JP2536568B2 - Lead frame - Google Patents

Description

The present invention relates to a hybrid integrated circuit device (hereinafter referred to as a hybrid integrated circuit device).
More specifically, the present invention relates to a lead frame that can be mounted on both sides of a wiring board and that facilitates positioning and mounting of the wiring board.

[Summary of the Invention] According to the present invention, a plurality of frame portions on which a wiring board on which chip components are mounted are mounted are formed on a strip-shaped metal mother board at predetermined intervals along the longitudinal direction of the mother board. In the lead frame, the frame portion has a board mounting hole of a substantially rectangular shape formed in the mother plate, and a plurality of outer leads extend inward from a pair of two opposite peripheral edges of the hole peripheral edge. And a mounting step portion which is formed to be present, and which abuts the peripheral portion of the board in the state where the wiring board is mounted, is formed at the tip portion of the external lead, and the mounting step portion is opposed to the peripheral edge of the board mounting hole. By forming the positioning protrusions inward from the two peripheral edges that form a pair toward the inside of the board mounting holes, a hybrid IC, especially a hybrid IC equipped with double-sided wiring boards, can be transferred by the transfer molding method. Manufactured in The hybrid IC has improved outer shape accuracy, mounting efficiency, economical efficiency, and reliability.

[Prior Art] Conventionally, as a lead frame of this type, Japanese Patent Laid-Open No. 61-2
There is an invention described in Japanese Patent No. 48456. In this conventional example, as shown in FIG. 6, an island portion (die pad) 1 on which an element is mounted, and at least one partial frame arranged around the island portion 1 and electrically independent of a lead frame. 4 and an external lead-out terminal 2 arranged so as to surround the partial frame 4 and the island portion 1,
With the insulating sheet 3, at least the partial frame 4
Is held at a specified position.

Also, as a hybrid IC using a lead frame, there is an invention described in JP-A-60-41249. As shown in FIG. 7, in this conventional example, an insulating layer 6 is provided on a base ribbon (lead frame) 5, a conductor circuit 7 is further provided on the insulating layer 6, and a semiconductor element 8 is mounted thereon. It is configured by applying 9.

[Problems to be Solved by the Invention] However, these conventional examples have the following problems.

That is, since a wiring board (insulating layer) provided with a circuit is arranged and pasted on one side surface of the lead frame in both cases, it is naturally impossible to mount a chip component on the bonding surface of the wiring board. There is a problem that a so-called double-sided mounting board cannot be attached.

Therefore, the hybrid IC using the lead frame has a problem of low mounting efficiency.

The present invention has been made in view of such conventional problems, and in particular, it is used for a package type (SOP type) in which external leads are extended from two opposite side surfaces of a package, and is used as a hybrid. The aim is to obtain a lead frame that not only enhances IC mounting efficiency but also facilitates automated mounting.

[Means for Solving Problems] Therefore, according to the present invention, a plurality of frame portions on which a wiring board on which chip components are mounted are mounted are provided on a strip-shaped metal mother board.
In a lead frame formed at predetermined intervals along the longitudinal direction of the mother plate, the frame portion has a substantially rectangular board mounting hole formed in the mother plate, and faces the peripheral edges of the hole. A plurality of external leads are formed to extend from the pair of two peripheral edges toward the inner side of the hole, and a mounting step portion that abuts the peripheral edge portion of the board in a state in which the wiring board is attached to the tip ends of the external leads. The positioning protrusions are formed so as to protrude toward the inner side of the board mounting hole from the other two pairs of the peripheral edges of the board mounting hole that face each other. I am trying.

[Operation] That is, the wiring board is held at the front and rear two portions by abutting on the mounting step portions of the external leads provided on the pair of two peripheral edges of the board mounting hole in the frame portion. Also,
Both sides of the wiring board form another pair of board mounting holes.
The mounting position is determined by positioning with the positioning projections provided on the peripheral edge. In particular, when the wiring board is mounted on both sides, the chip component mounted on the surface of the board that contacts the mounting step is exposed from the board mounting hole on the back surface of the lead frame. That is, when the wiring board is attached to the lead frame, the chip components on the contact side surface do not prevent the attachment. Therefore, high mounting efficiency can be achieved.

[Embodiment] Hereinafter, details of a lead frame according to the present invention will be described based on an embodiment shown in the drawings.

FIG. 1 is a perspective view showing this embodiment. In the figure, 10
Is a lead frame, and a large number of frame parts 11 are formed in the lead frame 10 at a predetermined interval in the longitudinal direction of a long metal mother plate. This frame portion 11 is provided with a board mounting hole 12 having a substantially square shape which is opened, and a plurality of projecting holes 12 projecting inward from the pair of two peripheral edges of the board mounting hole 12 facing each other. Positioning projections projecting toward the inside of the holes 12 by two from the peripheral edges of the leads 13 to 13 and the other pair of the outer leads 12 of the substrate that face each other.
It is roughly composed of 14 and.

The external lead 13 has a mounting step portion 15 formed at the tip thereof by press working, and the mounting step portion 15 is a hanging plate portion.
It is composed of 16 and a horizontal plate portion 17. The step size of the mounting step 15 is set to be substantially the same as the thickness size of the mounted wiring board 18.

The wiring board 18 has a conductor wiring portion (not shown) and a plurality of contact pads 19 to 19 which are electrically connected to the conductor wiring portion and which are arranged on the peripheral edge of the substrate 18, and further at predetermined positions of the conductor wiring portion. For example, a chip component 20 such as a monolithic IC, a composite transistor, a composite diode, a composite resistor, and a composite capacitor is mounted, connected by wire bonding, and mounted on both sides.

The contact pads 19 are arranged on the peripheral edges of both sides of the wiring board 18, and the pair of front and back contact pads 19, 19 are electrically connected to each other through through holes. Further, on the surface of the contact pad 19 provided on the surface of the wiring board 18 used for attachment to the lead frame 10,
Solder plating is applied and the substrate 18 is connected to the external leads 13
It can be soldered by being placed in an infrared electric furnace while being in contact with the horizontal plate 17. Here, when the chip component 20 is exposed to an infrared electric furnace, it is necessary to set the soldering temperature (the temperature at which the solder is melted) in a short time in order to reduce the thermal damage to the chip component 20.

Further, the mounting step portion 15 of the lead frame 10 is set so as to come into close contact with the wiring board 18 to be mounted, and as described above, the step size and the thickness dimension of the wiring board 18 are substantially the same. The external leads 13 and the wiring board 18 are substantially flush with each other when mounted.

Further, the positioning projections 14 are bent so that the tip ends thereof hang down, and the positioning projections 14 facing each other are bent.
The distance between the tip ends of the wirings is set to be substantially the same as the width dimension of the wiring board 18 mounted on the lead frame 10. Therefore, as shown in FIGS. 2 and 3, the wiring board 18 is
The pair of peripheral edge portions of the frame portion 11 are in contact with the mounting step portion 15, and the pair of peripheral edge portions of the frame portion 11 are in contact with the tip end surface of the positioning projection piece 14, so that the compact pads 19 to 19 have appropriate external leads. Positioning is made so as to abut 13-13.

The wiring board 12 mounted on the lead frame 10 in this way
The mounted chip component 20 can be exposed on the rear surface side of the lead frame 10, and double-sided mounting is allowed without being blocked by mounting.

Further, after the wiring board 18 is fitted into the frame portion 11 and soldered, a pair of molding dies are aligned from the vertical direction of the lead frame 10, and then powdered or tablet-shaped epoxy, silicone, for example. A resin such as is melted by applying temperature and pressure to make it have a low viscosity and is injected into a mold to solidify the resin to form a mold portion 21 (transfer molding method). Next, in the cutting process, the positioning protrusion 14 is cut on the outer periphery of the mold portion 21, and the external lead 13 is cut so as to protrude from the mold portion 21 by a predetermined length, and the hybrid IC is cut off. External leads extending from the two edges of the mold part 21
13 to 13 are bent so as to be suitable for mounting and connection, and a finished hybrid IC is obtained (Fig. 5). When the external lead 13 is bent as described above, the horizontal plate 17 is securely engaged with the wiring board 18.
It is possible to favorably perform the so-called crease bending of the mold portion 21 by the creases of the mold portion 21, and to prevent the soldering damage between the compact pad 19 and the horizontal plate 17 from being damaged.

Although the embodiments have been described above, various other design changes are possible in the present invention. For example, in the above embodiments, two positioning protrusions 14 are provided to face each other. However, the number is not limited to this.

Further, the shape of the positioning projection 14 is not limited to the shape in which the tip is bent so as to hang down as in the above-mentioned embodiment, and the design can be changed to any projection having a positioning function.

Further, in the above embodiment, the wiring board 18 and the horizontal plate
Although 17 and 17 are soldered, the contact pad 19 and the external lead 13 may be wire-bonded by using an adhesive agent, or a conductive adhesive agent may be used.

Further, the step size of the mounting step portion 15 is not limited to the above embodiment, and can be changed as appropriate.

Furthermore, when forming the mounting step 15, it is possible to perform cutting and pressing at the same time, and in particular, pressing can prevent variations between the horizontal plates 17 and allow uniform contact with the wiring board 18 side. Becomes Therefore, good soldering prevents the soldering from being damaged by the mold pressure which the soldering receives from the side during the molding process.

[Effects of the Invention] As is clear from the above description, the lead frame according to the present invention is a package type in which the external leads project in two directions in the hybrid IC, and can be mounted with a small occupied area. The present invention is applied to a lead frame, which is provided with an external lead having mounting step portions at a pair of opposing two peripheral edges of a board mounting hole to be opened, and a positioning protrusion at another pair of peripheral edges. By providing the piece, the positioning of the wiring board is facilitated and the productivity is increased.

Further, since the wiring boards mounted on both sides can be mounted, there is an effect that a hybrid IC with high mounting efficiency can be manufactured, and therefore, the hybrid IC can be made compact.

Further, since the transfer molding method can be applied, it has the effects of enabling automation and improving the outer shape accuracy.

Further, since the wiring board can be directly soldered to the leads, the structural strength is increased, and there are advantages such as prevention of the lead from coming off, and there is an effect of reducing the cost.

Furthermore, since the structure of the lead frame itself is simple, it is easy to manufacture and can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a lead frame according to the present invention, FIG. 2 is a perspective view showing a state in which a wiring board is mounted,
3 is a sectional view of the same, FIG. 4 is a sectional view of the hybrid IC,
FIG. 5 is a perspective view of the hybrid IC, FIG. 6 is a plan view showing a conventional example, and FIG. 7 is a sectional view showing a conventional example. 10 …… Lead frame, 11 …… Frame part, 12 …… Board mounting hole, 13 …… External lead, 14 …… Positioning protrusion, 15
...... Mounting step, 18 ...... Wiring board, 20 ...... Chip parts.

Claims (1)

(57) [Claims] 1. A lead frame comprising a strip-shaped metal mother plate, and a plurality of frame portions on which wiring boards on which chip components are mounted are mounted, formed at predetermined intervals along the longitudinal direction of the mother plate. The frame portion is formed by forming a board mounting hole having a substantially rectangular shape in the mother plate, and extending a plurality of external leads toward the inside of the hole from a pair of two peripheral edges facing each other of the peripheral edge of the hole. And, at the tip of the external lead, in the state where the wiring board is mounted, a mounting step portion that abuts on the peripheral portion of the board is formed,
2. A lead frame, wherein positioning projections are formed so as to protrude toward the inside of the board mounting hole from two other peripheral edges of a pair of opposing ones of the board mounting holes.