JPH04324664A - Set sheet of lead frame - Google Patents

Abstract

PURPOSE:To prevent the generation of crock when insulative base material is unified in a body, by forming dummy patterns which have many holes almost similarly to individual lead frames, in the parts of a set sheet where the individual lead frames and a frame body are not formed. CONSTITUTION:A frame body 11 in which tool holes and the like are bored is formed on the outer periphery of a set sheet 10, and a dummy pattern 13 having the same pattern as an individual lead frame 12 is formed in the part positioned between the frame body 11 and each lead frame 12. Insulative base material for constituting an electronic mounting board is unified in a body with the surface and the rear of the set sheet 10 by thermo-compression bonding. Thereby softened parts of the insulative base material are mutually bonded through many holes of the individual lead frames 12 and the dummy patterns 13. The greater part of the finely divided set sheet 10 are buried in the insulative base material. Hence the insulative base material is unified in a body with the set sheet without leaving stress, so that crook is not generated at all in the set sheet.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembly sheet in which a number of lead frames for configuring a board for mounting electronic components are formed as a series from a single metal plate.

0002

[Prior Art] In recent years, various electronic component mounting substrates have been proposed for configuring semiconductor devices on which electronic components such as semiconductor elements are mounted and have a large number of external connection terminals. People have already proposed various types of substrates for mounting electronic components that enable high-density mounting and facilitate manufacturing by integrating insulating base materials on both sides of a lead frame. The electronic component mounting board proposed by the applicant employs a lead frame that integrates a large number of leads that serve as external connection terminals.
A large number of lead frames are formed as a series from a single metal plate. In other words,
A large number of individual lead frames corresponding to one electronic component mounting board are assembled into a sheet shape, and a sheet-shaped insulating base material is integrated on both sides of this assembly sheet to form a predetermined pattern. After that, each electronic component mounting board is individually cut out.

[0003] As described above, when a large number of individual lead frames are assembled into a series to form an aggregate sheet, it is not only necessary to manufacture the aggregate sheet itself, but also to create an insulating base material for each electronic component mounting board. It is very advantageous industrially because integration, formation of necessary patterns (conductor circuits), necessary plating, and various associated treatments can be performed all at once and continuously. However, even with such an advantageous collection sheet, studies by the present inventors have revealed that the following problems may occur.

[0004] In other words, an aggregate sheet is a series of many individual lead frames, and when an insulating base sheet with a large area is integrated into this aggregate sheet by thermocompression press, "curvature" occurs in the whole. It was foreseen that it would be obtained. The cause of this "curvature" is thought to be the difference in thermal expansion coefficient between the metal plate that makes up the aggregate sheet and the insulating base material integrated on both sides of the aggregate sheet, or the difference in the thermal expansion coefficient of the metal plate. This includes differences in metal density depending on the pattern shape. If this "curvature" occurs, if you try to mount the entire device on each device and perform various processing operations, not only will it not be possible to mount each device correctly, but also it will not be possible to correctly form a pattern on an insulating base material. This means that you will not be able to do so.

[0005] Therefore, the inventors of the present invention have completed the present invention as a result of various studies on how to prevent the "curvature" that may occur in the collective sheet etc. .

[0006]

[Problems to be Solved by the Invention] The present invention has been made based on the above-mentioned circumstances, and the problem to be solved is to
curvature”.

[0007]An object of the present invention is to prevent curvature from occurring when the insulating base material is integrated, thereby making it possible to prevent the occurrence of curvature in each step of constructing a board for mounting electronic components. To provide a collection sheet with a simple configuration that allows work to be done easily and reliably.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the means taken by the present invention are explained by adding the reference numerals used in the embodiments. By integrating insulating base materials on both sides, a large number of individual lead frames 12 constituting an electronic component mounting board are formed as a series from one metal plate, and the outer periphery is formed from the metal plate. A dummy pattern 13 substantially similar to each individual lead frame 12 is formed in a part of the aggregate sheet 10 that does not become each individual lead frame 12 and the frame 11. 10” is a lead frame assembly sheet 10 characterized by the following.

That is, in the assembly sheet 10 according to the present invention, each individual lead frame 12 and frame body 11 are not formed and the vacant portion is provided with each individual lead frame 12.
A complex-shaped dummy pattern 13 having a large number of holes is actively formed in substantially the same manner as in FIG.

0010

Effect of the Invention In the aggregate sheet 10 according to the present invention constructed as described above, each individual lead frame 12
It goes without saying that the front and back sides of the aggregate sheet 10 are connected to each other by, for example, a large number of patterned holes formed between the respective leads. The fact that the front and back sides are connected through such a large number of pattern holes means that the dummy patterns 13 formed in substantially the same manner as each individual lead frame 12
The same is true for . For this reason, this collection sheet 10
, if we look at the metal plates before they are formed, they are very segmented even though they are connected to each other, and the rigidity of the initial metal plates is the same as the frame 11.
Almost all of them have disappeared except for.

When the insulating base material for configuring the electronic component mounting board is integrated on the front and back sides of the assembly sheet 10 in the above state by thermocompression bonding, a softened part of the insulating base material becomes attached to each individual lead frame. 12 and the dummy patterns 13 through a large number of holes, and most of the finely divided parts of the aggregate sheet 10 are embedded in the insulating base material. Therefore, each insulating base material has a collective sheet 1
The insulating base materials are integrated without any residual stress, and the aggregate sheet 10 in which the respective insulating base materials are integrated does not have any curvature at all. In addition, in the frame 11 of the aggregate sheet 10, since the insulating base materials located on the front and back sides are not bonded to each other, some stress may remain due to the difference in thermal expansion coefficient with the insulating base materials. However, since it is rare that an insulating base material is integrated over the entire surface of the frame 11, the residual stress can be completely ignored. In other words, since this frame 11 is often used as a mount part when passing through various devices, this frame 11
It is extremely rare for an insulating base material to be integrated over the entire surface of a substrate.

[0012] In each step of constructing a board for mounting electronic components by employing the aggregate sheet 10 as described above, almost no curvature occurs in the aggregate sheet 10 or the insulating base material integrated therewith. Therefore, various devices can be mounted in a perfect state, and as a matter of course, there is no curvature at all in the completed electronic component mounting board.

[0013]

[Embodiments] Next, the assembly sheet 10 according to the present invention will be explained in detail according to each embodiment shown in the drawings, but before that, it will be explained how this assembly sheet 10 is used. This will be explained with reference to FIG.

FIG. 4 shows electronic components mounted on individual electronic component mounting boards constructed using the assembly sheet 10 according to the present invention, and the entire circuit board being assembled, leaving leads to serve as external connection terminals. A cross-sectional view of a semiconductor device completed by molding with a molding resin is shown. The electronic component mounting board used in this semiconductor device is
It is constructed by integrating insulating base materials on both sides of the aggregate sheet 10 according to the present invention, and then cutting the insulating base materials into individual lead frames 12. That is, the electronic component mounting board used in this semiconductor device is formed by cutting out so-called multiple pieces using the aggregate sheet 10 as a core material, and the insulating parts are individually cut by cutting around the individual lead frames 12. The base material is integrated.

One of the materials for forming a large number of electronic component mounting substrates is the assembly sheet 10 shown in FIG. 1 or 2.

(Embodiment 1) FIG. 1 shows a first embodiment of an aggregate sheet 10 according to the present invention. It is formed by processing by means such as etching. In the assembly sheet 10 of this embodiment, one lead frame is made up of four individual lead frames 12, and six lead frames are arranged horizontally, making a total of two lead frames.
It is equipped with four individual lead frames 12. A frame 11 in which tool holes etc. are formed is formed on the outer periphery of the collective sheet 10, and individual lead frames 11 are placed between the frame 11 and each lead frame.
A dummy pattern 13 having the same pattern as 2 is formed.

The assembly sheet 10 in this embodiment is formed by etching using a so-called photo solder resist, but by using the negative for forming the pattern of each individual lead frame 12 as it is, each dummy A pattern 13 is formed together with an individual lead frame 12. In other words, this set sheet 1
0 is the frame 11 that is absolutely necessary to handle this mechanically.
A dummy pattern 13 having the same pattern as the individual lead frame 12 is formed in a portion other than each individual lead frame 12 while keeping the size of the lead frame to a minimum size.

(Embodiment 2) FIG. 2 shows a second embodiment of the collection sheet 10 of the present invention.
In 0, the frame 11 is formed slightly inside,
A plurality of individual lead frames 12 are provided outside this frame 11.
Each dummy pattern 13 is formed so as to be shifted by half a pitch with respect to the arrangement of lead frames (represented as vertically long rectangles in FIG. 2) formed by arranging the lead frames. In addition, in this embodiment assembly sheet 10, by forming a large number of slits 14 between each lead frame, the same effect as that of the dummy pattern 13 can be obtained with each slit 14.
I am also trying to make this happen.

In each of the above embodiments, each dummy pattern 13 is formed in the same manner as the individual lead frame 12, but each dummy pattern 13 has a complex shape similar to that of each individual lead frame 12. It is sufficient if the hole area is . In that sense, Figure 3
It is also possible to form the patterns shown in (a) to (d) in advance at a predetermined position on the metal plate, and then form the individual lead frames 12 in the required pattern. . In this case, each dummy pattern 13 may be formed by punching, for example, and each individual lead frame 12 may be formed by etching on the metal plate on which the dummy pattern 13 is formed. It is.

[0020]

[Effects of the Invention] As detailed above, in the present invention,
As exemplified in each of the above embodiments, "a large number of individual lead frames 12 that are constructed by integrating a large number of leads, and that constitute a board for mounting electronic components by integrating an insulating base material on both sides of the lead frame 12," An aggregate sheet 10 formed as a series of one metal plate and provided with a frame 11 formed of the metal plate on the outer periphery, each individual lead frame 12 and frame 11 of this aggregate sheet 10.
The feature lies in the fact that a dummy pattern 13 that is substantially similar to each individual lead frame 12 is formed in a portion where the insulating base material is not curved. This makes it possible to provide an assembly sheet with a simple structure that can facilitate and ensure the work in each process for configuring it as a board for mounting electronic components.

[Brief explanation of drawings]

FIG. 1 is a plan view of a collective sheet according to a first embodiment of the present invention.

FIG. 2 is a plan view of a collective sheet according to a second embodiment of the present invention.

[Figure 3] Other types of dummy patterns (A)
It is an enlarged plan view divided into - (d) and shown.

FIG. 4 is an enlarged cross-sectional view of a semiconductor device formed using an electronic component mounting substrate constructed using an aggregate sheet according to the present invention.

[Explanation of symbols]

10 Set sheet 11 Frame body 12 Individual lead frame 13 Dummy pattern 14 Slit

Claims (1)

[Claims] Claim 1: A single metal plate connects a large number of individual lead frames that constitute a board for mounting electronic components by integrating a large number of leads and integrating insulating base materials on both sides of the individual lead frames. A collective sheet having a frame formed of the metal plate on the outer periphery, and a portion of the collective sheet that does not become the individual lead frame and the frame is provided with the individual lead frame and the frame body. A collection sheet of lead frames characterized by forming substantially similar dummy patterns.