JP3551628B2 - Back sheet for lead frame - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a backsheet for a lead frame, which is used when stacking frames in which a plurality of lead frames are imposed on a sheet metal plate, and inserted between the frames.
[0002]
[Prior art]
Conventionally, a lead frame used for a semiconductor integrated circuit device or the like is manufactured by a photo-etching method or a press punching method using a mold, and an integrated circuit chip is mounted on the lead frame to form a semiconductor integrated circuit device. When mounted, 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. FIG. 3 shows an example in which five lead frames 4 are imposed in the horizontal direction.
[0003]
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 metal plate 3 In this case, individual semiconductor integrated circuit devices are obtained by punching from a semiconductor device.
[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 the two 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 mounting step of the integrated circuit chip.
[0005]
Further, for the sake of production management, the manufactured frame 2 may be temporarily stored in a warehouse or the like, and then transferred to the integrated circuit chip mounting process.
[0006]
In general, lead frames are mass-produced, and when storing or transporting a lead frame in the form of the frame 2, it is general that a plurality of frames 2 are stacked.
[0007]
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 the drawing, a slip sheet called a back sheet for a lead frame (hereinafter, simply referred to as a back sheet 1) having an outer shape substantially the same as that of the frame 2, for example, a rectangular shape, is inserted and interposed between the frames 2. It is used as a cushioning material.
[0008]
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 portion 5 is formed in the back sheet 1 so that the depressed portion can be accommodated.
[0009]
[Problems to be solved by the invention]
When stacking the frames 2, it is necessary to make the front, rear, left, right, 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.
[0010]
However, when the direction of the frame is different from front to back, 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.
[0011]
Therefore, the orientation of the stacked frames 2 needs to be constant.
However, when the frames 2 are stacked, the direction of the frames 2 is not always constant, and the frames 2 having different directions may be mixed.
[0012]
Therefore, after stacking the frames 2, it is necessary to inspect whether or not the frames 2 having different directions are mixed.
[0013]
Conventionally, for the purpose of mounting the frame 2 at a predetermined position on a device used in a process of mounting an integrated circuit chip, as shown in FIG. , And a positioning pin hole (hereinafter simply referred to as a pin hole 6). When the frame 2 is mounted on the apparatus, the pin holes 6 formed in the frame 2 are fitted into positioning pins (not shown) provided on the apparatus, so that the frame is positioned at a predetermined position on the apparatus. Are placed on the
[0014]
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 vertically. If the directions of the frames 2 are the same, it can be said that, for example, when light is applied to the stacked frame group from below, 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.
[0015]
However, the conventional back sheet 1 has substantially the same shape as the outer shape of the frame, and also has only the window portion 5 and the like formed in the depressed portion as necessary. When the back sheet 1 is inserted between the two, the back sheet covers the six pin holes, and the above-described inspection cannot be performed.
[0016]
For this reason, when the conventional back sheet 1 is used, even if the frames 2 having different directions are mixed, it can be said that it is extremely difficult to detect the frames 2 having different directions from the many stacked frames 2. In the mounting process of the integrated circuit chip or the like, a trouble such as a stoppage of work due to mixing of frames having different directions has occurred.
[0017]
An object of the present invention has been made in view of the above-described problem, and when inspecting and detecting a frame having a different direction from a large number of stacked frames based on a pin hole, the inspection and detection are easily performed. This is to provide a back sheet that can be said.
[0018]
[Means for Solving the Problems]
That is, the present invention, when stacking a frame in which a plurality of lead frames are imposed on a sheet metal plate, a lead frame back sheet inserted between each frame,
A notch is provided that allows visualization in a normal stacked state with respect to at least the pin holes located asymmetrically with respect to 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.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment will be described below with reference to the drawings schematically showing an embodiment of the present invention.
[0020]
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, and further forms the window 5 for accommodating the depressed portion of the lead frame if necessary.
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.
[0021]
That is, as described above, when the conventional backsheet is inserted into the frame 2 and the frame 2 and the backsheet are overlapped with each other, the pinholes 6 are shielded from light, and light is transmitted through the pinholes 6. This makes it impossible to inspect the orientation of the frame 2.
Therefore, the inventors of the present invention have made intensive studies to solve the above-described problem, and propose to provide a notch 7 in the back sheet 1.
[0022]
The notch 7 exposing the pin holes 6 of the frame 2 is provided in the back sheet 1, so that the pin holes 6 used for the above-described inspection are not shielded from light, and the above-described frame 2 of the frame 2 is transmitted by light. The orientation can be checked.
[0023]
Next, as a feature of the present invention, the location of the notch 7 provided in the back sheet 1 is such that the pin holes 6 which are at least asymmetrical with respect to the top, bottom, left and right of the frame 2 among the pin holes 6 formed around the frame 2. Is a place to be exposed.
[0024]
That is, normally, it can be said that all the pin holes 6 formed around the frame 2 are not formed at symmetrical positions with respect to the upper, lower, left, and right sides of the frame. If all the pin holes 6 are formed symmetrically 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 will be different from those of the frame 2 in the normal direction. This is the same as the position of the pin hole 6. In this case, the positioning pins provided in the integrated circuit chip mounting device or the like coincide with the pin holes 6 of the frame 2 having different directions, and the frame having the different direction is directly mounted on the device. In order to prevent this and to detect the frame 2 having a different orientation, when the frames 2 having different orientations are stacked, the pin holes are located at positions different from the pin holes 6 of the frames 2 having other normal orientations. At least one of them is formed at an asymmetric position with respect to the top, bottom, left and right of the frame.
[0025]
For example, in the examples of FIGS. 1 and 2, the pin holes 6 a and 6 b and the pin hole 6 c are formed at asymmetric positions with respect to the left and right sides of the frame 2.
[0026]
As shown in the examples of FIGS. 1 and 2, the notch 7 provided in the back sheet 1 of the present invention has at least The pin holes 6 formed at positions that are asymmetric with respect to up, down, left, and right are provided at locations where the pin holes 6 are exposed.
[0027]
That is, when the frames 2 are stacked, the back sheet 1 provided with the cutouts 7 as described above is inserted between the frames 2 in the same direction, so that the back sheets 1 are formed at asymmetric positions with respect to the top, bottom, left, and right of the frames 2. The pin holes 6 are not shielded from light by the back sheet 1, and the above-described orientation inspection by the pin holes 6 can be performed. That is, when light irradiation is performed, for example, from below the stacked frame group, if all the frames 2 are in the same direction, the pins formed at the uppermost frame 2 are formed at asymmetric positions with respect to up, down, left, and right. In the hole 6c, it is possible to visually or mechanically detect the passed irradiation light. Further, when 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 asymmetrical position with respect to the top, bottom, left and right of the top frame 2. The irradiation light to be detected is not detected, and it can be determined that frames having different directions are mixed.
[0028]
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 can be made 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]
【The invention's effect】
When stacking the frames, if the back sheet of the present invention is inserted and interposed between the frames, the above-described inspection and extraction of the frames in different directions using light can be performed.
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 back sheet for a lead frame 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 backsheet.
[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)

When stacking frames in which a plurality of lead frames are imposed on a sheet metal plate, in a back sheet for a lead frame inserted between each frame,
Of the positioning pin holes drilled around the frame, at least a positioning pin hole at an asymmetric position with respect to the top, bottom, left and right of the frame was provided with a notch that was visible in a normal stacked state. A lead sheet for a lead frame.

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