JPH1012803A - Back-sheet for lead frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back-sheet wherein, among piled-up frames wherein a plurality of lead frames are surface-bonded to sheets of metal, frames of different orientation are inspected and detected easily based on a pin hole opened in the frame. SOLUTION: When frames 2 wherein a plurality of lead frames 4 are surface- bonded to sheets of metal are piled up, relating to a back-sheet 1 for the lead frame inserted among the frames 2, a cutout 7 which allow visual observation, in normal piled-up state, of at least a positioning pin hole which is position s asymmetrically in longitudinal and lateral direction s of the frame 2, out of positioning pin holes 6a, 6b and 6c opened around the frame 2, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backsheet for a lead frame which is used when stacking frames having a plurality of lead frames imposed on a sheet metal plate and inserted between the frames.

[0002]

2. Description of the Related Art Conventionally, lead frames used in semiconductor integrated circuit devices and the like are manufactured by a photo-etching method or a press punching method using a mold. When mounting an integrated circuit chip on a semiconductor device, as shown in FIG. 3, a plurality of lead frames 4 are imposed on a single metal plate 3 in a so-called frame 2 form. is there.
FIG. 3 shows an example in which five lead frames 4 are imposed in the horizontal direction.

After mounting the integrated circuit chips on the individual lead frames 4 imposed on the frame 2, after performing processes such as bonding between the pads of each integrated circuit chip and each lead frame and molding with resin, The individual semiconductor integrated circuit devices are obtained by punching from the metal plate 3 or the like.

[0004] The manufacturing process of the lead frame and the mounting process of the integrated circuit chip cannot be said to be a continuous process, and it can be generally said that the distance between both processes is large.
At this time, after the lead frame is manufactured, it is necessary to transfer the lead frame in the form of the frame 2 to a process of mounting the integrated circuit chip.

[0005] Further, for the sake of production control, the manufactured frame 2 may be temporarily stored in a warehouse or the like, and then transferred to an integrated circuit chip mounting process.

Generally, lead frames are mass-produced, and when storing or transporting a lead frame in the form of a frame 2, it is general to stack a plurality of frames 2 together. .

When the frames 2 are stacked, the upper and lower lead frames 4 come into contact with each other to prevent the lead frame 4 from being damaged or deformed. As shown in FIG. 3, a slip sheet called a back sheet for a lead frame (hereinafter simply referred to as a back sheet 1), which is substantially the same shape as the frame 2, for example, a rectangular shape, is inserted between the frames 2.
It is intended to be interposed and used as a cushioning material.

Incidentally, the lead frame 4 shown in the example of FIG. 3 has been subjected to a process called depressing in which an island 8 for mounting an integrated circuit chip is one step lower than the other surface. A window 5 is formed in the backsheet 1 so that the depressed portion of the lead frame can be accommodated.

[0009]

When the frames 2 are stacked, it is necessary to make the front, rear, left and right or front and back directions of each frame 2 constant. That is, the mounting process of the integrated circuit chip is automated, and is programmed in advance so that the frames are automatically extracted one by one from the stacked frame group and the integrated circuit chip is mounted at a predetermined position of the frame. Things.

However, if the direction of the frame is different between front and rear, right and left, or front and back, it can be naturally said that the integrated circuit chip cannot be mounted at a predetermined position on the frame.

Therefore, the orientation of the stacked frames 2 needs to be constant. But frame 2
Are stacked, the direction of the frame 2 is not always constant, and there is a possibility that the frames 2 having different directions are mixed.

Therefore, after stacking the frames 2, it is necessary to inspect whether or not the frames 2 having different directions are mixed.

Conventionally, for the purpose of mounting the frame 2 at a predetermined position on an apparatus used in a mounting process of an integrated circuit chip, as shown in FIG. Is provided with a positioning pin hole (hereinafter simply referred to as a pin hole 6). Frame 2
When the frame is placed on the apparatus, the frame is placed at a predetermined position on the apparatus by fitting a pin hole 6 formed in the frame 2 with a positioning pin (not shown) provided on the apparatus. Is placed.

Therefore, it can be said that the inspection of whether or not the orientation of the stacked frames 2 is constant can be performed by using the above-described pin holes 6. That is, if the directions of the frames 2 are the same when the frames 2 are stacked, it can be said that the pin holes 6 overlap in a vertical line. Each frame 2
If the directions are the same, it can be said that, when light is irradiated to the stacked frame group from below, for example, the light passes through the pin holes 6 that are vertically aligned. Therefore, by inspecting whether or not the irradiated light passes through the pin holes 6 of the uppermost frame 2, it is possible to inspect whether or not the directions of the frames 2 are all the same. It is what becomes.

However, the conventional back sheet 1 has substantially the same shape as the outer shape of the frame, and only has the window 5 and the like formed in the depressed portion as necessary. When the back sheet 1 is inserted between the frames 2, the back sheet covers the pin holes 6 so that the above-described inspection cannot be performed.

For this reason, when the conventional back sheet 1 is used, even if the frames 2 having different directions are mixed, it is very difficult to detect the frames 2 having different directions from the many stacked frames 2. However, in the mounting process of the integrated circuit chip or the like, a trouble such as a stoppage of the work due to the mixing of frames having different directions has occurred.

An object of the present invention has been made in view of the above-mentioned problem, and when inspecting and detecting frames having different directions from a large number of stacked frames based on pin holes, it is easy to inspect and detect the frames. It is intended to provide a back sheet capable of performing detection.

[0018]

That is, the present invention provides a backsheet for a lead frame inserted between frames when stacking frames in which a plurality of lead frames are imposed on a sheet metal plate. A notch is provided to enable visual recognition in a normal stacked state with respect to a pin hole at an asymmetric position with respect to at least the top, bottom, left and right of the frame among the positioning pin holes formed around the frame. The above object has been achieved by providing a lead sheet for a lead frame described above.

[0019]

Embodiments of the present invention will be described below with reference to the drawings schematically showing embodiments of the present invention.

FIG. 1 is an explanatory view showing one embodiment of a back sheet 1 according to the present invention. As shown in FIG. 1, the backsheet 1 according to the present invention is made of a conventional material, and is inserted between the frames 2 when the frames 2 are stacked. Further, the backsheet 1 according to the present invention has the same outer shape as the frame 2 as before,
Further, if necessary, a window 5 for accommodating the depressed portion of the lead frame is formed. Here, as a feature of the backsheet 1 of the present invention, as shown in FIGS. 1 and 2, when the backsheet 1 is stacked on the frame 2, the pinhole 6 formed in the frame 2 is exposed so as to be exposed. The sheet 1 is provided with a notch 7.

That is, in the conventional backsheet, as described above, the backsheet is inserted into the frame 2 and
When the back sheet is overlaid, the pin holes 6 are shielded from light, making it impossible to inspect the orientation of the frame 2 by passing light through the pin holes 6. Therefore, the present inventors have conducted intensive studies to solve the above problems,
It is proposed to provide a notch 7 in the back sheet 1.

The notch 7 exposing the pin holes 6 of the frame 2 is provided in the back sheet 1 so that the above-described light transmission can be performed without shielding the pin holes 6 used for the inspection. The inspection of the direction of the frame 2 can be performed.

Next, as a feature of the present invention, the location of the cutout portion 7 provided in the back sheet 1 is located at an asymmetrical position in at least the up, down, left and right of the frame 2 among the pin holes 6 formed around the frame 2. This is a place where the pin hole 6 is exposed.

That is, it can be said that normally all the pin holes 6 formed around the frame 2 are not formed at symmetrical positions with respect to the top, bottom, left and right of the frame. For example, if all the pin holes 6 are formed at symmetric positions with respect to the top, bottom, left, and right of the frame 2, the positions of the pin holes 6 of the frame 2 in different directions are determined by the frame 2 having the normal orientation. The position of the pin hole 6 becomes the same. In this case, the positioning pins provided on the integrated circuit chip mounting device and the like coincide with the pin holes 6 of the frame 2 having different directions, and the frames having different directions are directly mounted on the device. In order to prevent this, and to detect the frame 2 having a different direction, for example, when the frames 2 having different directions are stacked, the pin holes are located at positions different from the pin holes 6 of the frames 2 having other normal directions. At least one of them is formed at an asymmetric position with respect to the top, bottom, left and right of the frame.

For example, in the examples of FIGS. 1 and 2,
The pin holes 6a and 6b and the pin hole 6c are formed at asymmetric positions with respect to the left and right sides of the frame 2.

As shown in the examples of FIGS. 1 and 2, the notch 7 provided in the back sheet 1 of the present invention for use in the above-described inspection of the orientation of the frame 2 at the six pin holes.
Are provided at least at locations where the pin holes 6 formed at asymmetric positions with respect to the top, bottom, left and right of the frame 2 are exposed.

That is, when the frames 2 are stacked,
By inserting the back sheet 1 provided with the notch 7 as described above between the frames 2 in the same direction, the frame 2
Pin holes 6 formed in asymmetric positions with respect to the top, bottom, left and right
The portion is not shielded from light by the back sheet 1, and the orientation can be inspected by the pin hole 6 described above. That is, when light irradiation is performed from below the stacked frame group, for example, if all the frames 2 are in the same direction, the pins formed at the asymmetrical positions with respect to the top, bottom, left and right of the top frame 2 In the hole 6c, it is possible to visually or mechanically detect the passed irradiation light.
If the frame 2 having a different direction is mixed, the frame blocks the irradiation light, and the frame 2 passes through the pin hole 6c formed at an asymmetric position with respect to the top, bottom, left and right of the top frame 2. Is not detected,
It can be determined that frames with different directions are mixed.

The embodiment of the back sheet of the present invention is not limited to the above description and drawings, and it goes without saying that various modifications are possible based on the spirit of the present invention. For example, in the above-described drawings, the cutout portion 7 is provided at two places and near the center of the back sheet 1. However, according to the position and number of pin holes formed at asymmetric positions with respect to the top, bottom, left and right of the frame 2, It can be said that the location and the number of the notches 7 may be set.

[0029]

According to the present invention, when the frames are stacked, if the back sheet of the present invention is inserted and interposed between the respective frames, the above-described inspection and extraction of the frames in different directions using light can be performed. Becomes As a result, the problem that occurred in the conventional back sheet, that is, even if a frame in a different direction is mixed, it cannot be detected, and in a mounting process of an integrated circuit chip, the work is stopped due to the mixed frame in a different direction. It is possible to prevent the problem that the obstacle occurs.

[0030]

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a lead frame back sheet of the present invention.

FIG. 2 is a plan view showing a main part of one embodiment of the back sheet for a lead frame of the present invention.

FIG. 3 is an explanatory view showing an example of a conventional lead frame back sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Back sheet 2 Frame 3 Metal plate 4 Lead frame 5 Window 6 Pin hole 7 Notch 8 Island

Claims (1)

[Claims] When stacking frames in which a plurality of lead frames are imposed on a single metal plate, a positioning sheet formed around the frames in a lead frame back sheet inserted between the frames. A backing sheet for a lead frame, wherein a notch is provided for a positioning pin hole at an asymmetric position at least with respect to up, down, left, and right of the frame. .