JPH0870080A - Composite lead frame - Google Patents

Abstract

PURPOSE: To reduce the deformation of a lead frame which is caused by temperature change, by forming the linkage part of a lead frame so as to be able to absorb the stress applied to the lead frame, when a printed wiring board expands or contracts. CONSTITUTION: The linkage part 26 of a lead frame 20 consists of the following; a lead part side protruding segment 26a protruding from a lead part 21 to the outside, parallel with outer leads 23, 23,..., a lead frame side protruding segment 26b protruding from the lead frame 20 to the inside, in the outside of the lead part 21 and in the sifted position, parallel with the outer leads 23, 23,..., and an absorption segment 26c which is rectangular to both of the protruding segments 26a and 26b and linked with the tips of them. In the semiconductor element mounting process and the wire bonding process, the lead frame 20 is set in an atmosphere at about 220 deg.C, and the stress applied to the lead frame 20 is absorbed by the absorption segment 26c stretching in the direction rectangular to the expansion and contraction direction of a printed wiring board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite lead frame having a printed wiring board and a lead frame forming a semiconductor package.

[0002]

2. Description of the Related Art A semiconductor element is mounted on a lead frame,
In a semiconductor package in which these are resin-molded and sealed, the semiconductor package may be warped and deformed after the resin molding due to a difference in thermal expansion coefficient between the lead frame and the sealing resin. As means for reducing this warp deformation, for example, Japanese Patent Laid-Open No. 3-124054 discloses a device in which a slit is provided around the lead portion of the lead frame. Such means is also applied to the lead frame of the composite lead frame in which the printed wiring board is connected and fixed to the lead frame.

As this type of composite lead frame, there is a simplified structure shown in FIG. In the figure, 10 is a printed wiring board, which is made of a non-metallic material such as an organic material or a ceramic, and is used to mount a semiconductor element on the mounting portion 11. When the semiconductor element is mounted on the mounting portion 11, each terminal portion corresponds to the mounting portion. Conductive portion 12 formed so as to extend outward
Is formed.

Reference numeral 20 denotes a lead frame, which is made of a metal material, and is provided with a plurality of printed wiring boards 10, ... In parallel, and inner leads 22 for connecting and fixing the outer ends of the respective conductive portions 12, 12 ,. , 22, and outer leads 23, 23, which serve as terminals of the semiconductor package, and a printed wiring board 10, while supporting the lead portion 21 via a connecting portion 26 provided around the lead portion 21. It is formed by having a frame portion 25 extending in the juxtaposed direction.

The connecting portion 26 is provided in the slit 27 provided around the lead portion 21 and the slit 27.
The width of the slit 27 and the width of the connecting portion 26 are about 0.6 mm, for example, as shown in FIG. 28 is a positioning hole for positioning in the manufacturing process.

In the manufacturing process of the semiconductor package, first, the inner ends of the inner leads 22, 22, ... Of the lead frame 20 and the outer ends of the conductive parts 12, 12, ... Of the printed wiring board 10 ,. Then, the semiconductor element is mounted on the mounting portion 11 of the printed wiring board 10, ... Using a resin die bonding agent or the like.
(Semiconductor element mounting process) Next, each terminal portion of the semiconductor element and each inner end of each conductive portion 12, 12, ... Are connected by a thin metal wire such as gold (wire bonding step), and then inner leads The area including most of the inner side of 22,22, ... Is inserted into the resin molding die to perform resin molding (resin molding process), and the lead portions 21, 21 ... The lead portions 21, 21 ... Protruding from the molded portion (hereinafter referred to as the package) are appropriately bent (cutting and bending steps). In the lead frame 20 shown in FIG. 11, three semiconductor packages are manufactured.

[0007]

By the way, as the lead frame described above, one made of a copper alloy is being widely used in order to improve the thermal conductivity and reduce the cost, and the plate thickness thereof is about 0.1 mm. . Further, in the semiconductor element mounting process and the wire bonding process, a temperature atmosphere of about 200 ° C. is used. Then, these steps are sequentially carried using the positioning holes, but if the warp of the lead frame becomes large, smooth carrying becomes difficult.

It has been confirmed by the applicant of the present application that the lead frame has a plate thickness of 0.12 mm and a longitudinal length of 160 m.
When it was placed in an atmosphere at a temperature of 220 ° C. with m and a length in the width direction of 61 mm, warpage of about 2 to 3 mm occurred. This is due to the difference in thermal expansion coefficient between the lead frame and the printed wiring board. When such warpage occurs,
The steps such as using a warp correction jig during the transportation in the steps described above become complicated.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a composite lead frame capable of further reducing the deformation of the lead frame due to temperature change.

[0010]

In order to solve such a problem, the composite lead frame according to claim 1 is arranged so that, when a semiconductor element is mounted at a predetermined position, the composite lead frame extends outward corresponding to each terminal portion thereof. A lead consisting of a printed wiring board on which a conductive portion is formed, an inner lead for arranging a plurality of printed wiring boards in parallel and connecting and fixing the outer ends of the respective conductive portions, and an outer lead serving as a terminal of a semiconductor package. And a lead frame supporting a lead portion through a connecting portion provided around the lead portion and a frame portion extending in a direction in which a printed wiring board is provided side by side, and a connecting portion of the lead frame. Is formed so that the stress on the lead frame can be absorbed when the printed wiring board expands or contracts.

According to a second aspect of the present invention, there is provided a composite lead frame, wherein the connecting portion of the lead frame according to the first aspect is provided with a connecting piece positioned in a direction of expansion or contraction of the printed wiring board and a stress absorption longer than its lateral width. The slit is formed by a lead portion and a slit forming piece formed on at least one of the lead frames outside the lead portion.

According to a third aspect of the present invention, there is provided a lead frame-side protruding piece formed by shifting the connecting portions of the lead frame according to the first aspect from each other, and a lead frame-side protruding piece outside the lead portion. , And an absorbing piece in which the tip end portions of both projecting pieces are arranged so as to extend in a direction substantially orthogonal to the expansion or contraction direction of the printed wiring board.

According to a fourth aspect of the present invention, in the composite lead frame, at least one of the lead portion side protruding piece and the lead frame side protruding piece is defined by a lateral width of the lead portion side protruding piece and the lead frame side protruding piece. A long stress absorbing slit is continuously provided to a slit forming piece formed on at least one of the lead portion and the lead frame outside the lead portion.

The composite lead frame according to a fifth aspect of the present invention is configured such that a bent portion bent in a U-shape is formed on a part of the absorbent piece according to the third aspect.

Further, in the composite lead frame according to claim 6, the frame portion according to claims 1 to 5 has a structure in which the direction in which the printed wiring boards are arranged in parallel has a high rigidity structure as compared with the lead portion.

[0016]

According to the structure of claim 1, when the printed wiring board expands or contracts, the stress to the lead frame is reduced.
Since it is absorbed by the connecting portion, deformation of the lead frame due to temperature change can be reduced.

According to the second aspect of the invention, the slit forming piece of the connecting portion absorbs the stress to the lead frame when the printed wiring board expands or contracts.

According to the third aspect of the invention, the absorbing piece of the connecting portion absorbs the stress to the lead frame when the printed wiring board expands or contracts.

According to the structure of claim 4, the slit forming piece and the absorbing piece of the connecting portion absorb the stress to the lead frame when the printed wiring board expands or contracts.

According to the fifth aspect of the invention, the bending portion of the connecting portion absorbs the stress on the lead frame when the printed wiring board expands or contracts.

According to the sixth aspect of the invention, in addition to the actions of the first to fifth aspects, the frame portion is less likely to be deformed, and the deformation of the lead frame due to temperature change can be further reduced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. The composite lead frame of the present invention has a printed wiring board and a lead frame as main constituent members, and in particular, the lead frame is different from the conventional example. It should be noted that constituent members having substantially the same basic functions as those described in the conventional example are denoted by the same reference numerals as those in the drawings showing the conventional example.

The printed wiring board 10 is made of a non-metallic material such as an organic material or a ceramic, as in the conventional example, and a mounting portion 11 on which a semiconductor element is mounted, and when the semiconductor element is mounted on the mounting portion 11. The conductive portion 12 is formed to extend outward corresponding to each terminal portion. Note that the conductive portion 12 in each drawing is illustrated in a simplified manner.
The printed wiring board 10 has a laminated structure such that the conductive portions 12 are multi-layered.

The lead frame 20 is made of a metal material such as 42 alloy (iron / nickel alloy), preferably copper alloy, and a plurality of printed wiring boards 10, ... A lead portion 21 composed of inner leads 22, 22, for connecting and fixing the outer end portions of 12, ... and outer leads 23, 23, ... serving as terminals of a semiconductor package, and a lead portion 21 provided around the lead portion 21. While supporting through the part 26,
Frame portion 25 extending in the direction in which the printed wiring boards 10 are arranged in parallel.
It is the same as the conventional one. 27 is a slit provided around the lead portion 21, and 28 is a positioning hole for positioning in the manufacturing process. In addition,
In FIG. 1, only one semiconductor package is shown.

Outer end portions of the inner leads 22, 22, ... Are formed parallel to each other in the vertical or horizontal direction at regular intervals, and the inner lead portion near the center is linear with the outer end portion. However, it is inclined toward the outside. Outer lead 23,23,
Are formed in parallel in the vertical or horizontal direction at regular intervals corresponding to the outer ends of the inner leads 22, 22 ,.

Next, a lead frame which is an essential part of the present invention
The connecting portion 26 of 20 will be described. As shown in FIG. 2, the connecting portion 26 extends from the lead portion 21 to the outer leads 23, 23, ...
And a lead portion side protruding piece 26a that protrudes outward in parallel to the lead portion 21 and a lead portion 21a that protrudes inward from the lead frame 20 outside the lead portion 21 in a position parallel to the outer leads 23, 23 ,. Frame side protruding piece 26b and both protruding pieces 26
It is composed of an absorbing piece 26c which is connected to the tips of a and 26b in a direction orthogonal to them. In this embodiment, the connecting portion 26
Is 3 to 4 on three of the four rounds of the lead portion 21, respectively.
Each is provided.

In this embodiment, the lead frame 20 has a plate thickness of 0.12 mm, a longitudinal length of 160 mm, and a widthwise length of 6 mm.
1mm, the width of slit 27 is 0.6mm, and the connecting part
The width of each piece 26a, 26b, 26c of 26 is 0.2 mm, and the net length of the absorbing piece 26c is 1 mm.

In the manufacturing process of the semiconductor package, as in the conventional example, first, the inner leads 22, 22,
The inner end of ... and the conductive parts 12, 1 of the printed wiring board 10, ...
Connect and fix the outer ends of 2,…, then the printed wiring board
The semiconductor element 30 is mounted on the mounting portion 11 of 10, using a resin die-bonding agent or the like (semiconductor element mounting process), and then each terminal portion of the semiconductor element 30 and each conductive portion 12, 12 ,. The end portion is connected with a thin metal wire 31 such as gold (wire bonding step). The state so far is as shown in FIG. 3 which is drawn in a simplified manner. Next, as shown in FIG. 4, the region including most of the inner leads 22, 22, ...
Insert into 2, 33 and perform resin molding (resin molding process).
FIG. 5 shows the semiconductor package P taken out from the resin molding dies 32, 33, and the semiconductor element 30 is sealed with resin 34. Then, the lead portions 21, 21 ... Are cut at a predetermined position and protruded from the package which is the resin molding portion, specifically, the outer leads.
Bend 23, 23, ... as appropriate (cutting and bending process). In the lead frame 20 of this embodiment, three semiconductor packages are manufactured.

In the semiconductor element mounting process and the wire bonding process in the manufacturing process, the lead frame 20 is placed in an atmosphere of a temperature of about 220 ° C., work is performed, and the substrates are sequentially transported. In this temperature atmosphere, the expansion amount of the latter becomes large due to the difference in thermal expansion coefficient between the lead frame 20 and the printed wiring board 10. Therefore, although stress is applied to the lead frame 20, the stress is absorbed by the absorbing piece 26c positioned so as to extend in a direction substantially orthogonal to the expansion or contraction direction of the printed wiring board 10. As a result, warp deformation of the lead frame 20 is reduced. Of course, even if the reverse stress is applied by changing from the high temperature atmosphere to the low temperature atmosphere, the same operation is performed.

As a result of a comparative experiment conducted by the applicant of the present invention between the present embodiment and the conventional example, the warp was 1 mm or less, which was reduced to about 1/3 of the conventional example.

Next, a second embodiment of the present invention will be described with reference to FIG. This is different from the first embodiment only in the structure of the connecting portion 26. The connecting portion 26 is formed by the connecting piece 26d and the slit forming piece 26e.

The connecting piece 26d is substantially the same as the conventional connecting portion and is located in the direction of expansion or contraction of the printed wiring board 10, and basically connects the lead frame 20 and the lead frame 21. To do.

The slit forming piece 26e is a strip on the lead portion 21 side formed by providing a slit 26f longer than the lateral width of the connecting piece 26d on the lead frame 20 outside the lead portion 21. The connecting piece 26e described above is continuously provided near the center of the slit forming piece 26e. In addition, this slit forming piece 26e
May be provided on the lead portion 21 or both.

In this case, when stress is applied to the lead frame 20, the slit forming piece 26e absorbs the stress.

Next, a third embodiment of the present invention will be described with reference to FIG. This is also different from the first embodiment only in the structure of the connecting portion 26, and is a combination of the slit forming pieces of the first and second embodiments.

That is, the connecting portion 26 includes a lead portion side protruding piece 26a which protrudes outward from the lead portion 21 in parallel with the outer leads 23, 23, ..., and a lead frame 20 outside the lead portion 21. The lead frame side projecting piece 26b projecting inward at a position parallel to the outer leads 23, 23, ..., And the absorption provided continuously to the tip parts of the projecting pieces 26a, 26b in the direction orthogonal thereto. A slit forming piece formed by providing a slit 26f longer than the lateral width of both projecting pieces 26a and 26b on the piece 26c and the lead frame 20 outside the lead portion 21.
Formed by 26e.

In this device, when stress is applied to the lead frame 20, the stress is applied to the slit forming piece 26e and the absorbing piece 26e.
c absorbs.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.
It will be described based on. This is the connecting portion of the first embodiment.
It is a modification of 26.

That is, the connecting portion 26 has, as a basic shape, a lead portion side protruding piece 26a, a lead frame side protruding piece 26b, and an absorbing piece 26c, which are similar to those of the first embodiment. Specifically, as shown in FIG. 9, one of the projecting pieces 26a and 26b is made long and the other is made short, and approximately half of the absorbing piece 26c is U-shaped. As shown in FIG. 8, the absorbing piece 26c has its U-shaped portion bent substantially at a right angle to form a bent portion 26g.

In this case, when stress is applied to the lead frame 20, the bending portion 26g absorbs the stress.

The structure and shape of the connecting portion 26 are not limited to those of the embodiment, but may be formed in a curved shape,
It may be inclined or the width may be changed. That is, it is important to note that the connecting portion 26 is formed along the expansion or contraction direction of the printed wiring board 10 as in the conventional example, that is, the stress is not formed on the lead frame 20 in such a manner that the stress is stretched. It is to provide an absorbing piece that absorbs. In addition, the connecting portion 26 is 3 of the 4 rounds of the lead portion 21.
The number is not limited to the one provided on the circumference, but may be four as a matter of course (in the present embodiment, the one located at the center is provided on the fourth), and may be provided at least at two orthogonal turns. .

Further, when the frame portion 25 is bent at least on one side portion in the longitudinal direction and the printed wiring board 10 has a high rigidity structure in the juxtaposed direction as compared with the lead portion 21, the warp can be further reduced. . As the means for providing this highly rigid structure, it is possible to select an appropriate means such as forming a rib or attaching another member.

[0043]

The composite lead frame according to claim 1 is
Since the connecting portion absorbs the stress on the lead frame when the printed wiring board expands or contracts, deformation of the lead frame due to temperature change can be reduced.

In the composite lead frame according to the present invention, the slit forming piece of the connecting portion absorbs the stress to the lead frame when the printed wiring board expands or contracts, and the deformation of the lead frame due to the temperature change can be reduced. .

In the composite lead frame according to the third aspect of the present invention, the stress applied to the lead frame when the printed wiring board expands or contracts is absorbed by the absorbing piece of the connecting portion, and the deformation of the lead frame due to temperature change can be reduced.

In the composite lead frame according to the present invention, the stress applied to the lead frame when the printed wiring board expands or contracts is absorbed by the slit forming piece and the absorbing piece of the connecting portion. Deformation can be further reduced.

In the composite lead frame according to the present invention, the bending of the connecting portion absorbs the stress to the lead frame when the printed wiring board expands or contracts, so that the deformation of the lead frame due to temperature change is further reduced. it can.

In the composite lead frame according to the sixth aspect, in addition to the effects of the first to fifth aspects, the frame portion is less likely to be deformed, and the deformation of the lead frame due to the temperature change can be further greatly reduced.

[Brief description of drawings]

FIG. 1 is a partial plan view showing a first embodiment of the present invention,
Inner leads and conductive parts are drawn in a simplified manner.

FIG. 2 is an enlarged plan view of the connecting portion.

FIG. 3 is a perspective view showing a state in which the printed wiring board and inner leads are connected and fixed.

FIG. 4 is a sectional view showing the resin molding state.

FIG. 5 is a sectional view showing a state where the resin molding is completed.

FIG. 6 is a partial plan view showing a second embodiment of the present invention.

FIG. 7 is a partial plan view showing a third embodiment of the present invention.

FIG. 8 is a partial perspective view showing a fourth embodiment of the present invention.

FIG. 9 is a partial plan view before the completion.

FIG. 10 is a plan view showing a conventional example, in which inner leads and conductive portions are simplified and drawn.

FIG. 11 is an enlarged plan view of the connecting portion.

[Explanation of symbols]

 10 Printed wiring board 11 Placement part of printed wiring board 12 Conductive part of printed wiring board 20 Lead frame 21 Lead part of lead frame 22 Inner lead of lead part 23 Outer lead of lead part 25 Frame part of lead frame 26 Lead frame Connecting part 26a Connecting part lead side projecting piece 26b Connecting part lead frame side projecting piece 26c Connecting part absorbing piece 26d Connecting part connecting piece 26e Connecting part slit forming piece 26f Connecting part stress absorbing slit 26g Connecting part Bent part 27 Frame slit 28 Frame positioning hole

Claims (6)

[Claims] 1. A printed wiring board on which a conductive portion is formed so as to extend outward corresponding to each terminal portion when a semiconductor element is placed at a predetermined position, and a plurality of printed wiring boards are arranged in parallel. A lead portion composed of an inner lead for connecting and fixing the outer ends of the respective conductive portions and an outer lead serving as a terminal of the semiconductor package, and the lead portion are supported through a connecting portion provided around the lead portion and the printed wiring board In a composite lead frame having a lead frame provided with a frame portion extending in the juxtaposed direction, a connecting portion of the lead frame is formed so that stress to the lead frame can be absorbed when the printed wiring board expands or contracts. A composite lead frame. 2. The lead frame connecting portion includes a connecting piece positioned in a direction of expansion or contraction of the printed wiring board, and a stress absorbing slit longer than a lateral width of the lead portion and the lead frame outside the lead portion. The composite lead frame according to claim 1, wherein the composite lead frame is formed by a slit forming piece provided on at least one side. 3. The lead frame connecting portion is formed so as to be displaced from each other, the lead portion side protruding piece, the lead frame side protruding piece outside the lead portion, and a direction substantially orthogonal to the expansion or contraction direction of the printed wiring board. The composite lead frame according to claim 1, wherein the composite lead frame is formed by an absorbing piece in which the tip portions of both projecting pieces are continuously provided so as to extend in the direction. 4. At least one of the lead-side projecting piece and the lead frame-side projecting piece has a stress absorbing slit longer than the lateral width of the lead-side projecting piece and the lead frame-side projecting piece outside the lead section and the lead section. 4. The composite lead frame according to claim 3, wherein the composite lead frame is connected to a slit forming piece formed on at least one of the two lead frames. 5. The composite lead frame according to claim 3, wherein a bent portion bent in a U-shape is formed on a part of the absorbing piece. 6. The frame portion of the lead frame,
The composite lead frame according to any one of claims 1 to 5, wherein a structure in which the printed wiring boards are arranged side by side has a high rigidity structure as compared with the lead portions.