JPH1197601A - Manufacture of lead frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the bending or the like of the end portion of a lead, when a lead frame having no island portion is manufactured by a photoetching method while forming a resist pattern. SOLUTION: During a patterning process for forming an end portion 3 of a lead as an etching resist pattern, etching is effected by providing a pattern 13 of the portion 3 and substantially triangular patterns that extend from both corners of the pattern 13, providing a band-like trapezoidal barrier resist pattern 15 adjacent to the portion 3, and providing a barrier resist pattern 16 at the central portion that corresponds to the island portion of a lead frame 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a lead frame using a thin metal plate, and more particularly to a method of manufacturing a lead frame having no island portions using a thin metal plate.

[0002]

2. Description of the Related Art Generally, when manufacturing a lead frame by a photo-etching method using a thin metal plate, a pattern of an etching resist is used in order to shorten the length of the lead and to make both corners of the lead tip round. As the pattern forming the lead tip, a substantially triangular pattern is provided extending at the lead tip pattern and both corners thereof, and a band-shaped trapezoidal barrier resist pattern is provided near the lead tip. I was

More specifically, FIG. 7 is an enlarged plan view of an example of a conventional method, in which a pattern of an etching resist before etching of a lead frame without an island portion is described. (33), strip-shaped trapezoidal barrier resist pattern (35),
It shows a diagonal line (XX ′) of the lead frame and the like.

FIG. 8A is a partial plan view for explaining one corner of the diagonal lead frame of FIG. 7 in an enlarged manner. FIG.
FIG. 4B is a partial plan view illustrating an enlarged diagonal corner of a lead frame without an island portion after etching, which is an example of a conventional method. In FIG. 8B,
The pattern (23) of the lead tip after etching, the diagonal line (XX ') of the lead frame and the like are shown. As a thin metal plate serving as a lead frame, for example, a plate thickness of about 0.
In the case of a copper plate of 125 mm, as shown in FIG.
The width (a ′) of the resist pattern (33) at the tip of the lead before etching is about 10 mm and the width (b) of the slit is about 0.10 mm, as shown in FIG. 0.15mm, slit width (b ')
Is about 0.05 mm. In FIG. 8A, the resist pattern at the tip of the lead is a pattern in which both corners are extended in a substantially triangular shape. FIG. 8A,
In (b), c denotes the pitch of the lead tip, and c ′ denotes the pitch of the resist pattern at the lead tip.

As shown in FIG. 8A, a strip-shaped trapezoidal barrier resist pattern (35) is provided near the resist pattern (33) at the tip of the lead as an etching resist pattern before etching. Have been. As described above, for example, in a copper plate having a plate thickness of about 0.125 mm, in FIG. 8A, the distance (h ′) between the resist pattern (33) at the tip of the lead and the strip-shaped trapezoidal barrier resist pattern (35). Is about 0.10mm,
Width (d ') of the trapezoidal barrier resist pattern (35)
Is about 0.08 mm, and the distance (f ') between the strip-shaped trapezoidal barrier resist patterns (35) is about 0.07 mm.
mm.

In FIGS. 8 (a) and 8 (b), i represents the difference between the resist pattern (33) at the tip of the lead before etching and the pattern (23) at the tip of the lead after etching. This is a correction value for correcting the amount by which the side surface of the metal sheet is etched by the side etching. In FIG. 8A, a strip-shaped trapezoidal barrier resist pattern (35) is provided in the vicinity of the leading end of the lead, which reduces the length of the lead and makes the two corners of the leading end circular. It is to prevent.

[0007] In photoetching, the etching amount of a metal sheet changes depending on the density of a region to be etched which is not covered with a photoresist. That is, when the region to be etched not covered by the photoresist is large per unit area, the amount of etching is large, and when the region to be etched not covered by the photoresist is small per unit area, Is less etched.

For example, as shown in FIG. 8B, the area to be etched is large per unit area in the vicinity of the tip of the lead of the lead frame. This causes rounding of both corners of the lead tip. In order to prevent such occurrence, as shown in FIG. 8A, for example, a band-shaped trapezoidal barrier resist pattern (35) is provided to correct the density.

Generally, a resist pattern provided to correct the density of a region to be etched is called a barrier resist pattern. The position and size of the barrier resist pattern are set so as not to be formed as a pattern after etching.

In photo etching, a sheet-like metal sheet is manufactured by being etched while being conveyed in an etching apparatus. In a conventional method, however, the sheet metal sheet is etched by a conveying roll for conveying the metal sheet. The leading end of the lead may come into contact with the lead, causing the leading end of the lead to bend.

That is, FIG. 5 shows a strongly acidic etching solution,
FIG. 3 is a cross-sectional view of an example of an etching apparatus (70) in a spray etching method using a ferric chloride solution.
In FIG. 5, a large number of transport rolls (72) are arranged in parallel, and a large number of nozzles (74) for spraying an etchant are arranged above and below the transport roll. FIG.
FIG. 3 is a plan view illustrating an example in which a lead frame without an island portion is manufactured by attaching a plurality of lead frames to a thin metal plate, and a resist pattern is formed on the front and back surfaces of the thin metal plate (4).

The metal sheet (4) having the resist pattern formed on the front and back surfaces is transported from left to right in FIG. 5, and is etched by an etching solution from above and below while being transported. In FIG. 5, arrows indicate the traveling direction of the metal sheet and the rotation direction of the transport roll. The arrangement interval (J) of the transport rolls is, for example, about 20 cm, and the diameter of the transport rolls is about 2 to 3 cm.

As a metal thin plate, for example, a plate thickness of about 0.12
A copper plate having a size of 5 mm and a size of about 50 × 50 cm is used. The metal sheet is etched while being transported from left to right,
In the latter half of the etching process, in a situation where the parts other than the pattern part of the lead frame are dissolved and the lead tip is formed, the lead tip contacts the surface of the transport roll,
The lead tip may bend. The size of the central blank portion of the lead frame is, for example, about 0.
In the case of a copper plate of 125 mm, it is particularly likely to occur when the size is about 30 × 30 mm or more.

[0014]

As described above, when a lead frame without an island portion is formed by forming a resist pattern by photo-etching, the lead resist is formed as an etching resist pattern. When manufactured by extending a substantially triangular pattern at the lead tip pattern and both corners thereof, and by providing a strip-shaped trapezoidal barrier resist pattern near the lead tip, the transfer roll of the etching apparatus is manufactured. The tip of the lead may come into contact with the surface, causing bending or the like at the tip of the lead. The present invention provides a method of manufacturing a lead frame having no island portion without forming such a bend or the like at a lead end portion when a lead frame is formed by forming a resist pattern by a photoetching method. Things.

[0015]

According to the present invention, there is provided a method for manufacturing a lead frame having no island portion by forming a resist pattern by a photo-etching method. A method for manufacturing a lead frame, comprising: providing a barrier resist pattern that supports a leading end of a formed lead and falls off by an etching end point, and performs etching. Further, the present invention provides the lead frame manufacturing method according to the above invention, wherein the barrier resist pattern has a cross shape and is provided on a diagonal line at a central portion of the lead frame. is there.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The manufacturing method of the present invention will be described below based on one embodiment. FIG. 3 is a plan view showing one embodiment of manufacturing the lead frame (1) according to the present invention.
In FIG. 3, the central portion (2) is a blank portion without an island portion, and the lead tip portion (3) is arranged facing the central portion (2) corresponding to the island portion.
FIG. 6 is a plan view showing a region inside the lead tip portion in FIG. 3 and illustrating an etching resist pattern before the lead frame in FIG. 3 is etched.

In FIG. 6, a resist pattern (13) at the tip of the lead is arranged facing the center, and a strip-shaped trapezoidal barrier resist pattern (15) is arranged near the resist pattern (13) at the tip of the lead. Further, a cross-shaped barrier resist pattern (16) is arranged on the diagonal line at the center of the lead frame. FIG. 1A shows FIG.
FIG. 4 is an enlarged plan view illustrating one corner on a diagonal line of FIG. FIG. 1B is an enlarged plan view illustrating one corner on the diagonal line of FIG. 6 after etching. FIG. 2A shows FIG.
It is a YY 'sectional view in (a). FIG. 2 (b)
FIG. 2 is a sectional view taken along the line YY ′ in FIG.

As a thin metal plate serving as a lead frame, for example, a copper plate having a thickness of about 0.125 mm, FIG.
In (b), the width (A) of the lead tip after etching is, for example, about 0.10 mm, and the width of the slit (B).
Is about 0.10 mm, and the lead pitch (C) is about 0.20 mm. FIG.
The blank at the center (2) corresponding to the island shown in FIG.

As shown in FIG. 1A, as a pattern of an etching resist before etching, in a pattern for forming a leading end of a lead, both corners of the resist pattern are extended in a substantially square shape to form a leading end of the lead. A portion of the resist pattern (13) is arranged. As a thin metal plate serving as a lead frame, for example, in a copper plate having a thickness of about 0.125 mm, in FIG. 1B, the width (A) of the lead end after etching is, for example, about 0.10 mm, the width of the slit. For about 0.10 mm of (B), the resist pattern (1
The width (A ′) of 3) is about 0,0 as shown in FIG.
It is about 15 mm, and the width (B ') of the slit before etching is about 0.05 mm. Also,
(C ′) indicates the pitch of the resist pattern at the tip of the lead.

Before and after this etching, for example, the difference between the width (A ′) of the resist pattern at the tip of the lead about 0.15 mm and the width (A) of the tip of the lead about 0.10 mm is about 0.05 mm, and The difference (I) between the resist pattern (13) at the tip of the lead before etching and the pattern (3) at the tip of the lead after etching is about 0.025 m.
m is obtained by correcting the amount of etching of the side surface of the metal sheet as a side etch when processing the metal sheet by the photo-etching method in the resist pattern in advance.

As shown in FIG. 1A, a strip trapezoidal barrier resist pattern (15) is provided near the resist pattern (13) at the tip of the lead as an etching resist pattern before etching. ing. As described above, for example, in a copper plate having a plate thickness of about 0.125 mm, the distance (H ′) between the resist pattern (13) at the tip of the lead and the strip-shaped trapezoidal barrier resist pattern (15) in FIG. Is about 0.10mm,
Width of trapezoidal barrier resist pattern (15) (D ')
Is about 0.08 mm, and the interval (F ') between the strip-shaped trapezoidal barrier resist patterns is about 0.07 mm.

As shown in FIGS. 6 and 1, a cross-shaped barrier resist pattern (16) is arranged on the diagonal line at the center of the lead frame. The width (E ') of the cross-shaped barrier resist pattern is about 0.16 mm, and the distance (G') between the cross-shaped barrier resist pattern and the band-shaped trapezoidal barrier resist pattern is about 0.12 mm.

As described above, as a thin metal plate, for example, a copper plate having a thickness of about 0.125 mm and a size of about 50 × 50 cm, a resist pattern is formed on the front and back surfaces thereof,
As shown in FIG. 5, in the latter half of the etching step of etching while being transported from left to right, in a situation where portions other than the pattern portion of the lead frame are melted and the lead tip is formed, the lead This cross-shaped barrier resist pattern is provided in order to prevent the bend or the like from occurring at the lead tip so as not to contact the surface of the lead and cause the bend or the like from occurring at the tip of the lead.

That is, in a lead frame having no island portion, the cross-shaped barrier resist pattern provided at the center portion corresponding to the island portion comes into contact with the surface of the transport roll and supports the metal thin plate. This prevents the occurrence of bending and the like due to the contact with the surface of the device. The size of the center part of the lead frame is, for example, about 30 mm in a copper plate having a thickness of about 0.125 mm.
The effect is particularly large when the size is 30 mm or more.

FIGS. 9A to 9F show one embodiment of the manufacturing process of the lead frame (1) according to the present invention.
It is explanatory drawing represented by the Y 'cross section. In FIG. 9A,
As the plate-shaped metal thin plate (4) serving as the lead frame (1), for example, a plate thickness of about 0.125 mm and a size of about 50 × 5
Use a 0 cm copper plate.

As shown in FIG. 9 (b), the metal sheet (4)
A photoresist layer (5) is formed thereon. Next, a pair of exposure masks having substantially the same pattern, for example, a pair of substantially identical exposure masks (6) in which a portion that becomes a pattern of the lead frame is a light transmitting portion and a portion other than the pattern portion of the lead frame is a light shielding portion. , (6 ′), as shown in FIG. 9 (c), one exposure mask (6) is applied to one surface of the thin metal plate (4), and the other surface of the thin metal plate (4) is Another exposure mask (6 ') is applied. Next, by irradiating light (30) with ultraviolet light from both surfaces, the photoresist layer at a portion to be a pattern of the lead frame is photo-cured. Next, by performing development, an unexposed portion of the photoresist layer is removed, and as shown in FIG. 9D, an etching resist layer (7) exposing a metal other than a part to be a pattern of the lead frame. , (7 ′).

Next, an etching solution (40) is brought into contact with the front and back surfaces of the metal sheet to perform etching. The exposed metal sheet portion, that is, the metal sheet other than the portion that becomes the pattern of the lead frame is selectively dissolved and removed, and the metal sheet of the strip-shaped trapezoidal barrier resist pattern (15) and the cross-shaped barrier resist pattern (16) is obtained. Is melted and separated from the lead tip (3) to obtain a thin metal plate as shown in FIG. The etching is a strongly acidic etching solution,
For example, a spray etching method is employed using a ferric chloride solution. Next, the metal thin plate is washed with water and washed, the etching resist layers (7) and (7 ') are peeled off, washed with water and dried to obtain the lead frame (1) shown in FIG.

The lead frame thus obtained has no bent or the like at the lead end (3).

[0029]

According to the present invention, when a lead frame having no island portion is formed by forming a resist pattern by a photoetching method, the pattern of the lead tip portion is used as the etching resist pattern. An approximately triangular-shaped pattern is extended in both the corner pattern and both corners, a strip-shaped trapezoidal barrier resist pattern is provided in the vicinity of the lead tip, and a barrier resist pattern is provided in the center corresponding to the island portion of the lead frame. Since it is provided and the etching is performed, bending or the like does not occur at the tip of the lead.

[Brief description of the drawings]

FIG. 1A is an enlarged plan view illustrating a pattern of an etching resist at one corner on a diagonal line before etching a lead frame according to the present invention. (B)
FIG. 4 is an enlarged plan view for explaining a lead end portion at one corner on a diagonal line after etching of a lead frame according to the present invention.

FIG. 2A is a sectional view taken along the line YY ′ in FIG. 1A. (B) is a sectional view taken along the line YY 'in FIG. 1 (b).

FIG. 3 is a plan view showing one embodiment of manufacturing a lead frame according to the present invention.

FIG. 4 is a plan view illustrating an example in which a lead frame without an island portion is manufactured by attaching a plurality of lead frames to a thin metal plate.

FIG. 5 is a sectional view of an example of an etching apparatus.

FIG. 6 is an enlarged plan view illustrating a pattern of an etching resist in a region inside a lead tip portion before etching of a lead frame in FIG. 3;

FIG. 7 is an enlarged plan view illustrating an example of a pattern of an etching resist before etching of a lead frame having no island portion according to a conventional method.

FIG. 8A is a partial plan view illustrating an enlarged diagonal corner of a lead frame without an island portion before etching, which is an example of a conventional method. (B)
FIG. 4 is a partial plan view illustrating one diagonal corner of a lead frame without an island portion after etching, which is an example of a conventional method.

FIGS. 9A to 9F are explanatory views showing one embodiment of a manufacturing process of the lead frame according to the present invention, which is represented by a YY ′ section.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lead frame 2 ... Central part equivalent to an island part 3 ... Lead tip part 4 ... Metal thin plate 5 ... Photoresist layer 6 ... Front exposure mask 6 '... Back exposure mask 7 ... Front etching resist layer 7' ... Back surface Etching resist layer 13: Lead tip resist pattern 15: Trapezoidal barrier resist pattern 16: Cross-shaped barrier resist pattern 23: Lead tip in conventional method 30: UV irradiation 33: Lead resist pattern in conventional method 35: Conventional trapezoidal barrier resist pattern 40 ... Etching liquid 70 ... Etching device 72 ... Transport roll 74 ... Nozzle A ... Lead tip width B ... Slit width C ... Lead pitch A '... Lead tip resist pattern Width B ': Width of slit before etching C': Pitch of resist pattern at lead tip a: Width of lead tip in conventional method b: Width of slit in conventional method c: Pitch of lead in conventional method a ': Width of resist pattern at lead tip in conventional method b '... Slit width before etching in the conventional method c' ... Pitch of resist pattern at the tip of the lead in the conventional method D '... Width of trapezoidal barrier resist pattern d' ... Width of trapezoidal barrier resist pattern in the conventional method E ': Width of cross-shaped barrier resist pattern F': Interval between strip-shaped trapezoidal barrier resist patterns f ': Interval between strip-shaped trapezoidal barrier resist patterns in the conventional method G': Between cross-shaped trapezoidal barrier resist pattern and strip-shaped trapezoidal barrier resist pattern Distance between H ': resist pattern at the tip of lead and trapezoidal barrier Distance between the strike patterns h ′: the distance between the resist pattern at the tip of the lead and the strip-shaped trapezoidal barrier resist pattern in the conventional method I: the resist pattern at the tip of the lead before etching and the tip of the lead after etching Difference from the pattern i: Difference between the resist pattern at the tip of the lead before etching in the conventional method and the pattern at the tip of the lead after etching J: Arrangement of the transport rolls

Claims (2)

[Claims] In a method of manufacturing a lead frame having no island portion by forming a resist pattern by photo-etching, a lead portion formed in the latter half of etching is supported at a center portion corresponding to an island portion of the lead frame. A method of manufacturing a lead frame, wherein a barrier resist pattern which falls off by the end of etching is provided and etching is performed. 2. The method for manufacturing a lead frame according to claim 1, wherein said barrier resist pattern has a cross shape and is provided on a diagonal line at a central portion of the lead frame.