JPS6362296B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for processing a pressed product having grooves.

(Background Art and Problems Therewith) Lead frames for semiconductor devices are mainly formed by press working.

FIG. 4 shows a lead frame 10 used in a resin molded semiconductor device, which has a stage part 14 supported by a stage support bar 12 in the center. A semiconductor element is fixed onto the stage part 14 using a solder alloy, a eutectic alloy, an epoxy adhesive, etc., and these adhesives that fix the semiconductor element are transferred from the stage part 14 to the stage support bar. A V-notch 16 is provided on the stage support bar 12 that reaches both ends of the stage support bar 12 to prevent it from flowing out in the 12 directions.
(V groove) is formed in some cases. That is, when the bonding agent is, for example, a solder alloy, the solder alloy has extremely good wettability depending on the lead frame material, so that the solder alloy may reach the wire bonding point in the middle of the stage support bar 12, and the wire may be attached to the wire bonding point. The V-notch 16 prevents the solder alloy from flowing out to the wire bonding location, since this would make bonding difficult. Note that this flow-out can occur with any bonding agent, and in any case, it becomes an obstacle during wire bonding. When forming the above-mentioned V-notch 16, if it is performed after the stage support bar 12 is punched out, since the stage support bar 12 is narrow, machining distortion of the V-notch 16 may cause the stage support bar 12 to Warpage occurs and stage 14
In order to avoid problems such as inclination of the stage support bar 12 and instability of the position in the height direction, a V-notch is formed in advance in the vicinity of the plate-shaped material, and then the stage support bar 12 is punched out with a press.

This pressing is generally performed from the V-notch 16 side. The side on which the V-notch is formed is naturally the side to which the semiconductor element is fixed, that is, the front side of the product, but in the case of the above-mentioned general manufacturing method, burrs are generated due to press punching on the back side of the product. becomes.

Incidentally, the surface on which the burrs occur is sometimes used as the surface of a product, that is, the surface on which a semiconductor element is mounted. In other words, in the process of sequentially feeding the lead frame and fixing the semiconductor element on the stage section 14, if burrs are generated on the back side, the sliding inside the semiconductor element fixing device will be poor, and the lead frame will not be smooth. This is due to reasons such as inability to carry out transportation.

When the surface on which burrs occur is the surface of the product, the V-notch 16 needs to be on the surface of the product, so the direction in which the V-notch 16 is formed, the stage support bar 12, the leads, etc. The direction is opposite to the direction of press punching. In this case, as described above, if the stage support bar 12 is pressed out from the opposite side after forming the V-notch 16 in the plate-shaped material in advance, the V-notch 16 will be a space, so the V-notch 16 will be cut out. In this case, the punch and die do not engage, and the meat near the end of the V-notch pressed by the punch sag into the V-notch 16 space (Figure 5), forming a relatively large whisker-shaped burr. There is a problem with this. These whisker-like burrs may fly outward and come into contact with the internal lead part, causing a shooting accident.Also, the whisker-like burrs may fall off and adhere to the material surface, causing damage to the lead frame surface during the subsequent pressing process, etc. Further, if it falls off during molding, it may be incorporated into the semiconductor device, causing problems.

(Summary of the Invention) The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a processing method for a pressed product having a groove, which can be formed without generating burrs in the groove. We are here to provide you with
The feature is that in the processing method of a pressed product having a concave groove at least one end of which reaches the press-pull edge, a plate-shaped material is first processed so that the part that will become the press-pull edge is reached by press processing in the subsequent process. In other words, a groove shorter than the required length is formed with a punch, and then the required press working is performed in the opposite direction to the direction in which the punch is driven at the position that will become the edge of the press punch, and then the groove is formed with a punch. A concave groove is formed so as to overlap the groove and reach the press punched edge formed by the above-mentioned press working.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings, taking as an example the case of molding a lead frame.

(1) First step First, as shown in FIG. 1, a first punch 22 is inserted into a predetermined location of the plate-shaped material 20, that is, near the base of the stage support bar that will become a stage support bar in the future. Part 2
4 to form a V-notch. This protrusion 24
has a trapezoidal front view and a triangular cross section. By forming the protrusion 24 in a trapezoidal shape in this way, the material flows smoothly when forming the V-notch, and the plate-like material 20
It is possible to eliminate the bulge of meat on the opposite side. The width of the protrusion 24 (on the front side) is narrower than the width of the stage support bar.

Therefore, the V-notch formed in this first step is narrower than the width of the stage support bar.
Flat portions 26 remain on both sides of the V-notch.

(2) Second Step In this second step, a normal lead frame shape is pressed by a punch from the opposite direction to the first punch 22. 28
The frame indicates the stage support bar left uncut, and the V-notch 30 formed in the first step is within the width of this stage support bar 28, as described above. In this way, since both ends of the V-notch 30 do not reach both ends of the stage support bar 28 that should be left uncut, the entire flat part of the plate-shaped material comes into contact with the cutting edge of the die during press working, which is completely the same as usual. Pressing can be performed, and the meat does not drip into the V-notch space as described above.
The burrs caused by press working are just small burrs that protrude downward to the V-notch side, similar to normal burrs.

(3) Third step In this third step, the protrusion 34 of the second punch 32 overlaps the V notch 30 formed in the first step and the stage support bar 28.
V-notches 36 are formed so as to reach both ends. The height of the protrusion 34 of this second punch 32 is desirably lower than the height of the protrusion 24 of the first punch 22, so that only the flat part 26 of the stage support bar 28 has a relatively shallow height. A V-notch 36 can be formed. Since the V-notch 36 in the third step is shallow and formed only on the flat portion 26, the distortion caused by the formation of the V-notch 36 in the third step is small, and the stage support bar 28 is not warped. It does not lead to deformation.

Although the above embodiments have been explained using a lead frame as an example, the present invention is of course not limited to this, and in products where part or all of the product is press-formed, the lead frame is used as an example. It can be applied to all products in which grooves such as V-notches are formed.

(Effects of the Invention) As described above, according to the present invention, first, a concave groove that does not reach the part that should become the press punched edge is formed,
Since press punching is then carried out, the edges of the concave grooves are not scratched during the press punching process, and the conventional problem of the meat sagging into the concave groove spaces and creating whisker-like burrs is solved. Ru.

In order to create a groove that reaches the press-cut edge, it is sufficient to newly form a groove in a narrow range between the groove edge and the press-cut edge, which can reduce distortion and improve the quality of the product. It does not cause deformation such as warping.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the first step, FIG. 2 is an explanatory diagram of the second step, and FIG. 3 is an explanatory diagram of the third step. FIG. 4 shows a plan view of the lead frame. FIG. 5 is an explanatory view showing a state in which the end of the V-notch sags into the V-notch when forming a conventional V-notch. 10...Lead frame, 12...Stage support bar, 14...Stage section, 16...V notch, 2
0...Plate material, 22...Punch, 24...Protrusion, 26
...Flat part, 28...Stage support bar, 30...
V notch, 32... punch, 34... protrusion, 36... V
Notsuchi.

Claims (1)

[Scope of Claims] 1. In a method for processing a pressed product having a concave groove at least one end of which reaches a press-pull edge, a plate-shaped material is first processed to reach a portion that will become a press-pull edge through subsequent press processing. In other words, a groove with a shorter length than the required length is formed by punching, and then at the position that will become the press punched edge,
A necessary press process is performed in the opposite direction to the direction in which the punch is driven, and then a groove is formed so as to overlap the groove and reach the punched edge formed by the press process. A method for processing pressed products with characteristic concave grooves.