JPS62156899A - Printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a printed wiring board, and particularly to a printed wiring board constructed by laminating a plurality of completed printed wiring boards, such as a flexible printed wiring board.

[Technical front of the invention and its problems]

A multilayer printed wiring board is constructed by stacking a plurality of flexible printed wiring boards because it is cheaper than a multilayer printed wiring board. In this structure, a land is provided in the insertion hole and a conductor having a predetermined wiring pattern is connected to this land in order to establish an electrical connection with the leads of electronic components, etc. .

In such a multilayer printed wiring board, lands are conventionally provided in the lead insertion holes not only in the wiring board layer that requires electrical connection, but also in the printed wiring board layer that does not require electrical connection. There is. Then, these printed wiring board layers are stacked with the lead insertion holes aligned, and electrical connection with component leads is achieved through lands provided in the insertion holes. In such a configuration, soldering is performed well on the lands close to the surface, but as the printed wiring board layer approaches the component surface, it becomes difficult for lυ to flow into the interior through the insertion hole, making it difficult to solder inside. If there is a wiring board layer that requires continuity, soldering may not be done in that area, resulting in poor continuity.

FIG. 2 is a sectional view showing a state in which electronic components are inserted into a conventional printed wiring board. In the example shown in Figure 2, the printed wiring board has a four-layer structure consisting of four flexible printed wiring boards 3-1.3-2.3-3.3-4. Lands 4 are provided at each insertion hole portion of the plate layer.

Insert the lead 2 extending from the electronic component body 1 into the insertion hole, and pour the solder 7 using a soldering iron with the printed wiring board 3-1 side facing up, or use flow solder on the printed wiring board 3-1 side. The land 4 and the lead 2, which require electrical continuity, are connected by contacting each other and filling the insertion hole with solder 7.

In the example shown in FIG. 2, the printed wiring board layers that require electrical connection are wiring board layer 3-1 in section A, wiring board layer 3-2 in section B, and wiring board layer 3-2 in section 0. Board layers 3-4 correspond to this, and wiring patterns 6-1.6-2.6 are installed on the lands of these wiring board layers that require electrical connections.
-4 are connected to each other.

Note that an insulating layer 5 is provided between each of the wiring board layers 3-1 to 3-4 for adhering the wiring board layers and insulating them. When soldering the wiring board layer 3-1 which requires an electrical connection to the beam 2 in the Δ section, the connection is easily made because it is closest to the beam 7. However, in part B and part 0, the wiring board layers 3-2 and 3-/4, which require electrical connections, are respectively the second and fourth layers from whichever side the solder is soldered. Therefore, during soldering, the solder 7 does not fully penetrate into the insertion hole due to surface tension, resulting in soldering defects.
The connection may not be sufficient. As described above, the conventional printed wiring board has the disadvantage that the electrical connection between the leads and the lands is not sufficient in the printed wiring board layer on the component side.

(Object of the Invention) The present invention has been made in consideration of the above circumstances, and provides a printed wiring board having a V4 layer structure between a printed wiring board layer that requires electrical connection and a lead of an electronic component to be mounted. The purpose of the present invention is to provide a printed wiring board on which reliable connection can be made without causing soldering defects.

[Requirements for invention]

In the printed wiring board according to the present invention, at least one first printed wiring board layer that requires electrical connection with the leads of electronic components mounted thereon and at least one second printed wiring board layer that does not require electrical connection are provided. The printed wiring board layer of the second printed wiring board layer is stacked with the lead insertion holes aligned, and an electrical connection is made through the land provided in the lead hole, and the insertion hole of the second printed wiring board layer is aligned with the lead insertion hole. It is characterized in that it is formed slightly larger than that of the first printed wiring board layer, and that the land is provided only on the first printed wiring board layer.

This allows the solder to sufficiently penetrate into the component insertion hole, making it possible to establish a reliable method.

[Embodiments of the invention]

The present invention will be described in detail below based on illustrated embodiments.

FIG. 1 shows one embodiment of the present invention, and is a sectional view showing a state in which electronic components are mounted on a printed wiring board according to the present invention.

The printed wiring board according to the present invention has a structure similar to that shown in FIG.
The printed wiring board layer of layers 8-1.8-2.8-3.8-4. Similar to the conventional structure shown in FIG. In the wiring board layer 8-4, the wiring board 2 is connected to the wiring board layer 8-4.

However, unlike the conventional structure, each wiring board layer is provided with lands 10 only at the portions where connections with leads 2 are made. However, in part A, a land 10-1 connected to the wiring conductor 9-1 is provided only in the insertion hole of the wiring board layer 8-1, and the land 10-1 connected to the wiring conductor 9-1 is provided only in the insertion hole of the wiring board layer 8-1.
No land is provided at 2.8-3° and 8-4. Similarly, in part B, the land 10 is only on the wiring board layer 8-2.
-2 is provided. In addition, in part 0, wiring board layer 8
A land 10-4 is provided only on -4. In addition, the insertion 7L11 of the wiring board layer that does not require electrical connection in the wiring board layer where the land 4 is not provided is formed to be slightly larger than the inner diameter of the land of the wiring board layer that requires electrical connection. . The reason why the component insertion hole is made large as a whole is to facilitate manual visual confirmation or to facilitate contact of the land portion with flow solder or the like.

At the same time, with the lead 2 of the electronic component 1 inserted into the insertion hole, the land 10 of the wiring board layer that requires electrical connection
can be observed from the outside. Therefore, when the lead 2 of the electronic component 1 is inserted into a predetermined insertion hole and the Iυ solder 7 is manually flowed in from the upper layer, the solder 7 flows inside and reaches the land 4. It becomes easy to confirm that the solder damage has occurred between the lead 2 and the lead 2. Note that the inner diameter of the component insertion hole 11 is smaller than the outer diameter of the standoff 12 of the component to be mounted, so that the component can be fully supported.

In this way, in the printed wiring board according to the present invention, lands are provided only in the wiring board layers that require electrical connection, and the size of the insertion holes is slightly larger than that in the wiring board layers that require electrical connection. Since the solder is formed to be thick, it is easy for the solder to flow in, and it is possible to reliably reach the necessary land and connect with the lead.

In the above embodiments, a flexible printed wiring board is assumed as the printed wiring board to be laminated, but the invention is not limited to this, and an intermediate layer or a double-sided rigid printed wiring board can be used.

〔Effect of the invention〕

As explained above based on the embodiments, in the present invention, the electrical in-contact between the land and the lead can be achieved by /υ bonding, so that the printed wiring board with the multilayer structure is inexpensive and easy to use. It becomes possible to provide

In particular, conventional flexible printed wiring boards with a laminated structure of three or more layers were provided with integral through-holes, but 1! J8 is tight and difficult, resulting in an increase in the 111 value of the printed wiring board, but by adopting the structure according to the present invention, it becomes possible to form a printed wiring board at an extremely low cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a printed wiring board according to an embodiment of the present invention, and FIG. 2 is a sectional view showing an example of a conventional printed wiring board. 1...Electronic component, 2...Lead, 4...Land,
7...Solder, 8-1.8-2.8-3.8-4...
- Printed wiring board layer, 11... component insertion hole. Applicant's agent Sato-O A B C Figure 1 Figure 2

Claims (1)

[Claims] At least one first printed wiring board layer that requires electrical connection with the lead of the electronic component to be mounted and at least one second printed wiring board layer that does not require electrical connection between the lead and the lead of the electronic component to be mounted. In the printed wiring board, in which the insertion holes of the second printed wiring board layer are stacked together and the electrical connection is achieved through a land provided in the insertion hole, the insertion hole of the second printed wiring board layer is stacked with the insertion hole of the first printed wiring board layer. A printed wiring board characterized in that the land is formed slightly larger than that of the printed wiring board layer, and the land is provided only on the first printed wiring board layer.