP type insertion-type electronic component 50 on the printed wiring board, first, the lead terminals 51 of the electronic component 50 are inserted into the through holes 10.

Next, the printed wiring board is sprayed with flux from the surface opposite to the surface on which the electronic component 50 is mounted.

In this state, it is put in a flow furnace, and molten solder is jetted from below the printed wiring board 1 to apply the molten solder to the surface opposite to the surface on which the electronic component 50 is mounted.

Thereafter, the lead terminals 51 are soldered to the lands 11 on the surface opposite to the surface on which the electronic component 50 is mounted by cooling and solidifying the solder (see FIG. 7).

At this time, the lead terminal 51 and the electronic component 50
A solder fillet 2a having a height sufficient to secure the required bonding strength between the surface on which the solder is mounted and the footprint 25 on the opposite surface is formed.

Since the front surface and the back surface of the printed wiring board are electrically connected to each other through the through hole 30, the through hole land 31, and the footprint 20, it is ensured that the front surface and the back surface of the printed wiring board are electrically connected. Become.

The embodiments of the present invention will be described in more detail below.

In this embodiment, the printed wiring board 1 having a length of 100 mm, a width of 60 mm and a thickness of 1.6 mm was used. Twenty pairs of footprints 20 (see FIG. 1) are formed on the printed wiring board 1.

In this embodiment, the diameter C of the land 11 is
The diameter D of the through hole 10, the length E of the footprint 20 and the width F of the footprint 20 are each 1.4 m.
m, 0.8 mm, 3.4 mm and 1.2 mm (see FIG. 2).

A method of mounting the SOJ type surface mount type electronic component 40 on this printed wiring board will be described.

First, a 0.15 mm-thick stainless steel metal mask having an opening having the same shape as the footprint 20 is superposed so that the opening and the footprint 20 are aligned with each other.

Next, using the printing machine, the footprint 2
0 solder particles with a diameter of 40 μm (63% Sn-37% P
The cream solder 2 in which b) and flux (solvent, rosin, thixotropic agent, activator, etc.) are kneaded at a weight ratio of about 85:15 is screen-printed.

After removing the metal mask, 20 S
Each of the OJ type surface mount electronic components 40
It mounts on a printed wiring board using a mounting device so that the corresponding lead terminals 41 of a pair and footprint 20 may correspond.

The longitudinal length L1 and the lateral length L of the package of this SOJ type surface mount type electronic component 40.
2, the number of lead terminals, the lead terminal width W1, the lead terminal pitch Pfd and the distance S1 between the opposing lead terminals are 19 mm, 6.4 mm, 7 pairs, 1.2 mm and 2.54 m, respectively.
m and 6.0 mm (see FIG. 4).

Next, the printed wiring board on which the electronic component 30 is mounted is placed on a conveyor having a moving speed of 1 m / min, and a predetermined temperature profile (for example, preheat temperature 150 ° C.,
The electronic component 4 was passed through a reflow furnace set to a peak temperature of 230 ° C (50 ° C higher than the melting point of solder, 180 ° C).
0 or the entire printed circuit board is heated to a temperature at which the cream solder 2 melts.

After that, the cream solder 2 is cooled to room temperature and solidified, so that 20 SOJ type surface mount type electronic components 40 are soldered to the printed circuit board.

The height H of the solder fillet 2a was measured for these 20 soldered surface mount type electronic components 40 of SOJ type. As a result, the height H of the solder fillet 2a was 0.5 mm or more. It was confirmed that sufficient bonding strength could be obtained.

Next, a method of mounting the DIP type insertion-type electronic component 50 on the printed wiring board 1 will be described.

Twenty DIP type insertion-type electronic components 50 are mounted on a printed wiring board using a mounting device so that seven pairs of corresponding lead terminals 51 are inserted into the through holes 10.

This DIP type insertion type electronic component 50
The length L3 of the package in the longitudinal direction, the length L4 in the lateral direction,
Number of lead terminals, lead terminal width W2, lead terminal pitch P
td and the distance S2 between the opposing lead terminals are each 19
mm, 6.4 mm, 7 pairs, 0.65 mm, 2.54 mm
And 7.62 mm (see FIG. 5).

Next, the printed wiring board on which the electronic component 50 is mounted is placed on a conveyor at a moving speed of 1 m / min, and flux (solvent, rosin, thixotropic agent, Activator etc.) is sprayed.

The printed wiring board has a predetermined temperature profile (for example, a preheat temperature of 100 ° C. and a solder bath temperature of 240).
The molten solder is jetted from below the printed wiring board to pass the molten solder on the surface opposite to the surface on which the electronic component 40 is mounted.

Thereafter, the solder is cooled to room temperature and solidified, so that 20 DIP type insertion-type electronic components 50 are soldered to the printed circuit board.

These 20 soldered DIP type insertion-type electronic components 50 were solder fillet 2
As a result of measuring the height H of a, the height H of the solder fillet 2a was 0.7 mm or more, and it was confirmed that sufficient bonding strength could be obtained.

According to the printed wiring board of this embodiment,
Both the DIP type insertion type electronic component 50 and the SOJ type surface mount type electronic component 40 can be soldered with sufficient bonding strength.

Even if the length of the surface mount electronic component 40 in the widthwise direction is different from the length of the insertion type electronic component 50 in the widthwise direction, the surface mount electronic component 40 is mounted on the printed wiring board. can do.

In the above embodiment, the land 1
Footprint 20 with 1 as a concentric circle with through hole 10
Is rectangular, but the land 11 may be elliptical and the footprint 20 may be polygonal (triangular, pentagonal, etc.).

When the SOJ type surface mount type electronic component 40 is mounted on the printed wiring board, the lead terminal 4
1 is placed on the through hole 10, but the lead terminals 41 are placed on the footprint 20 (on the side close to the reference line CL with the through hole 10 in between, on the far side and on both sides with the through hole 10 in between). May be.

Further, in the above embodiment, the through hole 30 is used.
Although it is formed integrally with the land 11 via the footprint 20, the through hole 30 may be formed directly with the land 11.

The diameter C of the land 11 is 0.4 to 0.6 mm larger than the diameter D of the through hole 10, and the length E of the footprint is 0 to 1.6 mm larger than the length of the lead terminal.
The through hole 30 has a large diameter D of 0.7 mm to 0.
9mm, diameter of through hole land is 1.35mm ~
It is preferably set to 1.45 mm, but is not limited to this setting range.

Further, in the above embodiment, the printed wiring board of the present invention has a DIP (Dual Inline Pack).
In the above description, the electronic component of the (age) type is mounted, but for example, SIP (Single Inline Pa
The present invention can also be applied to the case of mounting an electronic component of a package type.

[0079]

As described above, according to the printed wiring board of the present invention as set forth in claim 1, the insertion type and surface mounting type electronic components can be performed without lowering the bonding strength of the surface mounting type electronic components. Any of these can be installed.

According to the printed wiring board of the second aspect of the present invention, it is possible to ensure conduction between the front surface and the back surface of the printed wiring board.

According to the third aspect of the printed wiring board of the present invention, even if the length of the surface mount type electronic component in the lateral direction is different from that of the insertion type electronic component, the electronic component is Can be soldered.

[Brief description of drawings]

FIG. 1 is a perspective view showing a land and a footprint of a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG. 1 showing a front surface side of a printed wiring board.

FIG. 3 is a partially enlarged view of FIG. 1 showing a back surface side of a printed wiring board.

FIG. 4 is a perspective view of an SOJ type surface mount electronic component.

FIG. 5 is a perspective view of a DIP type insertion-type electronic component.

FIG. 6 is a cross-sectional view showing a state in which an SOJ type surface mount type electronic component is mounted on a printed wiring board.

FIG. 7 is a cross-sectional view showing a state in which a DIP type insertion-type electronic component is mounted on a printed wiring board.

FIG. 8 is a cross-sectional view showing a state in which an insert-type electronic component is mounted on a dedicated printed wiring board for mounting the insert-type electronic component.

FIG. 9 is a cross-sectional view showing a state in which a surface-mounted electronic component is mounted on a dedicated printed wiring board on which an insertion-type electronic component is mounted.

[Explanation of symbols]

1 Insulation board for printed wiring board 10 through holes 11 lands 20,25 footprint 30 through holes 31 Through Hole Land

Claims (3)

[Claims] 1. An insulating substrate for a printed wiring board, a plurality of through holes formed in the insulating substrate for a printed wiring board, into which terminals of an insertable electronic component can be inserted, and front and back surfaces of the insulating substrate for a printed wiring board. Formed on both sides,
Positioned so as to surround both ends of the through hole 2
A printed wiring board having two lands. 2. The print according to claim 1, wherein a through hole is formed near the through hole, and the land of the through hole is integrally formed with a through hole land of the through hole. Wiring board. 3. The printed wiring according to claim 2, wherein a footprint for fixing a terminal of a surface mount type electronic component is integrally formed on at least one of the two lands of the through hole. Board.