JPH05326810A - Lead frame for mounting of electronic circuit device - Google Patents

Abstract

PURPOSE:To prevent the generation of migration effect by die bonding part, to suppress an adverse effect inflicting on wire bondability by the out-gas generated from a bonding agent, and to improve the appearance by a method wherein an electronic circuit element mounting wiring substrate and the substrate supporting lead of a lead frame are connected without specially using a bonding agent and die-bonding paste. CONSTITUTION:Through holes 6a are made in a semiconductor element mounting wiring substrate 6, and a substrate supporting lead 8, which supports the semiconductor element mounting wiring substrate 6, is formed on a lead frame member 11. After the tip of the inner edge part 8a of the substrate supporting lead 8 has been bent upward, the upwardly bent part of the inner edge part 8a is passed through the through hole 6a, and the semiconductor element mounting wiring substrate 6 is supported by the substrate supporting lead 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit in which a predetermined number of electronic circuit elements are mounted on a predetermined number of substrate supporting leads provided on a lead frame member having no die pad for mounting electronic circuit elements. The present invention relates to an electronic circuit element mounting lead frame configured by mounting an element mounting wiring board.

[0002]

2. Description of the Related Art Conventionally, a lead frame used as a member for assembling a semiconductor device has a plane shape as shown in FIG. 7, for example. This lead frame is
For example, a die pad 1 for mounting a semiconductor element
And an inner lead 2 for connecting with a semiconductor element arranged around the inner lead 2, and an outer lead 3 continuous with the inner lead 2 for connecting with an external circuit.

Such a lead frame is usually made of a metal plate such as Kovar, 42 alloy, copper alloy, etc., which is excellent in conductivity and has high strength, by a photo-etching method or a stamping method. It is manufactured by processing into a shape having the lead 2 and the outer lead 3.

When assembling a semiconductor device using this lead frame, as shown in FIG. 8, a semiconductor element 4 (hereinafter also simply referred to as "element") is attached to the die pad 1 of the lead frame, and at the same time, a bonding pad for the element 4 is formed. A semiconductor device is assembled by electrically connecting (not shown) and the inner lead 2 with a wire 5 made of gold or the like. Therefore, usually, the bonding position of the inner lead 2 is plated with a noble metal such as gold or silver so that wire bonding can be reliably performed.

By the way, downsizing and high performance of electronic equipment,
Furthermore, various monolithic ICs have been developed for lower cost. As a representative example of such a monolithic IC, an LSI adopting a Bi-CMOS process has been particularly attracting attention in recent years. This Bi-CMOS process technology has excellent bipolar high speed / driving capability and CMO.
This process technology has attractive features suitable for A-DLSI (analog-digital mixed LSI) that combines low power consumption of S. However, it is extremely difficult to fabricate individually manufactured semiconductor elements as a monolithic IC by a process composite technology.

In the case of monolithic IC, I
Not only will it take a lot of time and money to develop C, but the problem that the cost of the process will increase due to compounding will be greatly highlighted. Furthermore, there is also a combination of semiconductor elements that are considered to be difficult to make into a monolithic IC.

A hybrid IC technique has been conventionally used as a technique for replacing such a monolithic IC which is difficult. This hybrid IC technology uses monolithic I
It is possible to overcome the region and manufacturing conditions that cannot be covered by C-type. However, hybrid IC technology is particularly costly when dealing with small integrated ICs. Therefore, it is not suitable to use the hybrid IC technology in electronic devices having a small number of parts. On the other hand, in electronic devices, a differentiation strategy has been carried out, and for that purpose, there is a strong demand for a technology capable of realizing light, thin, short and small electronic devices.

From such a background, by mounting a plurality of semiconductor elements in an existing IC package, it is possible to cover an area which is difficult to realize by the composite monolithic / hybrid IC technology, that is, MCP (Muli Chip Packag).
e) A new integration technology called technology is being developed.

[0009]

Various methods have been developed for this MCP technology, and one of them has been developed as shown in FIGS. 9 (a) and 9 (b). There is a method in which 9 semiconductor elements 4 are mounted on the wiring board 6 and the wiring board 6 is bonded onto the solid die pad 1 of the lead frame member 11 corresponding to the above-mentioned conventional lead frame. .. As another method of the MCP technique, as shown in FIGS. 10A and 10B, the wiring board 6 on which the semiconductor element 4 similar to that shown in FIG. 9 is mounted serves as a board mounting frame for the lead frame member 11. There is also a die pad having such a shape, that is, a method of bonding the die pad on the substrate supporting lead 8.

However, in the MCPs shown in FIGS. 9 and 10, respectively, the adhesive or the die bonding paste 7 is used to connect the wiring board 6 and the lead frame member 11. In that case, the adhesive and the die bonding paste are used. 7 may protrude from the wiring substrate 6 onto the die pad 1 of the lead frame member 11 or the substrate supporting leads 8. The protrusion α of the adhesive and the die bonding paste 7 causes a problem that the appearance is impaired.

In particular, when a die bonding paste is used, the die bonding paste is preferably a resin such as epoxy or polyimide mixed with flake-like Ag for imparting electric conductivity and thermal conductivity. Used. When the amount of protrusion α of the die bonding paste is large, Ag mixed in the paste may short-circuit with the inner leads 2 of the lead frame member 11.

As another problem, when a voltage is applied between the electrodes, migration due to factors such as moisture and specific ions is caused, or when a solvent-containing adhesive is used as the adhesive, the adhesive is squeezed out. The larger the amount of α, the more the amount of outgas generated during curing increases, which may increase the degree of adverse effects on wire bondability.

The present invention has been made in view of the above problems, and an object thereof is to provide a wiring board for mounting electronic circuit elements and a board of a lead frame member without using an adhesive or a die bonding paste. By making it possible to connect to the supporting leads, it is possible to prevent the migration effect of the die bonding paste, suppress the adverse effect on wire bondability due to outgas generated from the adhesive, and further improve the appearance. It is to provide a lead frame for a device.

[0014]

In order to solve the above-mentioned problems, the invention of claim 1 mounts a predetermined number of electronic circuit elements on a substrate supporting lead provided on a lead frame member having no die pad. In a lead frame for mounting an electronic circuit element, which is configured by connecting the wiring board for mounting an electronic circuit element, a through hole is formed at a predetermined position of the wiring board for mounting an electronic circuit element. The wiring board for mounting the electronic circuit element is connected to the lead frame member by passing the board supporting lead through.

Further, the invention of claim 2 is characterized in that the tip of the substrate supporting lead penetrating the through hole is further caulked. According to a third aspect of the present invention, in the connection state of the electronic circuit element mounting wiring board and the board supporting lead on the surface of the electronic circuit element mounting wiring board opposite to the mounting surface of the electronic circuit element. A recess is formed so that the surface on the opposite side and the surface of the substrate supporting lead are flush with each other.

[0016]

In the electronic circuit element mounting lead frame of the present invention thus constructed, the electronic circuit element mounting is performed by passing the substrate supporting leads of the lead frame member through the through holes of the electronic circuit element mounting wiring board. Since the wiring board for use is supported by the lead frame member, the board supporting lead and the electronic circuit element mounting wiring board can be connected without using an adhesive or a bonding paste. Therefore, the adhesive or the bonding paste does not squeeze out when the lead frame member is mounted on the wiring board for mounting electronic circuit elements, and there is no risk of adverse effects on migration or wire bondability. Moreover, the appearance of the lead frame becomes extremely good because the adhesive and the bonding paste do not stick out.

Further, in the lead frame of the present invention, since almost no adhesive is used or no adhesive is used at all, heat dissipation is improved and reliability can be further improved. In that case, according to the lead frame of the present invention, since the die pad for mounting the electronic circuit element is not provided, the heat dissipation property is further improved.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view similar to FIG. 10A, partially showing an embodiment of an electronic circuit element mounting lead frame according to the present invention with an electronic circuit element mounted, and FIG.
FIG. 3 is a partially enlarged plan view of FIG. 3, and FIG. 3 is a sectional view taken along line III-III in FIG. In addition, the above-mentioned FIG.
The same components as those shown in FIG. 10 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, a semiconductor element mounting lead frame 10 will be described as an electronic circuit element mounting lead frame. As shown in FIGS. 1 and 2,
The semiconductor element mounting lead frame 10 is mounted on and supported by a lead frame member 11 corresponding to a conventional lead frame and the lead frame member 11.
And a wiring board 6 for mounting a semiconductor element having a rectangular shape.

The lead frame member 11 has a predetermined number of inner leads 2 as in the conventional lead frame shown in FIG.
And a die padless lead frame member that has outer leads (not shown) continuous with these inner leads 2 but does not have the die pad 1. The lead frame member 11 is formed of a metal such as a copper alloy, 42 alloy, or Kovar as in the conventional lead frame. Further, the lead frame member 11 is
Four board supporting leads 8 for supporting the semiconductor element mounting wiring board 6 are provided at the four corners thereof, as described later. As shown in FIG. 3, the inner end portions 8a of the substrate supporting leads 8 are respectively depressed downward.

The semiconductor element mounting wiring board 6 is erected and supported between the inner ends 8a of the four board supporting leads 8. In that case, each substrate supporting lead 8
After the tip of the inner end portion 8a of the substrate is bent upward and the upper bent portion of the inner end portion 8a is passed through the through hole 6a, the semiconductor element mounting wiring substrate 6 is supported by the substrate supporting leads 8. There is. In this way, the semiconductor element mounting wiring board 6 is connected to and supported by the lead frame member 11 without using a conventional adhesive or bonding paste.

As with the conventional wiring board, a predetermined number (five in FIG. 1) of semiconductor elements 4 can be mounted on the semiconductor element mounting wiring board 6 in this embodiment, and A predetermined number of wiring leads 6b are provided to enable electrical connection between the semiconductor elements 4 and between the inner leads 2.

As described above, in the semiconductor element mounting lead frame 10 of this embodiment, the substrate supporting leads 8 and the semiconductor element mounting wiring board 6 can be connected to each other without using any adhesive or bonding paste. You can
Therefore, when the lead frame member is mounted on the semiconductor element mounting wiring board 6, the adhesive or the bonding paste does not squeeze out, and there is no risk of adverse effects on migration or wire bondability. Moreover, the appearance of the lead frame becomes extremely good because the adhesive and the bonding paste do not stick out.

Further, since the lead frame 10 of this embodiment does not have a die pad for mounting the semiconductor element 4, the heat dissipation is good, but an adhesive is further used. Since it does not exist, heat dissipation is further improved and reliability is increased. However, in the present invention, an adhesive may be used to connect the substrate supporting lead 8 and the semiconductor element mounting wiring substrate 6. In this case, since the adhesive is used only at the connecting portion between the substrate supporting lead 8 and the semiconductor element mounting wiring substrate 6, there is no problem with respect to heat dissipation. Moreover, since a small amount of the adhesive is sufficient, the adhesive does not overflow.

Further, as shown in FIG. 3B, the tip 8b of the substrate supporting lead 8 penetrating the through hole 6a of the semiconductor element mounting wiring board 6 is caulked to support the semiconductor element mounting wiring board 6 on the substrate. By firmly connecting to the lead 8,
The reliability of the connection can be improved.

FIG. 5 shows another embodiment of the present invention, which is shown in FIG.
It is a sectional view similar to FIG. As shown in FIG. 5, in this embodiment, on the surface of the semiconductor element mounting wiring board 6 opposite to the surface on which the semiconductor element 4 is mounted (the lower surface in the figure), the inner end portions of the substrate supporting leads 8 at the four corners thereof. The recesses 6c having substantially the same shape as the above are formed up to the through holes 6a along the extending direction of the corresponding substrate supporting leads 8 (the recesses 6c are shown in FIG. Shown in detail by the broken line).

The depth of these recesses 6c from the lower surface of the semiconductor element mounting wiring substrate 6 is set to be equal to the thickness of the substrate supporting leads 8 of the lead frame member 11. These recesses 6c can be formed at the same time as the formation of the wiring circuit by using the double-sided etching as the single-sided etching of the wiring board which is performed when the wiring circuit is formed on one surface of the substrate. Therefore, the lead frame member 11 of this embodiment can be formed without adding a special process.

Then, when the substrate supporting leads 8 and the semiconductor element mounting wiring substrate 6 are connected to each other, the other portion of the inner end portion 8a other than the upwardly bent portion is fitted into the recess 6c.
The semiconductor element mounting wiring board 6 is supported by the board supporting leads 8. Therefore, since the inner end portion 8a is fitted in the concave portion 6c, the semiconductor element mounting wiring board 6 does not move vertically and horizontally in FIG. 1A. Further, when the inner end portion 8a of the substrate supporting lead 8 is fitted in the recess 6c, the lower surface of the semiconductor element mounting wiring substrate 6 is flush with the lower surface of the substrate supporting lead 8 as shown in FIG. ..

In this way, the semiconductor element mounting wiring board 6
6 (a) and 6 (b) are used to heat the inner lead 2 during wire bonding to the inner lead 2 by making the lower surface of the inner surface flush with the lower surface of the substrate supporting lead 8. It is possible to use the conventional heat piece 12 as shown in FIG. That is, in the conventional heating piece 12, the inner lead 2 and the substrate supporting lead 8 are formed by depressing the inner end portions of the substrate supporting lead 8.
Since there is a step between and, the surface of the heat piece 12 is provided with steps a and b as much as the step, and
The surface c on which the inner end 8a of the substrate supporting lead 8 is placed is a flat surface. Therefore, since the lower surface of the semiconductor element mounting wiring substrate 6 and the lower surface of the substrate supporting lead 8 are on the same plane, the surface c is not processed at the time of wire bonding to the inner lead in the lead frame of this embodiment. The heat piece 12 can be used without being flat.

Further, since the structure is such that the substrate supporting leads 8 are fitted in the recesses 6c formed in the semiconductor element mounting wiring board 6, the connecting portions between the substrate supporting leads 8 and the semiconductor element mounting wiring board 6 are connected. Since the thickness is thin, the semiconductor device can be thinner than before. In addition, in the above-mentioned embodiment, the case where the semiconductor element is mounted is explained, but the present invention can be applied to the case where another electronic circuit element is mounted.

[0031]

As is apparent from the above description, according to the lead frame for an electronic circuit element of the present invention, there is no fear of adverse effects on migration and wire bondability, and the appearance is improved. Further, since almost no adhesive is used or no adhesive is used at all, heat dissipation is improved and reliability can be further improved. In that case, according to the lead frame of the present invention, since the die pad for mounting the electronic circuit element is not provided, the heat dissipation property is further improved.

Further, since the board supporting leads are fitted in the concave portions of the electronic circuit element mounting wiring board,
The electronic circuit device can be made even thinner. Furthermore, according to the present invention, since wire bonding can be performed with a conventional heating piece without preparing a special heating piece, an electronic circuit device can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a plan view partially showing an embodiment of an electronic circuit element mounting lead frame according to the present invention with an electronic circuit element mounted.

FIG. 2 is a partially enlarged plan view of FIG.

FIG. 3 shows a cross section taken along line III-III in FIG.
(A) is a cross-sectional view showing a state in which a substrate supporting lead is passed through a through hole of a semiconductor element mounting wiring board, and (b) shows a tip of the substrate supporting lead penetrating the through hole of a semiconductor element mounting wiring board. It is sectional drawing which shows the crimped state.

FIG. 4 is a plan view schematically showing a semiconductor element mounting wiring board.

FIG. 5 is a sectional view similar to FIG. 3B, showing another embodiment of the present invention.

FIG. 6 shows a conventional heating piece, (a) is a plan view thereof, and (b) is a sectional view taken along line VIB-VIB in (a).

FIG. 7 is a plan view of a conventional general lead frame.

FIG. 8 is a diagram schematically showing a main part of a semiconductor device manufactured using this conventional lead frame.

FIG. 9 illustrates problems in the conventional MCP,
(A) is its schematic plan view, (b) is IXB in (a)
FIG. 6 is a sectional view taken along the line IXB.

10A and 10B illustrate problems in another conventional MCP, in which FIG. 10A is a schematic plan view thereof, and FIG.
It is a sectional view taken along line XB-XB.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Die pad, 2 ... Inner lead, 3 ... Outer lead, 4 ... Semiconductor element, 5 ... Wire, 6 ... Semiconductor element mounting wiring board, 6a ... Through hole, 6b ... Wiring lead, 6c
... Recesses, 7 ... Adhesive or bonding paste, 8 ...
Substrate supporting leads, 8a ... Inner ends of the substrate supporting leads,
8b ... Tip of substrate supporting lead, 10 ... Lead frame, 11 ... Lead frame member, 12 ... Heat piece

Claims (3)

[Claims] 1. An electronic circuit element configured by connecting an electronic circuit element mounting wiring board on which a predetermined number of electronic circuit elements are mounted to a substrate supporting lead provided on a lead frame member having no die pad. In the mounting lead frame, a through hole is formed in a predetermined position of the electronic circuit element mounting wiring board, and the electronic circuit element mounting wiring board is formed by passing the board supporting lead through the through hole. A lead frame for mounting an electronic circuit element, which is connected to the lead frame member. 2. The lead frame for mounting an electronic circuit element according to claim 1, further comprising caulking a tip of the substrate supporting lead penetrating the through hole. 3. The electronic circuit element mounting wiring board is provided on a surface of the electronic circuit element mounting wiring board opposite to the electronic circuit element mounting surface, in the state where the electronic circuit element mounting wiring board and the substrate supporting lead are connected to each other. 3. The lead frame for mounting an electronic circuit element according to claim 1, wherein a recess is formed such that the surface of the substrate and the surface of the substrate supporting lead are flush with each other.