JP4305131B2 - Lead frame manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a lead frame, and more particularly to a method for manufacturing a lead frame in which metal pieces are not generated by contact with a transport rail in transport in post-processing of the lead frame.

  There are two methods for manufacturing a lead frame: a press method and a photo etching method. The lead frame manufacturing method by the photo-etching method is, for example, when oil or organic dust adhering to both surfaces of a metal thin plate as a material is removed with an alkaline degreasing solution and then coated with a photoresist. In order to improve the adhesion of the photoresist to both surfaces of the metal thin plate, the surface treatment with acid is performed on both surfaces of the metal thin plate.

  Next, an acrylic dry film is thermocompression-bonded (laminated) on both surfaces of the thin metal plate, and then a photomask on which a predetermined light-shielding pattern is formed is adhered to the metal surface, and pattern exposure is performed by irradiating ultraviolet rays. The photoresist layer in the region other than the light shielding pattern portion of the mask is photopolymerized.

  Next, development is performed with hot water spray to remove the photosensitive resin in the unexposed areas, and then the remaining photoresist layer is hardened and burned to form an etching resist layer. Next, spray the etching solution using the etching resist layer formed on both sides of the thin metal plate as a mask, dissolve and remove the unnecessary metal parts from both sides, and finally immerse the unnecessary etching resist layer in a hot alkali bath. This is a manufacturing method in which a lead frame having a predetermined pattern is removed.

  The lead frame on which the predetermined pattern is formed in this way may be subjected to island downset (depressing) or lead taping as post-processing.

  When post-processing is performed, the lead frame on which the predetermined pattern is formed is transported to the unit of the post-processing apparatus by, for example, a transport rail, and is transported from the unit of the post-processing apparatus by the transport rail after the post-processing.

  FIG. 1 is a plan view of an example of a transport rail of a lead frame. 2 is a cross-sectional view taken along line X-X ′ of FIG. As shown in FIGS. 1 and 2, the conveyance rail (11) shown as an example is composed of a left rail (11 </ b> A) and a right rail (11 </ b> B) having an L-shaped cross section.

  The lead frame (10) on which the predetermined pattern is formed is transported on the transport rail (11) in the direction of a white arrow.

  When the lead frame (10) is transported by such a transport rail (11), both ends of the lead frame (10) in the width direction serve as transport guides in the width direction during the transport. 11) contact the vertical part (12A, 12B), the both ends in the width direction may be broken and fall off and scatter.

  If the dropped and scattered metal pieces adhere to the lead frame and the IC is mounted with the metal pieces still attached, a failure such as a short circuit occurs and the mounted IC becomes a defective product.

3 and 4 are explanatory diagrams in which the portion P in FIG. 2 is enlarged. As shown in FIG. 3, the upper and lower surfaces (a, b) of the both ends in the width direction of the lead frame (10) have acute angles, and the upper and lower surfaces (a, b) of both ends are being conveyed. Vertical section (12A, 12B) of transport rail (11)
) Breaks, falls off, and scatters by contacting with each other, and a part thereof adheres to the lead frame.

  Then, both end portions in the width direction of the lead frame are in a state in which acute angle portions are missing as shown in FIG.

  FIGS. 5A and 5B are explanatory views of a situation in which both end portions in the width direction of the lead frame (10) become acute angles as shown in FIG. FIG. 5A shows a state in which an etching resist layer (22) is formed on both surfaces of the metal thin plate (21), and shows a state before being etched with the etching solution.

  5 (a) and 5 (b) show one end of the thin metal plate (21), and the lead frame pattern portion in the central etching resist layer (22) is not shown.

  When etching is performed on both sides of the thin metal plate (21) in this state, the etching solution also flows into both end portions, and both end portions of the thin metal plate (21) are etched. As shown in FIG. The upper and lower surfaces (a, b) of both end portions of the thin plate (21) are acute angles.

  The present invention has been made in order to solve the above-described problem. When post-processing is performed on a lead frame on which a predetermined pattern is formed, both end portions in the width direction of the lead frame are transported by the transport rail. It is an object of the present invention to provide a method for manufacturing a lead frame in which both end portions in the width direction of the lead frame are not bent and scattered as metal pieces even if they contact the vertical portion of the rail.

The present invention provides a lead that is conveyed in post-processing by conveying rails having both ends in the width direction coming into contact with the vertical portion of the conveyance rail by a conveyance rail composed of a left rail and a right rail whose cross-sectional shape has a vertical portion. In a lead frame manufacturing method in which an etching resist layer is formed on both surfaces of a thin metal plate and manufactured by a photoetching method, both ends of the thin metal plate are parallel to the transport direction of the lead frame after etching when the etching resist layer is formed. A dummy pattern that extends linearly in the transport direction and extends in the width direction from the part, exposes the thin metal plate, and is located on both sides of the thin metal plate simultaneously with the formation of the etching resist layer. formed in, etched from both sides of the metal sheet, by penetrating the sheet metal of the dummy pattern portion, further both ends than the dummy pattern By removing or dissolving the metal thin plate portion in the metal thin plate, the upper and lower surfaces of the portions that become new end portions in the width direction of the metal thin plate by etching and come into contact with the vertical portion of the conveyance rail after etching are removed. A lead frame manufacturing method is characterized in that each of the angles formed by the side surfaces is an obtuse angle in a sectional view.

In the lead frame manufacturing method according to the present invention, when the metal thin plate is a copper material having a thickness of 0.125 mm and the etching resist layer has a thickness of 0.015 mm to 0.020 mm, The width of the dummy pattern exposing the thin plate is 0.015 mm to 0.020 mm, and the width of the etching resist layer at the end of the dummy pattern is 0.04 mm to 0.06 mm. It is a manufacturing method.

  In the present invention, an exposed portion of a thin metal plate extending linearly in the longitudinal direction is used as a dummy pattern in the vicinity of both ends of the thin metal plate parallel to the longitudinal direction of the lead frame. Since it is a manufacturing method of the lead frame to form, the cross section of the upper and lower surfaces of both ends becomes an obtuse shape.

  Therefore, when post-processing is performed on a lead frame on which a predetermined pattern is formed, even if both ends of the lead frame in the width direction come into contact with the vertical portion of the transport rail during transport by the transport rail, the width direction of the lead frame It is possible to provide a lead frame in which both end portions are not bent and scattered as metal pieces.

  Thereby, the defect of metal piece adhesion in IC mounting resulting from the contact with the conveyance rail in the post-processing of the lead frame is reduced.

  Below, the manufacturing method of the lead frame by this invention is demonstrated based on embodiment.

  FIG. 6A is a plan view for explaining an example of the lead frame in the manufacturing process in the lead frame manufacturing method according to the present invention. FIG. 6B is a cross-sectional view taken along line Y-Y ′. 6 (a) and 6 (b) show a state in which an etching resist layer (62) made of a dry film is formed on both surfaces of the metal thin plate (61), and shows a state before being etched with the etching solution. Show.

  In FIG. 6A, the portion indicated by (64) represents the position where the predetermined pattern of the lead frame is formed by the etching resist layer (62), but the details of the predetermined pattern are omitted. It is.

  As shown in FIGS. 6A and 6B, the lead frame of this example is provided with an etching resist layer (62) on both surfaces of the metal thin plate (61). An exposed portion (dummy pattern) (63) of the thin metal plate extending linearly in the longitudinal direction is provided in the vicinity of both ends of the thin metal plate (61) parallel to the longitudinal direction of the lead frame indicated by the arrow.

  The exposed portions (63) of the thin metal plate are provided on both surfaces of the thin metal plate (61), and the exposed portions (63) on both surfaces have the same position. The exposed portion (63) of the thin metal plate is provided as a dummy pattern, and the portion of the thin metal plate located at both ends of the exposed portion (dummy pattern) (63) of the thin metal plate is a metal at the end point of etching. That is, it is detached from the thin plate (61).

  Further, the exposed portion (63) of the metal thin plate is formed on both surfaces of the metal thin plate simultaneously with the formation of the etching resist layer (pattern shape) of the portion indicated by (64) for forming a predetermined pattern as a lead frame by etching. It is formed.

  In FIG. 6A, the direction of the arrow is parallel to the transport direction in post-processing.

  7A to 7C are explanatory views of a method for manufacturing a lead frame according to the present invention. FIG. 7A is an enlarged view of the Q portion in FIG. 6B, and details of a predetermined pattern of the lead frame are omitted as in FIG.

  When the metal thin plate (61) at the stage shown in FIG. 7 (a) is etched from both sides, the etching solution acts on the exposed portions (dummy patterns) (63) on both sides of the metal thin plate, and both end surface portions, The thin metal plate (61) in that portion is dissolved and removed (FIG. 7B), and finally the exposed portion of the thin metal plate penetrates.

  A portion of the metal thin plate located further on both ends of the exposed portion (dummy pattern) (63) is detached from the metal thin plate (61) at the end point of etching, or is dissolved and removed.

  As shown in (c) and (d) of FIG. 7C, the upper and lower surfaces of the obtained lead frame that become the new end face are not obtuse but obtuse.

  Thus, the lead frame manufactured by the lead frame manufacturing method according to the present invention has obtuse angles on the upper and lower surfaces of both ends of the lead frame. Even if it contacts the vertical part of a conveyance rail, both ends will not be broken.

  Specifically, when a copper material having a plate thickness of 0.125 mm is used as the material of the metal thin plate (61), the thickness (D3) of the etching resist layer (62) is set to 0.015 mm to 0.020 mm, The width (D2) of the exposed portion (dummy pattern) (63) of the metal thin plate is 0.015 mm to 0.020 mm, and the width (D1) of the etching resist layer at the end portion further from the exposed portion is 0.04 mm to 0.04 mm. Etching was performed at 06 mm to obtain a lead frame in which the cross sections of the upper and lower surfaces of both end portions were obtuse.

It is a top view of an example of the conveyance rail of a lead frame. It is sectional drawing of the X-X 'line | wire of FIG. It is explanatory drawing of the acute angle part which expanded the P part in FIG. It is explanatory drawing of the state which expanded the P part in FIG. 2, and the acute angle part was missing. (A) is explanatory drawing of the condition where both ends become an acute angle thing in the stage in which the etching resist layer was formed.

(B) is explanatory drawing of the condition where both ends become acute angles at the stage where etching is completed.
(A) is a top view explaining an example of the lead frame in the manufacturing process in the manufacturing method of the lead frame by this invention.

(B) is sectional drawing of the YY 'line | wire of Fig.6 (a).
(A)-(c) is explanatory drawing of the manufacturing method of the lead frame by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Lead frame 11 in which the predetermined pattern was formed ... Conveying rail 11A ... Conveying rail left rail 11B ... Conveying rail right rail 12A, 12B ... Conveying rail vertical part 21, 61 ... Metal thin plates 22 and 62 ... Etching resist layer 63 ... Exposed portion of metal thin plate (dummy pattern)
64: Position D1 where the predetermined pattern of the lead frame is formed by the etching resist layer D2: the width of the etching resist layer at the end portion further than the exposed portion D2: the width D3 of the exposed portion of the metal thin plate ... Etching resist layer thickness a, b ... Both ends c, which are acute in the width direction, ... Both ends, which are obtuse in the width direction

Claims (2)

The lead frame that is transported in the post-processing by the conveyance rail composed of the left rail and the right rail having the L-shaped cross section having the vertical portion and having both ends in the width direction in contact with the vertical portion of the conveyance rail is a metal thin plate. In a lead frame manufacturing method in which an etching resist layer is formed on both sides of the substrate and manufactured by a photoetching method, when the etching resist layer is formed, the width direction from both ends of the thin metal plate parallel to the transport direction of the etched lead frame Inside, a dummy pattern that extends linearly in the transport direction and exposes the metal thin plate, the dummy pattern having the same position on both sides is formed on both surfaces of the metal thin plate simultaneously with the formation of the etching resist layer, etched from both sides of the metal sheet, said dummy pattern portion of the sheet metal to penetrate, gold is still at both ends than the dummy pattern By removing or dissolving the thin plate portion from the metal thin plate, the upper and lower surfaces and the side surfaces of the portion that comes into contact with the vertical portion of the transport rail after etching become a new end portion in the width direction of the metal thin plate by etching. A lead frame manufacturing method, characterized in that each formed angle is a lead frame in an obtuse angle in a cross-sectional view.   When the metal thin plate is a copper material having a thickness of 0.125 mm and the thickness of the etching resist layer is 0.015 mm to 0.020 mm, the width of the dummy pattern exposing the metal thin plate is 0.015 mm to 0.00. 2. A method of manufacturing a lead frame according to claim 1, wherein the width of the etching resist layer at the end portion of the dummy pattern is 0.04 mm to 0.06 mm.

Images