JPH03268475A - Printed wiring board lead frame and printed wiring board mounting method - Google Patents

Abstract

PURPOSE:To improve an assembly accuracy and workability to insert a lead pin to a printed wiring board by providing a second cut bending section, which is cut and bent in a slanting manner to the surface of a second band body and a band-shaped end whose width is narrower than the width of the second band body. CONSTITUTION:Printed wiring boards 9 and 10 are successively fitted into respective second band bodies A, B, and C by way of through holes 9a and 10a, corresponding to respective second band bodies A, B, and C. They are positioned and maintained hierarchically at each first cut bending section 5 belonging thereto and at a position opposite to a second cut bending end 6 whose width is narrower than the width of the second band body A, B, and C. Each cut bending section 2 is accordingly deformed as the printed wiring boards 9 and 10 are inserted, which does not prevent their insertion. They are returned to their original positions when the printed wiring boards are located at an opposite position having a span equivalent to the thickness. This construction makes it possible to keep each mutual span between the printed wiring board and the right angle between the printed wiring boards and lead pins accurately, thereby improving the assembly accuracy.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a lead frame used when configuring printed wiring boards in a hierarchical manner to improve packaging density, and a printed wiring board mounting method.

[Conventional technology]

Currently, various methods as described below are being used for high-density mounting of printed wiring boards. For example, methods for mounting components include single-sided, single-sided surface mounting, and ASIC (LSI for specific applications).
There is. Further, as methods related to printed wiring boards, there are multilayer printed wiring boards and multilayer printed wiring boards. One method of multi-layered printed wiring boards is to use connectors to mechanically and electrically connect the upper and lower printed wiring boards, for example. Another method is to use a lead frame, that is, a clip-type lead frame, which holds the upper and lower printed wiring boards by sandwiching them at their edges and provides electrical continuity.

[Problem B to be Solved by the Invention] In the method of using connectors to construct a multilayer printed wiring board, soldering work is required to connect the connector and each printed wiring board through the through holes. This work is particularly difficult in very confined spaces, requires skill, and has low reliability. Another problem is that it is very difficult to accurately obtain the perpendicularity between the connector and the printed wiring board. Note that the perpendicularity between the connector and the printed wiring board is a very important factor that determines the success or failure of the two-layer structure. In the method of using a clip-type lead frame to construct a multilayer printed wiring board, the electrical conduction points are limited to the edges of the printed wiring board, which limits circuit design and requires relatively small printed wiring. It tends to apply only to boards. Naturally, a small printed wiring board must be manufactured by combining the boards into a large printed wiring board, inspecting the whole board, dividing it, and then mounting it. The object of the present invention is to provide a lead frame for a hierarchical printed wiring board, which solves the problems of the conventional technology, and improves assembly accuracy and workability in inserting lead pins into the printed wiring board, and a printed wiring board. The object of the present invention is to provide a board mounting method.

[Means to solve the problem]

In order to solve this problem, the lead frame for a hierarchical printed wiring board according to the present invention includes a first strip and a plurality of second strips extending in one direction at right angles to the first strip from each location in the longitudinal direction of the first strip. A band body is integrally formed from a metal plate, and this second band body includes, in order from the root thereof, a notch portion; and a first cut portion cut and bent at right angles to the surface of the second band body. a second bent part which has an end facing the first bent part at a certain distance and is cut and bent in a shape that is inclined with respect to the second band surface; a stepped part; and a band-shaped tip portion having a width narrower than the width of the second band member at the boundary. Further, in the printed board mounting method according to the present invention, a first strip and a plurality of second strips extending in one direction at right angles from each location in the longitudinal direction of the first strip are integrated from a metal plate. The second band includes, in order from the root thereof, a notch portion; a first cut portion cut and bent at right angles to the surface of the second band; and a portion that is constant with the first cut portion. a second bent portion having opposite end portions separated by a distance and cut and bent in a shape that is inclined with respect to the second band surface; narrower than the width of the second band with the step-like stepped portion as the boundary; A first printed wiring board is sequentially inserted into each of the second strips through through holes corresponding to each of the second strips using a lead frame having a wide strip-shaped tip; The second printed wiring board is positioned and held in a hierarchical manner at each of the opposing points belonging to the above, and then a second printed wiring board is fitted into each of the tips through the through holes corresponding to the respective tips of the stepped portions belonging to this. Finally, each of the second strips is cut and separated from the first strip at its notch, and the first printed wiring board is mounted on the second printed wiring board. Each item will be in a broken state.

[Effect]

The printed wiring board is sequentially fitted into each of the second strips through through-holes corresponding to the second strips, and the ends of the first and second bent portions thereof are opposed to each other. It is positioned and held in a hierarchical manner at certain points. Note that each of the second bent portions deforms as the printed wiring board is inserted and does not interfere with the insertion, and returns to its original position when the printed wiring board is located at an opposing position with an interval equal to the thickness of the printed wiring board. Together with the cut portion, the printed wiring board is positioned and held. Next, another printed wiring board is inserted into each of the ends of each second band through the through holes corresponding to the ends thereof, and is positioned and held by the corresponding step portion. This completes the hierarchical insertion of the printed wiring board into the second band. Finally, each of the second strips is separated from the first strip by cutting at its notch, thereby forming a lead bin inserted into the hierarchical printed wiring board.

【Example】

Examples of the lead frame for printed wiring boards according to the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of an embodiment according to the first invention. 1st
In the figure, a lead frame 1 is a member in which a frame 2 as a first band and a lead bin 3 as a second band are integrally punched out of a metal plate. Feed holes 2a of a fixed pitch are drilled in the frame 2, and the lead frame 1 is manufactured using these holes 2a.
storage. used - to be used. The lead bin 3 is a portion extending from a fixed pitch point of the frame 2 at right angles thereto. The lead bin 3 has a V-shaped notch 4 on both sides, a bent part 5 on both sides, a bent part 6 in the center, and a stepped part 7 in order from the base of the lead bin 3 to the frame 2. , and a tip portion 8 whose width becomes narrower with this stepped portion 7 as a boundary. A in FIG. 1 is punched out,
The lead bin is shown with cuts corresponding to the cut portions 5 and 6. Same <B, C, the cut portion 5 and the cut portion 6 are at right angles or inclined to the front side,
The lead bins are shown in their respective folded positions on the opposite side. Therefore, in the lead frame 1, lead bins in states B and C are successively arranged side by side. The reason why the bending directions of each of the cut portions 5.6 are alternated is to balance the force when holding the printed wiring board in a subsequent process. Next, a method for mounting a printed wiring board according to the present invention will be described. FIG. 2 is a side sectional view of the two-layer printed wiring board in a state where the beams and pins are inserted, and FIG. 3 is another side sectional view of FIG. 2 viewed from the right side. In FIG. 2, the printed wiring board 9 is inserted upward from the tip end 8 side of the lead bin 3 through the through hole 9a, and moves up while pushing and deforming the bent part 6, and bends the bent part 5 at a right angle. It is held in position by being sandwiched between the curved surface and the tip of the bent portion 6 which returns to its original state due to elasticity. The printed wiring board 9 and the lead bin 3 form a right angle. Next, another printed wiring board 10 has through holes 10a.
It is inserted into the tip part 8 of the lead bin 3 through the step part 7.
is positioned. Printed wiring board worker 0 and lead bin 3
There is a right angle. In this case, each printed wiring board 9.10 forms a two-layer structure. Although not shown in the drawings, by providing a plurality of sets of each of the bent portions 5.degree.6 in series in the direction of the lead bin, a structure of three or more layers of the printed wiring board can be obtained. Finally, in FIGS. 2 and 3, the frame 2 indicated by the two-dot chain line is cut and separated from each lead bin 3 at the notch 4, and each lead bin 3 is inserted into the two-layer printed wiring. The board is completed. Incidentally, the above-mentioned insertion and cutting of each lead frame 3 onto the printed wiring board are all performed by an automatic insertion machine.

【Effect of the invention】

According to this invention, there are the following superior effects compared to the conventional technology. (1) The distance between the printed wiring boards is
The position of the bent part is accurate because it is determined by the position of the one step part. Further, the perpendicularity between the printed wiring board and the lead bin is determined by each first cut portion of the second band. It is accurate because it is determined by the squareness of the step. In this way, assembly precision can be improved. (2) Since a plurality of second strips are grouped together by a common first strip, each second strip is inserted into the printed wiring board at once, and then the first The strip is cut into 9 parts. Therefore, assembly work is easy to automate;
It's very easy and takes a short time. (3) The accuracy of the lead pin itself is high because the second band, which is to become a lead bin, is held together by a common first band before being inserted into the printed wiring board. It has good processing efficiency and is stored in the form of being wound onto a reel, so it is very convenient in terms of handling and storage. (4) Since the lead bin is inserted into the printed wiring board through a through hole, there are no restrictions on the circuit configuration and it can be widely applied to general printed wiring boards.

[Brief explanation of drawings]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a side sectional view of the two-layer printed wiring board with the lead bin inserted, and FIG. 3 is another side sectional view thereof. Code explanation 1: Lead frame, 2: Frame, 2a: Feed hole, 3: Lead bin, 4: Notch, 5
．． 6: Bent part, 7: Step part, 8: Tip part, 9.10 Niblint wiring board, 9a, 10a Varnish through hole. Figure 2 Figure 3 Figure 1

Claims (1)

[Claims] 1) A first strip and a plurality of second strips extending in one direction at right angles from each location in the longitudinal direction of the first strip are integrally formed from a metal plate, This second band includes, in order from the root thereof, a notch; a first cut portion cut and bent at right angles to the surface of the second band; a second bent part having opposite ends and cut and bent in a shape inclined with respect to the second band surface; having a width narrower than the width of the second band with the step-like stepped part as a boundary; A lead frame for a printed wiring board, characterized by having a band-shaped tip; and; 2) A first strip and a plurality of second strips extending in one direction at right angles from each location in the longitudinal direction of the first strip are integrally formed from a metal plate, and the second strips are , in order from the root to the notch part; a first cut part cut and bent at right angles to the surface of the second band; and an end part facing the first cut part at a certain distance. a second bent portion that is cut and bent in a shape that is inclined with respect to the second band surface; a band-shaped tip portion that has a width narrower than the width of the second band with the step-like stepped portion as a boundary; A first printed wiring board is sequentially inserted into each of the second strips through through-holes corresponding to the second strips, using a lead frame having Next, a second printed wiring board is inserted into each of the tips through through holes corresponding to the tips and is positioned and held at the stepped portions belonging thereto. The second band body is
A printed wiring board mounting method characterized in that the first printed wiring board is cut and separated from the first band at the notch portion, and the first printed wiring board is mounted on the second printed wiring board.