JPH08330493A - Continuous manufacture of mask and lead frame - Google Patents

Abstract

PURPOSE: To make continuous multiple lead frame obtaining by etching possible, by making masks wherein the joints of cutting-off mask lines by each shot continue. CONSTITUTION: In the pattern regions 3 of masks 1, 2, a plurality of streaks of lead frame patterns 5 each of which continues in the longitudinal direction are drawn in the width direction. Among the lead frame patterns 5, 5, cutting-off mask line patterns are drawn so as to jut out from the pattern regions 3 into nonpatterning regions 4. By using these masks l, 2, it becomes possible to prevent joints of the cutting-off mask lines by each shot from being discontinuous, on the occasion of exposure by step and repeat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous manufacturing method of lead frames by an etching method.

[0002]

2. Description of the Related Art In recent years, attention has been focused on a method of manufacturing a lead frame in which a plurality of lead frame patterns are printed in parallel on one metal strip in the width direction and are separated by etching to obtain multiple strips.

Conventionally, a method has been adopted for this stripping of the lead frame, in which the etching and stripping steps are carried out in a reel shape, and after stripping, the strips are cut into sheets. Originally, it is more efficient to work with the reel type as much as possible, but switching to the single-wafer type from the middle is a strip that does not require continuity because it is difficult to have continuity at the seam for each one-shot exposure. This is because it is formed in a pattern.

FIG. 7 shows such a conventional single-wafer metal strip 30.
An example of a one-shot of a strip lead frame pattern burned on is shown. Large strip 3 surrounded by frame 31 and suspension 32
3 are formed in three rows. Six small strips 34 are arranged in each of the three large strips 33. There are 6 pieces of the lead frame 35 in one small strip. Therefore, 3 per sheet
A lead frame of × 6 × 6 = 108 pieces is attached.

The frame 31 and the suspension 32 are provided in the pattern to prevent the strips from falling when the strips are taken by etching. Note that, as shown in FIG. 8, the single-wafer metal strip 30 is cut from the metal strip into single-wafers and cannot be reeled. Moreover, it is cut into small strips by a work called frame cutting later.

[0006]

However, the above-mentioned conventional technique has various problems as follows.

(1) Since it is a single sheet, it requires complicated handling such as a device such as a robot or manpower for transport, and the sheet is clogged or flaps, rotation failure of the transport roller, clogging due to slip, etc. (Jamming) may occur, the manufacturing cost is high and the productivity is poor.

(2) The frame and the hanging portion are lost, and the material resources cannot be effectively used.

(3) Frame cutting work is required.

(4) The supply to the post-process inspection (including an automatic visual inspection device), the plating process, the depressing machine, the tape applying machine, etc. is limited to strips and cannot be supplied in the continuous reel system, which is inefficient.

An object of the present invention is to provide a mask which enables etching to be performed in a reel type. Another object of the present invention is to provide a continuous manufacturing method of a lead frame which can solve the above-mentioned problems of the prior art by using the mask.

[0012]

A mask of the present invention has a pattern region in the center and a non-pattern region in the periphery, and lead frame patterns are continuously formed in the length direction in the pattern region and a plurality of lines are drawn in the width direction. A mask line pattern for separation is drawn between the lead frame patterns of each strip, protruding from the pattern area to the non-pattern area.

A method for continuously producing a lead frame according to the present invention comprises a step of successively forming a resist film on a metal strip fed from a feeding reel in the continuous method for producing a lead frame in which a lead frame is stripped from a metal strip by etching. The step of overlaying the mask on the metal strip on which the resist film is formed, and removing the resist film of the portion not exposed by exposure / development, and then etching the portion, the multiple strips separated from the mask line for separation And the step of winding the separated lead frame on a take-up reel.

In this case, the step of superposing the mask on the metal strip on which the resist film is formed is performed by the upper mask supported by the outer vacuum frame rubber bank and the inner vacuum frame rubber bank located inside the outer vacuum frame rubber bank. The metal strip is vacuum-adsorbed between the upper mask and the lower mask on which the same pattern is drawn, and at this time, the inner end face of the inner vacuum frame rubber bank is drawn on the upper and lower masks of the lead frame pattern. It is better to match the edge.

[0015]

If the mask line pattern for separating the lead frames from each other is drawn outside the pattern area on the mask, even if the lead frame pattern is not continuous at the seam after each one-shot exposure, the separation is performed. The mask line for use is continuously formed without being cut in the middle. Therefore, when multiple lead frames are formed by etching from metal strips,
The etching can surely separate the lead frames from each other at the same time.

Further, when the masks are stacked from above and below the metal strip, if the inner end surface of the inner vacuum frame rubber bank is aligned with the ends of the lead frame patterns drawn on the upper and lower masks,
The loss portion in the longitudinal direction can be eliminated, and the lead frame pattern can be continuously printed on the metal strip.

[0017]

Embodiments of the present invention will be described below.

In order to continuously take multiple strips of the lead frame by etching with a reel type, the mask is not formed into a strip-shaped pattern, but is formed into a continuous pattern without the frame and suspension, and the pattern is formed by etching. It is enough to insert a separation line between the patterns. However, in the case of a continuous pattern, if discontinuity occurs at the seam of the separation line for each one-shot exposure, the separation cannot be performed there. If there is a portion that cannot be separated even at one place, it will not be possible to continuously wind the reel. Therefore, in the present invention, a pattern area is provided in the center and a non-pattern area is provided around the lead area. In the pattern area, a plurality of lead frame patterns are continuously formed in the length direction and a plurality of pieces are drawn in the width direction. The mask line pattern for use is drawn so as to extend from the pattern area to the non-pattern area so that the seam of the cut lines for each shot is not discontinuous.

FIG. 1 is a plan view of the mask of this embodiment, where (a) is an upper mask and (b) is a lower mask. The patterns drawn on the upper mask 1 and the lower mask 2 are exactly the same, and the only difference is that the overall size of the upper mask 1 is slightly larger than that of the lower mask 2.

No frame or hanging pattern is present in the rectangular pattern area 3, and the lead frame pattern 5 is continuously drawn in 6 rows in the width direction and 18 pieces 7 in the length direction. Therefore, 6 × 18 = 108 for one mask.
The lead frame of the piece is faced.

A separation mask line pattern 6 for separating the lead frames from each other is drawn linearly between the lead frame patterns 5 and 5 in the width direction along the length direction. The separation mask line pattern 6 does not stop at the pattern area 3 but extends to the non-pattern area 4 outside the pattern area 3. In the illustrated example, the separation mask line pattern 6 reaches the left and right ends of the masks 1 and 2 and cuts the entire length of the masks 1 and 2, but may be cut in the middle without reaching the left and right ends. . The pattern width required for the mask line pattern 6 for separation is the etching allowance.

In order to continuously take a lead frame by reel-to-reel using the above-mentioned upper and lower masks 1 and 2, as shown in FIG. 2, a resist film is formed on the metal strip 9 fed from the feed reel 8. A resist film is sequentially formed by the coating device 10. The metal strip 9 on which the resist film is formed is sent to the exposure device 11 using the upper and lower masks 1 and 2 for exposure.

FIG. 3 shows a main part of the exposure apparatus. The upper mask 1 is supported by the outer vacuum frame rubber bank 17, and the lower mask 2
Is supported by an inner vacuum frame rubber embankment 18 located inside the outer vacuum frame rubber embankment 17, and the upper mask 1 and the lower mask 2 are supported.
The metal strip 9 is vacuum-adsorbed between and.

With this exposure device, the metal strip 9 is exposed in a step-and-repeat manner such as the ultraviolet irradiation area 23 of the previous shot, the ultraviolet irradiation area 22 of the current shot, and the ultraviolet irradiation area 21 of the next shot.
When ultraviolet rays are applied, the lead frame pattern and the mask line pattern for separation are not exposed to ultraviolet rays, and the other portions are exposed. At this time, in order to eliminate the loss portion in the longitudinal direction, the end surface of the lead frame pattern and the inner end surface 18a of the inner vacuum frame rubber embankment 18 need to be perfectly aligned with each other, and moreover, the ultraviolet rays should not be completely irradiated twice. Must be shielded from light.

An example of pattern printing of the metal strip 9 after exposure is shown in FIG. There is no frame or suspension, and the product pattern is continuously formed on the entire surface of the metal strip 9 like a stamped product.
Moreover, the separating mask line 19 is continuously formed between the patterns without a seam. Therefore, there is no material loss, and the yield in material removal can be made almost 100%. Further, since there is no frame or suspension, frame cutting work can be omitted.

This is developed by the developing machine 12, the resist film of the non-photosensitive portion is removed by the resist removing device 13, and the metal strip of the non-photosensitive portion is etched by the etching device 14. The exposed portion may be etched. Then, as shown in FIG. 5, six rows of lead frames 20 are simultaneously formed by etching, and they are separated from the separating mask line 19. At this time, since the separation mask line 19 has no seam over the entire length, separation by etching is surely performed.

After that, the resist film is stripped by the stripping device 15, and the separated lead frames 20 are individually wound on the respective winding reels 16. FIG. 6 shows a plan view of the lead frame of the primary strip wound up. In the figure,
Reference numeral 24 is an oval guide hole, and 25 is a true circle guide hole.
As described above, since the whole process can be performed in the reel type without forming a single wafer in the middle, it is possible to largely omit the robot or human power and mass-produce lead frames. Further, since it can be supplied to the subsequent process by the reel, the work efficiency is higher and the lot management is easier than the case where the sheets are separated one by one. In addition, a cutting device for cutting a single wafer is not required, and a jamming trouble of the single wafer can be eliminated.

By the way, in order to draw the separating mask line in a completely straight line and with high accuracy, the meandering correction device eliminates the meandering of the metal strip, and the metal strip and the upper and lower mask positions are preferably ± 20 μm or less, more preferably. It is necessary to have an auto-alignment device that aligns with an accuracy of ± 10 μm or less. Further, it is necessary that the position of the seam of the shot of the exposure apparatus is perfectly aligned with the end surface 18a of the rubber bank 18 on the inner side of the vacuum frame, and the guide hole pitch is accurately formed. Therefore, a high precision feed mechanism of preferably ± 10 μm or less is required. Here, the high-precision feed mechanism can control the feed length with high precision by a high-precision encoder and a high-precision pulse motor or servo motor. In addition, the pattern position accuracy in the width direction of the metal strip is also required, and the patterns need to be aligned in the longitudinal direction of the strip.

[0029]

According to the present invention, a lead frame can be continuously manufactured by a mask having a simple structure in which a mask line pattern for separation is protruded from a pattern region to a non-pattern region.

According to the present invention, a mask line for separation is continuously inserted at the joint for each one-shot exposure so that a plurality of lead frames can be separated only by etching. Therefore, the lead is reel-to-reel. The frame can be continuously stripped, and productivity can be significantly improved at low cost. Further, since the continuous reel type can be supplied to the subsequent process, the working efficiency is greatly improved.

The useless portion required for the metal strip is
In essence, only the etching cost to separate the lead frame is needed, and there is no need for a frame or suspension as in the case of stripping, so the material can be effectively used and the frame cutting work is eliminated, so workability is improved. Is greatly improved.

When the masks are stacked on top of each other from above and below the metal strip, when the inner end surface of the inner vacuum frame rubber bank is aligned with the ends of the lead frame patterns drawn on the upper and lower masks, The lead frame pattern can be continuously burned onto the metal strip without loss.

[Brief description of drawings]

FIG. 1 is a plan view of an upper mask and a lower mask according to an embodiment of the present invention.

FIG. 2 is a line configuration diagram of a lead frame continuous manufacturing method according to an embodiment of the present invention.

FIG. 3 is a side sectional view of a main part of the exposure apparatus according to the present embodiment.

FIG. 4 is a plan view of a metal strip on which a lead frame pattern is continuously and continuously printed according to this embodiment.

FIG. 5 is a plan view of a metal strip cut into a plurality of strips according to the present embodiment.

FIG. 6 is an enlarged plan view of the single lead frame according to the present embodiment.

FIG. 7 is a plan view of a sheet after pattern printing of a conventional example.

FIG. 8 is an explanatory diagram of a conventional single-wafer manufacturing method.

[Explanation of symbols]

 1 Upper Mask 2 Lower Mask 3 Pattern Area 4 Non-Pattern Area 5 Lead Frame Pattern 6 Separation Mask Line Pattern 7 Piece 8 Feeding Reel 9 Metal Strip 10 Resist Film Coating Device 11 Exposure Device 12 Developing Machine 13 Resist Removal Device 14 Etching Device 15 Film stripping device 16 Take-up reel 17 Outer vacuum frame rubber embankment 18 Inner vacuum frame rubber embankment 18a End surface 20 Lead frame

Claims (3)

[Claims] 1. A lead frame pattern having a pattern area in the center and a non-pattern area on the periphery, a plurality of lead frame patterns being continuous in the length direction and being drawn in the width direction, for separating the lead frame patterns of each row. A mask in which the mask line pattern is drawn from the pattern area to the non-pattern area. 2. A method for continuously producing a lead frame, wherein a plurality of lead frames are stripped from a metal strip by etching, a step of sequentially forming a resist film on the metal strip fed from a feed reel, and a step of forming a resist film on the metal strip. The step of stacking the mask according to claim 1, and removing the resist film of a portion which is not exposed to light by exposure and development, and then etching the portion to form a multi-row lead frame separated from the mask line for separation. 1. A continuous manufacturing method of a lead frame, comprising: a forming step; and a step of stripping a resist film and winding the separated lead frame on a winding reel. 3. A continuous manufacturing method for a lead frame according to claim 2, wherein the step of superposing the mask according to claim 1 on the metal strip on which a resist film is formed is an upper mask supported on an outer vacuum frame rubber bank. And the inner vacuum frame rubber bank located inside the outer vacuum frame rubber bank, and the metal strip is vacuum-adsorbed between the upper mask and the lower mask on which the same pattern is drawn. A continuous manufacturing method of a lead frame in which the inner end surface of the rubber bank is aligned with the end of the lead frame pattern drawn on the upper and lower masks.