JP5610449B2 - Lead frame - Google Patents

Description

The present invention relates to a lead frame processed into a strip shape and a method of manufacturing a semiconductor package using the lead frame.

  In general, a lead frame is formed by forming a pad portion or a lead portion by pressing or etching a metal material having a thickness of 0.1 to 0.25 mm into a predetermined pattern, and a plurality of lead frames are about 200 mm long. The strips are packed in a stacked state and transported to an assembly process for mounting semiconductor elements. Even a single sheet formed in a strip shape is called a lead frame.

  When a plurality of lead frames are stacked, the stacked lead frames may rub against each other and cause problems such as deformation and scratches. Therefore, a slip sheet called dust-free paper or resin-made interleaving paper is sandwiched between lead frames to prevent problems.

  However, when the interleaving paper is used, an interleaving paper that matches the product shape is required, and there is a problem that not only the cost of the interleaving paper but also the cost for the interleaving paper volume and weight are required. In addition, it is necessary to insert an insertion sheet when manufacturing the lead frame, and to remove the insertion sheet when assembling the semiconductor package using the lead frame.

  Therefore, in Patent Documents 1 and 2, the lead frame is bent to form a protrusion so that a gap is formed when the lead frames are stacked so that the insertion sheet is not used. A method for preventing deformation and scratches of the lead frame is described.

  Patent Document 1 discloses a lead frame in which a punch is abutted against a lead frame outer frame portion to be recessed, and a hemispherical protrusion is formed on the opposite side. When the lead frames are stacked, an interval corresponding to the height of the projection is provided.

  Further, in the lead frame and the manufacturing method thereof described in Patent Document 2, a die and a punch are used for the lead frame, and the clearance between the punch and the die is made larger than in the case of normal punching. The interval when stacked is obtained by performing half-punching of about / 4 to 1/6.

JP-A-53-66170 JP-A-6-177309

  However, when a protrusion is formed on the lead frame so as not to use an interleaving sheet, the protrusion is released to a jig or the like in each process in advance so that the protrusion does not interfere in the assembly process of the semiconductor package. It was necessary to apply the processing for. If there is a process that cannot be processed even in one process, a method of forming a protrusion shape on the lead frame cannot be adopted.

  Therefore, the present invention has been made to solve the above-described problems, and even when the lead frames are stacked, no interleaving paper for preventing scratches or deformation of the lead frame is required, and the interleaving paper is used. An object of the present invention is to provide a lead frame and a method of manufacturing a semiconductor package using the lead frame, which reduce the cost and the like and do not require modification or new production of jigs and tools in the conventional semiconductor package assembly process.

  In order to achieve the above object, the lead frame of the present invention has two rising portions formed on the outer frame portion of the lead frame having a strip shape by raising the bent frame from the outer frame portion, and A desired number of bending patterns are formed in which deformed portions including deformable bent portions are connected to the tip ends of the two raised portions, and the orientation of the bending pattern is It is characterized by being arranged so as to be a position rotated 90 degrees by half of the desired number.

  In the present invention, it is preferable that at least one bent portion is formed in the deformable portion.

  In the present invention, it is preferable that the two raised portions are formed so that the raised tips face each other.

  In the present invention, it is preferable that the width of the deformed portion is narrower than the width of the bent portion.

  In the present invention, the width of the bent portion is 1.5 times or more the thickness of the lead frame, and the width of the deformed portion is 0.8 to 1.2 times the thickness of the lead frame. preferable.

  Alternatively, the lead frame of the present invention is characterized in that the above lead frame is used and the bending pattern is bent so as to protrude to the side on which the semiconductor element is mounted.

  In the present invention, it is preferable that the bending pattern is formed so that a rising portion is formed by rising at the bent portion, and the deforming portion expands. The height of the raised portion is more preferably higher than the bending height of a portion called a tab, island or pad of the lead frame.

In the present invention, it is preferable that the bent pattern for bending is flattened by returning to the original shape by a pressing process.

  According to the present invention, it is possible to stably stack the lead frames by preventing the shift in the width direction and the longitudinal direction of the lead frames without using the interleaf paper after manufacturing the lead frames, and in the assembly process of the semiconductor package. In addition, it is possible to provide a lead frame that does not require improvement of jigs and tools. Further, by not using the interleaving paper, it is possible to reduce not only the cost of the interleaving paper but also the transportation cost of the product and improve the productivity.

It is a top view which shows an example of the lead frame which has arrange | positioned the pattern for bending process of this invention in the outer frame part. It is a side view which shows the state which laminated | stacked the lead frame of this invention. It is an enlarged plan view of the pattern for bending before bending. It is an enlarged plan view of the pattern for bending after crushing. It is an enlarged side view of the pattern for bending after bending. It is an expansion perspective view of the pattern for bending after bending. It is an enlarged plan view which shows the other example of the pattern for bending before a bending.

Hereinafter, modes for carrying out the present invention will be described.
In the lead frame of the present invention, the tip raised by rising from the outer frame portion at the bent portion is formed on the outer frame portion of the strip-shaped lead frame. Two raised portions formed so as to face each other, and a deformed portion having a bent portion so that the width is narrower than the bent portion and connected to the tips of the raised portions of the two raised portions so as to be deformable. A desired number of patterns for bending are formed. Further, the bending pattern is arranged so as to be in a positional relationship of being rotated by 90 degrees by half of a desired number in order to prevent displacement in the width direction and the longitudinal direction of the lead frame.

  By forming this bending pattern on the outer frame portion of the lead frame having sufficient metal material, no warping or deformation occurs even when bending is performed at a wide bent portion. Then, the rising portion intentionally reduces the plate thickness until the rising portion prevents interference in the stacked state. This can prevent the lead frame from being displaced in the planar direction. At this time, the bent portions connected to the mutually raised tips maintain the shape before the startup processing.

  In addition, the semiconductor package manufacturing method of the present invention includes two rising portions formed by rising from the outer frame portion at the bent portion on the outer frame portion of the strip-shaped lead frame, and a width wider than the bent portion. Bending that forms the desired number of bending patterns to form a deformable deformable part by connecting the tips of two raised parts that are raised at a narrow bent part and forming a deformable deformable part. The processed bending pattern is then brought into contact with another lead frame and conveyed in a state in which a plurality of lead frames are stacked, and then one lead from the stacked state in any subsequent process After the frame is taken out, the bending pattern that has been bent is pushed back to be substantially flat, and the process is then put into the subsequent steps.

  At the time of bending, it is bent so that the raised part is raised at the wide bent part, but the bent part connected to the tip of each other reduces the thickness of the raised part. The previous shape is maintained. On the other hand, in the assembly process of the semiconductor package, it is necessary to deform the bent portion by pushing back the bending pattern so that the bent portion is returned to a substantially flat shape. In order to reliably return to the original shape by pushing down, the rising angle is set to 85 degrees or less.

Next, an embodiment of the lead frame of the present invention will be described with reference to the drawings.
FIG. 1 shows a strip-shaped lead frame 1. A bending pattern 3 as shown in FIG. 3 is formed on the outer frame portion 2 of the lead frame 1 in the upper and lower portions of FIG. In the example of FIG. 1, the bending pattern 3 is arranged at the same pitch as the wiring pattern pitch, but may be arranged intermittently. In the example of FIG. 1, the bending pattern 3 has a 90-degree difference in the vertical direction. However, the arrangement is not limited thereto as long as the patterns differ in the 90-degree direction.

  Here, the bending pattern 3 formed in the present invention will be described in more detail with reference to FIGS. The bending pattern 3 is provided on the outer frame portion 2 of the lead frame 1 having a strip shape. Then, the leading end 5 of the rising portion 6 raised by rising from the outer frame portion 2 at the bent portion 4 is the tip of the other rising portion 6 'similarly raised at the bent portion 4'. Two raised portions 6, 6 'formed so as to face each other 5', and the raised ends of the two raised portions 6, 6 ', which are narrower than the bent portions 4, 4', It is composed of a deformed portion 8 which is connected to the portions 5 and 5 'and has a bent portion 7 which can be deformed so as to open. In the illustrated example, the bent portion 7 of the deformable portion 8 has a Z shape in plan view. However, if the deformable portion 8 can be deformed, the bendable portion 7 may be at least one or more. The angle of the bent portion 7 can be arbitrarily selected as long as it can be deformed at the time of start-up or push-back.

  The bending pattern 3 can be simultaneously formed on the outer frame portion 2 when the lead frame 1 is manufactured by pressing or etching. For example, the bending pattern 3 is formed in the same manner as forming the internal leads and pads of the lead frame 1 by pressing or etching the band-shaped metal material. Then, plating is performed, and then, when cutting into a strip shape of about 200 mm, bending processing (start-up processing) is performed so that the flat bending processing pattern 3 is raised upward. To do.

  In addition, there is a method of manufacturing in the form of a ribbon or a sheet after the above pattern formation. For example, in the case of a method using a manufacturing process in the form of a ribbon, the pad part (chip mounting part) is used as the final process of manufacturing the lead frame. In this process, in addition to the pressing process of the pad portion, the bending pattern 3 may be raised in this process.

Next, the manufacturing method of the semiconductor package of this invention using the said lead frame is demonstrated.
In the method of manufacturing a semiconductor package according to the present invention, bending is performed to a height necessary for the bending pattern 3 of the lead frame 1. Basically, the bent portions 4 and 4 ′ are bent so that the bending pattern 3 protrudes on the side where the semiconductor element is mounted, and the rising portions 6 and 6 ′ are larger than the thickness of the lead frame 1. Have a bending height. Basically, the rising angle A at the bent portions 4 and 4 'shown in FIG. When the rising portions 6 and 6 'are raised, the distance between the opposed tips 5 and 5' is widened, and the deformed portion 8 connected to the tips 5 and 5 'is deformed in the direction in which the bent portion 7 is widened. It will be. Since the bent portions 4, 4 'are wider than the deformable portion 8 and sufficiently strong, only the raised portions 6, 6' are deformed, and the raised portions 6, 6 'are raised. It will not be deformed.

  Next, as shown in FIG. 2, the bent pattern 3 is conveyed so that a plurality of lead frames 1 are stacked so that the bent pattern 3 is in contact with another lead frame. Then, after one lead frame 1 is taken out from the laminated state in an arbitrary step thereafter, the bent pattern 3 is bent back to the state shown in FIG. To be thrown into. As a method of pushing back almost flatly, for example, when pressing with a mold (resin-sealed) mold, it is pushed back, but it may be performed with a jig or other device in another process.

  Originally, the lead frame 1 is transported in the assembly process of the semiconductor package with the surface on which the semiconductor element is mounted as the front surface side (upper surface side), and therefore, as shown in FIG. When viewed from above, bending processing (start-up processing) is performed so that the bending pattern 3 faces upward. Then, the shape to be bent needs to be arranged after removing the place where it hits the equipment device or the conveying device in the assembly process of the semiconductor package. In other words, the outer frame part of a normal lead frame is a flat outer frame part only having a positioning through-hole, and therefore it is assumed that the lead frame of the flat outer frame part is handled on the equipment. Designed to.

  Therefore, since the equipment is shared even if the lead frame changes, the present invention can be fixed by returning the bending pattern to the original without affecting the conveyance by bending upward. Sometimes it has a flat outer frame. In addition, when the resin is sealed after entering the mold, if the plate is forcibly returned so that a part of the bending pattern overlaps, the height of the plate thickness + α is partially generated, and the mold and the lead frame There is a risk that a gap will be formed between and the resin will leak. For this reason, a pattern that returns to the original so as not to overlap is required, and the expanded deformed portion is pressed into the mold die in the same plane and deformed again to become flat.

  In general, the bending process is performed by reducing the thickness of the slanted portion (rising portion) to be bent and extending the length to ensure the distance (elongation) by bending, so that the bent portion 7 of the deformable portion 8 is closed. To absorb the distance (elongation).

  The bending pattern 3 is formed on the outer frame portion 2 of the lead frame 1, but it may have a shape obtained by rotating FIG. 3 by 90 degrees, and as shown in FIG. Then, it may be rotated 90 degrees on the upper and lower sides. Moreover, as shown in FIG. 6, you may make it provide in four places of upper and lower, right and left. Or it is set as arbitrary two of these, and the front-end | tip of two raising parts does not necessarily need to oppose.

  Then, after being put into the assembly process of the semiconductor package, it can be pushed down in a plane from the upper surface of FIG. 5, and the bending pattern 3 returns to the flat state during the assembly process. In order to ensure that this push-down can be performed reliably, the rising portions 6 and 6 'are raised from the outer frame portion 2 of the lead frame 1 by the bent portion 4, and the upper surface becomes a surface as shown in FIG. It is necessary to secure the deformed portion 8 connected to the distal ends 5 and 5 'and to raise the rising portions 6 and 6' at the bent portions 4 and 4 'so that the rising angle A is 85 degrees or less. .

  According to the present invention, it is possible to provide an overlapping lead frame and a method for manufacturing the same, which do not require modification or new creation of jigs and tools in a semiconductor package assembly process.

DESCRIPTION OF SYMBOLS 1 Lead frame 2 Outer frame part 3 Bending pattern 4, 4 'Bending part 5, 5' Tip part 6, 6 'Rising part 7 Bending part 8 Deformed part A Rising angle

Claims (8)

A deformable deformable portion integrally connecting a pair of raised portions raised from the outer frame portion at a bent portion and a tip portion of the pair of raised portions to an outer frame portion of a lead frame having a strip shape A desired number of bending patterns are formed, and the orientation of the bending pattern is arranged so that the half of the desired number is rotated by 90 degrees. Lead frame.   The lead frame according to claim 1, wherein at least one bent portion is formed in the deformable portion.   3. The lead frame according to claim 1, wherein the pair of raised portions are formed such that the raised tips are opposed to each other.   The lead frame according to claim 1, wherein a width of the deformed portion is narrower than a width of the bent portion.   The width of the bent portion is 1.5 times or more the thickness of the lead frame, and the width of the deformed portion is 0.8 to 1.2 times the thickness of the lead frame. Lead frame as described in. Using a lead frame according to claim 1, wherein the bending pattern is rie de, characterized in that bending so as to protrude on the side where the semiconductor element is mounted has been subjected flame. The bending pattern is rie de frame according to claim 6, characterized in that it is formed by raising the rising portion. The bending pattern of the folded, the lead frame according to claim 6 or 7, characterized in that the flat by returning to the original by the depressing process.

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