JPH065757A - Manufacture of lead frame excellent in shape retainability - Google Patents

Abstract

PURPOSE:To manufacture a lead frame, having large outline and high pin-count requiring a guard ring for outer lead, while preventing cost increase and deformation of outer lead, e.g. lateral bending, twisting, floating of tip. CONSTITUTION:In manufacture of lead frame comprising an inner lead 8 provided oppositely to semiconductor chip mounting part, an outer lead 2 provided continuously to the inner lead, a tiebar 9 for coupling the inner lead and the outer lead, and a holding piece 1 provided at an intermediate part of the outer lead, outer leads 2-1 on the outside of the holding piece are formed through press while other lead patterns are formed through etching or the outer leads on the outside of the holding piece are formed through etching while other lead patterns are formed through press.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a lead frame having excellent shape retention.

[0002]

2. Description of the Related Art There is a strong demand for high integration and miniaturization of semiconductor devices, and in order to meet the demand, the number of leads is increased and the leads are fine in width and pitch. Moreover, in the mounting, high density mounting is required.

The miniaturization of the leads brings about a decrease in strength thereof, and during handling, the outer leads coming out of the semi-conducting breaker in particular may be bent laterally, lifted at the tips, twisted, and deformed such as a change in pitch interval. is there. For these defective shapes, the outer lead has a predetermined shape, for example, a gull wing shape, J
This has an adverse effect on forming into a letter shape and causes a problem of uneven forming shape and contact between leads.

Further, the deformation of the outer leads causes a soldering failure when the semiconductor device is mounted on a printed board by soldering, for example. Further, in a multi-pin semiconductor device, a solder paste is applied thinly in order to prevent solder bridging, so that if the outer leads are deformed, soldering failure often occurs.

Conventionally, a guard ring has been used to prevent the deformation of the outer leads coming out of the semiconductor device. This is an endless frame body that holds the outer leads by sandwiching them. There is also a guard ring formed of resin at the same time when the semiconductor chip is mounted on the pad of the lead frame and sealed with resin.

The guard ring has the effect of holding the outer leads coming out of the semiconductor device and preventing the deformation, but it must be prepared and mounted for each semiconductor device, and the manufacturing, storage and management are troublesome and the work is complicated. Becomes Further, when the guard ring is simultaneously formed at the time of resin sealing, a manufacturing apparatus for the guard ring is required, and the forming operation also requires time.

[0007]

Therefore, it is conceivable to manufacture a lead frame in which a holding piece is formed on the outer lead. However, the lead frame requiring a guard ring has a relatively large size, and for example, 10
In many cases, the number of pins is 0 or more.

The lead frame is manufactured by pressing or etching, but in the case of manufacturing by pressing, the die must be upsized, which leads to high cost, and the press equipment row becomes long and requires space. On the other hand, if it is manufactured only by etching, it can be applied to multiple pins,
There is a problem that the frequency of exchanging the etching liquid is reduced and the productivity is not increased.

The present invention solves such a problem and manufactures a lead frame with a large outer shape and a large number of pins, which requires a guard ring on the outer leads, with high productivity at a high cost, and at the same time, the outer leads have a horizontal shape. Bend, twist,
The purpose is to obtain an excellent shape without vertical displacement of the tip.

[0010]

SUMMARY OF THE INVENTION The gist of the present invention is to provide an inner lead facing a side surface of a semiconductor chip mounting portion, an outer lead connected to the inner lead, and a tie bar connecting the inner lead and the outer lead. ,
In a method of manufacturing a lead frame having a holding piece in the middle portion of the outer lead, the outer outer lead is formed from the holding piece by pressing, and the other lead pattern is formed by etching, or the outer outer side of the holding piece is formed. This is a method for manufacturing a lead frame having excellent shape retention by forming leads by etching and forming other lead patterns by pressing.

[0011]

According to the present invention, the pattern of the lead frame is formed separately by pressing or etching on the outer side and the inner side of the holding piece provided in the middle portion of the outer lead, so that the press does not become large and the punching step is also performed. It can be shortened, lead pattern formation by etching can be done in a shorter time than forming all patterns, and the deterioration of etching solution is slow and the replacement frequency is not fast.

The lead frame manufactured according to the present invention has a large number of pins and a fine lead width and pitch,
Since a holding piece for connecting the outer lead is provided in the middle part of the outer lead and only one of the inner side and the outer side is formed by pressing, the internal residual stress accompanying punching is small, and for example, a semiconductor chip is used as a pad. Equipped with,
Even if there is a contact for some reason during the manufacturing process of semiconductor devices that are wire-bonded and sealed with resin etc., during transportation, handling, etc., the outer leads bend sideways,
Deformation such as twisting and vertical displacement of the tip portion does not occur, and the outer lead is then shaped and processed in good shape. Further, the lead interval is kept constant and there is no mutual contact, so that soldering and mounting on the printed circuit board can be performed without causing a defect.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings based on an embodiment. In the drawings, reference numeral 1 denotes a portion that serves as a holding piece for the outer lead, and the tip side 2-1 of the outer lead 2 is provided outside the holding piece 1 and is punched and formed by a press. The holding piece 1 connects the intermediate portions of the outer leads 2 so that they are not deformed even when an external force acts, and the conventional guard ring is unnecessary. The installation position is set to be slightly outside the tip position where the outer lead 2 is molded and processed into a predetermined shape from the portion where the chip is subsequently mounted on the lead frame and packaged with a sealing material such as resin. In addition,
In FIG. 1, a part of the outer lead 2 is shown on the inner side of the outer lead distal end side 2-1 with the holding piece 1 interposed therebetween, but this is shown for convenience of explanation and is a part formed thereafter. .

Reference numeral 3 denotes an etching processing region, which is surrounded by the tip end side 2-1 of the outer lead 2 formed by the press. 4 is a side rail and 5 is a guide hole. It should be noted that the outer lead portion 12 is provided on the outer periphery of the outer lead 2.
Are formed so as to relieve internal stress caused by punching.

In this embodiment, the tip end side 2-1 of the outer lead 2 is punched out in four directions, and then a photosensitive material such as a dry film 6 is attached to the material strip 7.

Next, in order to form the other side 2-2 of the remaining outer lead 2, the inner lead 8, the tie bar 9, the pad 10 and the support bar 11 in the etching processed region 3, these lead mask pacoons are positioned and baked. wear.

Subsequently, a development process is performed to remove the dry film 6 other than the exposed region through the lead mask pattern to form an etching mask.

An etching solution is jetted onto the material strip 7 having the etching mask formed thereon, and the other side 2-2 of the outer cooling lead, the inner lead 8, the tie bar 9, the pad 10,
The support bar 11 is formed. Thus, the lead frame 13 in which the holding piece 1 is provided in the middle portion of the outer lead 2
Is completed

In this embodiment, the tip side 2-1 outside the holding piece 1 in the middle of the outer lead is formed by pressing, and the other lead patterns are formed by etching.
Alternatively, the outer lead tip portion side 2-1 may be formed by etching, and other lead patterns may be formed by pressing, so that the press die can be prevented from becoming large.

In this embodiment, the holding piece 1 is formed of a group of outer leads 2 extending in each direction as a connecting unit. However, the holding piece 1 is not limited to this and is provided endlessly so as to connect the outer leads 2 in each direction. May be.

Next, the operation of the present invention will be described. When manufacturing a lead frame that conventionally requires a guard ring for the outer lead, in the present invention, the holding piece 1 provided in the middle of the outer lead 2 and the outer lead tip portion 2-1 outside the holding piece 1 are formed by pressing. Then, since the remaining lead pattern is etched and formed as described above,
The lead frame 13 can be manufactured without increasing the size of the press die.

Although the outer lead 2 has a large lead length, the internal residual stress does not increase because it is not punched and formed only by pressing. Further, since the outer lead 2 is connected to the intermediate portion by the holding piece 1, even if an external force may act during the manufacturing process or during handling, the outer lead 2 is not bent laterally, twisted, vertically deformed, or otherwise defective in shape.
These functions can be obtained even when the outer lead tip side 2-1 is formed by etching and another lead pattern is formed by pressing.

[0023]

As described above, the present invention has a large size which conventionally requires the guard ring by using the press and the etching together, and the lead frame, which requires the flatness of the Auku reed, does not increase the press die size. Can be manufactured together.

Further, the lead frame manufactured by the present invention is provided with a holding piece in the middle portion of the outer lead even if the lead is fine and the lead is fine, and either the tip side or the other side is formed by pressing. Since there is little internal residual stress, for example, a semiconductor chip is mounted on a pad, wire-bonded, packaged with resin, etc., and then the outer leads coming out of the package are cut to a specified length to form a gull-wing shape. , J-shaped molding can be performed without irregular intervals, twisting, and poor levelness, and soldering mountability on a printed circuit board is excellent.

[Brief description of drawings]

FIG. 1 is a diagram showing formation of a lead pattern by a press according to an embodiment of the present invention.

FIG. 2 is a diagram showing formation of a remaining lead pattern by etching according to an embodiment of the present invention.

[Explanation of symbols]

 1 Holding Piece 2 Outer Lead 2-1 Tip Side of Outer Lead 2-2 Other Side of Outer Lead 3 Etching Area 4 Side Rail 5 Guide Hole 6 Dry Life Film 7 Material Strip 8 Inner Lead 9 Tie Bar 10 Pad 11 Support Bar 12 Outer cut 13 Lead frame

Claims (1)

[Claims] Manufacture of a lead frame having an inner lead provided facing the side surface of the semiconductor chip mounting portion, an outer lead connected to the inner lead, a tie bar connecting the inner lead and the outer lead, and a holding piece in the middle of the outer lead In the method, an outer outer lead is formed by pressing from the holding piece and another lead pattern is formed by etching, or an outer outer lead is formed by etching from the holding piece and another lead pattern is formed by pressing. A method of manufacturing a lead frame excellent in shape retention, characterized by being formed.