JPH06112623A - Printed wiring board - Google Patents

Abstract

PURPOSE:To acquire a printed wiring board which enables thinning as a whole even if a chip component is mounted directly on a substrate. CONSTITUTION:A pair of plating through-holes 2 are formed in a substrate 1. A diameter D of the both plating through-holes 2 is 1.5 to 2.0 times a width L2 of a resistance element 4. A through-hole 5 for soldering 6 with the resistance element 4 fit in is provided between both plating through-holes 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board,
In particular, the present invention relates to a printed wiring board characterized by a structure for directly mounting a chip component such as a resistance element or a capacitor element on a base material.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional printed wiring board 30. A pair of pads 33 for mounting chip components are arranged in parallel on the surface of the base material 31 forming the printed wiring board 30. These pads 33 are connected to different signal lines (not shown) via separate wiring patterns 35.

FIGS. 6A and 6B show a state where a rectangular parallelepiped chip component 32 is directly mounted on such a printed wiring board 30. The chip component 32
Is, for example, a resistance element or a capacitor element. Further, electrodes 32 a for joining to the pads 33 are provided at both ends of this type of chip component 32.

When mounting this type of chip component 32,
First, cream solder 34 is applied on both pads 33, and each electrode 32 a of the chip component 32 is placed on each pad 33. Then, by heating and reflowing the solder 34, the chip component 32 is joined to both pads 33.

[0005]

However, when the chip component 32 is directly mounted on the printed wiring board 30 as described above, the following problems occur. That is, the entire printed wiring board 30 becomes thicker by the thickness of the chip component 32 (see FIG. 6B).

The present invention has been made in view of the above circumstances, and an object thereof is to provide a printed wiring board which can be thinned as a whole even when chip components are directly mounted. Especially.

[0007]

In order to solve the above-mentioned problems, the present invention provides a printed wiring board for directly mounting a chip component on a base material, wherein a base material is provided with a pair of through holes. The diameter is set to be larger than the width of the chip component, and an accommodating portion for soldering with the chip component fitted is provided so as to connect the through holes between the pair of through holes.

In this case, the accommodating portion is preferably formed so as to penetrate the base material.

[0009]

According to the present invention in which soldering is performed while the chip component is fitted in the accommodating portion, it is possible to reduce the thickness of the entire printed wiring board by the amount by which the chip component enters the base material.

Further, it is desirable that the accommodating portion is formed so as to penetrate the base material. The reason is that, in addition to being relatively easy to form by punching or the like, there is an advantage that burrs do not occur on the inner wall surface of the housing portion.

[0011]

EXAMPLE 1 Example 1 embodying the present invention will be described in detail below with reference to FIGS.

FIGS. 1A and 1B show a printed wiring board 10 of a first embodiment on which chip parts are mounted. In the first embodiment, the rectangular parallelepiped resistance element 4 is used as a chip component. The resistance element 4 is a so-called passive element including a resistor 4b and a pair of electrodes 4a provided at both ends thereof. The length L1, width L2, and thickness L3 of the resistance element 4 are about 2 mm, about 1 mm, and about 0.5 mm, respectively.

A pair of plated through holes 2 are arranged side by side on a base material 1 which constitutes the printed wiring board 10. A separate wiring pattern 3 is connected to each plated through hole 2. The wiring patterns 3 are connected to different signal lines (not shown). On the base material 1, a region other than the peripheral portion of the plated through hole 2 is covered with a solder resist (not shown).

As shown in FIG. 1 (a), both plated through holes 2 have a circular shape. In this case, the diameter D of the plated through hole 2 is 1.5 times the width L2 of the resistance element 4 or more.
It is preferably about twice. Plated through hole 2
If the diameter D is less than 1.5 times the width L2, the amount of the solder 6 in the plated through hole 2 becomes small, and the resistance element 4 cannot be reliably bonded. On the other hand, making the diameter D of the plated through hole 2 larger than twice the width L2 is not very preferable in achieving high density and fineness.

A through hole 5 as a housing portion is provided between both plated through holes 2 (see FIG. 2). The through hole 5 is formed to be slightly wider than the width L2 of the resistor 4b by punching or the like. The resistance element 4 is fitted inside the through hole 5, and the electrode 4 a of the resistance element 4 and the plated through hole 2 are joined by the solder 6.

As shown in FIGS. 1 (a) and 1 (b),
The distance S1 between the pair of plated through holes 2 is equal to the resistance element 4
Is set to be slightly smaller than the length L1. Therefore, when the resistance element 4 is fitted, both electrodes 4a are in a state of protruding into the plated through hole 2. On the other hand, the resistor 4b is laterally supported by the inner surface of the through hole 5.

Here, a method for manufacturing the above-mentioned printed wiring board 10 will be briefly described. When forming the plated through hole 2 in the base material 1, the through hole forming hole is first formed by, for example, drilling or punching. Next, the catalyst nuclei are applied in a state where the plating resist 7 is arranged at a predetermined position on the base material 1, and the electroless plating is further applied to the portion. Through this step, the plated through hole 2 and the wiring pattern 3 described above are formed.

Next, the portion located between both plated through holes 2 is removed by punching. Through this step, the through hole 5 is formed in that portion (see FIG. 2). Then, a solder resist is provided on a predetermined portion of the base material 1.

Now, the resistance element 4 is fitted into the accommodation groove 5 and the solder 6 is attached to each electrode 4a of the resistance element 4.
And each plated through hole 2 are electrically connected. That is, each plated through hole 2 plays a role as a chip component mounting pad in the conventional printed wiring board.

According to the structure of the printed wiring board 10, the resistance element 4 is completely fitted into the through hole 5 when the resistance element 4 is mounted. Therefore, it is possible to reduce the thickness of the resistive element 4 in the base material 1, that is, the entire thickness of the resistive element 4 by the thickness L3.

Further, the accommodating portion having the above-described shape can be formed relatively easily by punching or the like. In addition, there is an advantage that the inner wall surface does not have burrs. [Embodiment 2] Next, Embodiment 2 embodying the present invention will be described in detail with reference to FIGS.

FIGS. 3A and 3B show a printed wiring board 20 of the second embodiment on which chip parts are mounted. The chip component is the resistance element 4 having the same specifications as in the first embodiment.

The substrate 1 has a pair of plated through holes 1
2 are installed side by side. However, in the second embodiment, the shape of both plated through holes 12 is substantially oval, unlike the first embodiment. The maximum diameter d1 of the plated through hole 12 is 2.0 mm or more, and the minimum diameter d2 is 0.6 mm.

The maximum diameter d of the plated through hole 12 is
1 is preferably about 1.5 to 2 times the width L2 of the resistance element 4. The reason is that when solder 6 is attached, sufficient strength is secured, and at the same time, the plated through-hole 1
The reason for this is that the size of 2 does not hinder the refinement. Further, as shown in FIGS. 3 (a) and 3 (b), the spacing S2 between the plated through holes 12 is equal to the resistance element 4
Is set to be slightly smaller than the length L1.

A through hole 15 as a housing is provided between the plated through holes 12 (see FIG. 4).
The through hole 15 is formed in the resistor 4 by punching or the like.
Is formed to be slightly wider than the width L2.

With this structure, the resistance element 4 can be completely fitted in the through hole 15 as in the first embodiment. Then, each electrode 4 a of the resistance element 4 and each plated through hole 12 are electrically connected by soldering 6. Therefore, even with the configuration of the second embodiment, it is possible to reduce the overall thickness of the resistance element 4 by the thickness L3.

Further, according to the configuration of the second embodiment in which the plated through hole 12 has an oval shape, the inner wall surface of the plated through hole 12 and both end surfaces of the resistance element 4 are substantially parallel to each other. Therefore, the adhesion of the solder 6 to those portions is improved and the joint strength is improved. Further, when such plated through holes 12 are adopted, both plated through holes 12 can be formed close to each other, so that it is possible to mount a smaller resistance element 4. Therefore, it is extremely convenient for achieving high density and fineness of the printed wiring board 20.

The present invention is not limited to the first and second embodiments, but can be modified, for example, as follows. (A) It is possible to mount not only a rectangular parallelepiped chip component as in the first and second embodiments but also a cylindrical one.

(B) In addition to the resistance element, passive elements such as a capacitor element and an inductance element can be mounted. (C) The accommodating portion does not necessarily have to be the through holes 5 and 15 as in the first and second embodiments. For example, it may be a non-penetrating accommodating portion formed by performing a spot facing process between the plated through holes 2 and 12 from the upper surface of the base material 1.

(D) When forming the accommodating portion, any method other than punching can be adopted. (E) The accommodating portion may be formed by a procedure in which a pair of through holes and a through hole are first formed, then the portion is plated, and then only the plated portion of the through hole is removed. .

(F) The present invention can also be applied to the case of one chip component having two or more resistors and three or more electrodes.

[0032]

As described above in detail, according to the printed wiring board of the present invention, since the chip parts are put into the base material after mounting, it is possible to reduce the thickness as a whole. Produce the effect.

[Brief description of drawings]

FIG. 1A is a partially enlarged plan view showing a state in which a resistance element is mounted on a printed wiring board of Example 1, and FIG. 1B is a sectional view taken along the line AA of FIG.

FIG. 2 is a partially enlarged plan view showing the printed wiring board of Example 1.

3A is a partially enlarged plan view showing a state in which a resistance element is mounted on the printed wiring board of Example 2, and FIG. 3B is a sectional view taken along line BB of FIG. 3A.

FIG. 4 is a partially enlarged plan view showing a printed wiring board of Example 2.

FIG. 5 is a partially enlarged plan view showing a conventional printed wiring board.

6A is a partially enlarged plan view showing a state in which a resistance element is mounted on the printed wiring board of FIG. 5, and FIG. 6B is a sectional view taken along line CC of FIG.

[Explanation of symbols]

1 base material, 2 (plating) through hole, 4 resistance element as chip part, 5,15 through hole as accommodating part, 10, 20 printed wiring board, width of L2 chip part, diameter of D through hole, d1 through The (maximum) diameter of the hole.

Claims (2)

[Claims] 1. A printed wiring board for directly mounting a chip component on a base material, wherein a base material is provided with a pair of through holes, the diameters of which are set larger than the width of the chip component, and the chip component is fitted. A printed wiring board, characterized in that an accommodating portion for soldering is provided between the pair of through holes in such a state that both through holes communicate with each other. 2. The printed wiring board according to claim 1, wherein the housing portion penetrates the base material.