JPH04106966A - Formation of lead frame - Google Patents

Abstract

PURPOSE:To bend a lead frame for easy treatment without causing plate peeling in the process of lead bending of J bend type by bending the tip part of the lead three times in the process of bending treatment. CONSTITUTION:In the process of bending the tip of lead 10, first the lead 10 is bent and clamped strongly by die 14 and knockout 16, and punch roller 18 is pressed down along the side of knockout 16 to treat bending of the tip of lead 10. A corner 14b of bending die 14 to be used next is made more protrudent than a corner 14a, and by pressing the corner 14b using the punch roller 18 the lead 10 is more deeply bent into an arc shape. A corner 14c of die 14 to be used next is made more protrudent than the corner 14b, thereby bending the lead 10 into a r shape. These cases all use the roller 18 to press lead 10, thereby being able to protect the film plated on the surface of lead 10 from peeling off and the surface of lead 10 from being scratched.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a lead frame, and particularly to a method for bending a lead into a J shape.

(Prior Art) FIG. 4 is an explanatory diagram showing a conventional method of bending a lead into a J shape. The figure shows the bending position of the lead in each step from the first bending to the fourth bending. 1st bend (A)
Then, bend the tip of the lead 10, bend the lead diagonally at the base of the lead 10 in the second bend (B), bend the lead almost perpendicularly to the mold part 12 in the third bend (C), In the fourth bending (D), it is bent so as to fit into the lower surface of the mold part 12.

FIG. 5 shows another conventional bending method. In this method, the tip portion of the lead is bent in the first bending (A), and the tip of the lead 10 is bent so as to spring upward slightly. The bending process after the second bending is the same as in the above example.

FIG. 6 shows an actual bending method using the bending method shown in FIG. 4 above.

FIG. 6 (a> is the first bending step, in which the lead 10 is compressed by the bending die 14 and the knockout 16, and
A bunch roller 18 bends the tip of the lead 10 at a substantially right angle.

6) is the second bending step, in which the bending die 14 and the knockout 16 support the base of the lead 10, and the punch roller 1
Press down 8 and bend 1-10 at the base position.

FIG. 6(C) shows a third bending process in which the leads, which were opened outward in the second bending, are bent to the inside.

The bending die 14 is provided with four parts that serve as reliefs for the tip of the beam 10.

FIG. 6(d) shows a fourth bending step, in which the lead 10 is bent by the bending die 14 and the knockout 16 so as to be fitted under the mold part 12. The lead 10 is bent by a bending die 14
It is bent to follow the shape of the concave surface.

(Problems to be Solved by the Invention) As described above, in conventional bending, the lead is curled in the fourth bending step, and the lead is bent so as to be embedded in the lower surface of the mold part.

In the fourth bending process, the lead tip is brought into contact with the concave surface of the bending die and bent, but during this bending process, the surface of the lead is rubbed between the bending die and the plating applied to the lead surface may peel off. may occur.

The plating film peeled off from the lead adheres to the lead of the next product during the next bending process, causing problems such as causing an electrical short between the leads.

Therefore, conventionally, the bending die is frequently cleaned to prevent the plating film from adhering to the leads.

In order to prevent the plating film from peeling off, conventional methods have also been used, such as curling the plating film in two steps by reducing the amount of bending, instead of curling the plating film all at once at the fourth bend. However, even this method is not sufficient to eliminate peeling of the plating film because it rubs with the bending die.

Therefore, the present invention has been made to solve the above problems, and its purpose is to perform the bending process without causing problems such as peeling of the plating when performing J-bend type lead bending. The purpose of this invention is to provide a method for molding a lead frame that can be used to form a lead frame.

(Means for solving problems) The present invention has the following configuration to achieve the above object.

That is, in a method for forming a lead frame in which the leads extending outward from the wall surface of the mold part are bent into a J shape and the lead tips are positioned on the lower surface side of the mold part, the first step is to bend the lead ends. The first bending step is characterized in that the final lead tip to be bent is bent into a rounded shape, and then the second and subsequent bending steps are performed to form the lead into a predetermined shape.

(Embodiments) Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing the bending position of the lead 10 in each step when bending is performed by the lead frame forming method according to the present invention.

In the figure, A, +A, , A is the bending position of the lead in the first bending process, B is the second bending process, C is the third bending process, and D is the bending position of the lead in the fourth bending process. Note that the first bending step A,, A2.
A is a step of bending the tip portion of the lead 10, and in the embodiment, the bending is performed in three steps.

Note that the second bending is a step of bending at the base position of the bending beam 10 as in the conventional example described above, a step of bending the third bending beam 10 almost perpendicularly to the mold part 12, and a step of bending the third bending beam 10 almost perpendicularly to the mold part 12.
This is a step of bending the 0 to fit into the lower surface of the mold part 12.

FIG. 2 shows a state in which the lead is actually bent in accordance with each process from the first bending to the fourth bending.

FIGS. 2A, 2B, and 2C correspond to the first bending process described above. In FIG. 2 (a), the lead 10 is bent into the die 14.
The tip portion of the door 10 is bent by pressing it with the knockout 16 and pushing down the bunch roller 18 along the side surface of the knockout 16. In order to bend the lead, the lead 10 is set with its tip portion extending outward from the clamping portion between the knockout 16 and the bending die 14. The corner portion 14a of the bending die 14, which the lower surface of the lead 10 comes into contact with, is formed into an arcuate surface. This results in a lead of 10
The tip is bent into an arc.

FIG. 2(b) is a step of bending the tip of the beam 10 into a deeper arc shape. The corner portion 14b of the bending die 14 used here has an arcuate surface that protrudes more than the corner portion 14a, and is bent further into an arcuate shape by pressing with the punch roller 18.

FIG. 2(c) is a step of bending the tip of the beam 10 into a deeper arc shape. In this bending process, the lead 10
The purpose is to bend the mold part 12 to a curvature approximately equal to the rounded shape that will eventually be curled in order to fit it into the lower surface of the mold part 12.

Therefore, the corner portion 14c of the bending die 14 is provided to protrude further than in the bending step.

In the embodiments shown in FIGS. 2(a), (b), and (c), pressing the lead 10 with the punch roller 18 prevents the plating film on the surface of the lead 10 from peeling off during bending. This prevents the surface from being scratched.

The bending processes shown in FIG. Let's call this the first bend.

FIG. 2(d) shows a bending step corresponding to the second bending in the conventional example, in which the lead 10 is bent at the base position. Since the tip of the lead 10 is curled more than the conventional example in the first bending, the bending die 14
A concave groove 14d is provided so that the tip of the groove does not come into contact with the tip.

FIG. 2(e) corresponds to the third bending in the conventional example. In this bending process, the leads 10 on both sides of the molded part 12 are pressed inward by the punch roller 18 to bend the leads so that the leading ends of the leads are brought closer to the inside. Also in this case, a concave groove 14d for letting the tip of the lead 10 escape is provided in the side wall of the bending die 14.

FIG. 2 (f> corresponds to the fourth bend in the conventional example. By pressing and pressing from above and below with the bending die 14 and the knockout 16, the lead 10 is formed on the lower surface side of the mold part 12.
Bend it so that it holds it. The lead 10 is bent by contacting the concave surface 14e of the bending die 14. In this way, the lead is bent into a predetermined J shape.

According to the bending method of the above embodiment, the tip of the lead 10 is bent in advance into the final curling shape in the first bending, and then the second and subsequent bending processes are performed, so the lead 10 is curled in the fourth bending. The amount of bending required to bend the lead 10 is small, and therefore the lead 10 can be prevented from being rubbed against the bending die 14, and the plating on the lead surface can be prevented from peeling off during the bending process. can. Furthermore, since the plating film is less likely to peel off on the die, there is no need to frequently clean the bending die.

In the above embodiment, the first bending to the third bending is performed using the punch roller 18, but the same can be applied to the case of processing using a punch.

FIG. 3 shows an example of machining using a punch 19. As in the above example, the first bending is performed three times to achieve the final curled shape.

As described above, the purpose of the forming method of the present invention is to reduce the amount of bending of the lead in the fourth bend by performing the curling process of the lead in the first bend, which was conventionally performed in the fourth bend. . Therefore, it is not necessary to perform the bending process until it completely matches the final curled shape in the first bending process, and the effect can be sufficiently exerted by pre-bending the product to a shape that approximates the final curled shape.

Further, in the above embodiment, the lead is bent three times in the first bending process, but the number of times the lead is bent in the first bending process is not particularly limited, and may be set as appropriate. Further, the entire bending process is not limited to the first bending process to the fourth bending process, and can be generally applied to a J-bend type lead bending method.

The present invention has been variously explained above using preferred embodiments, but the present invention is not limited to the above embodiments.
Of course, many modifications can be made without departing from the spirit of the invention.

(Effects of the Invention) According to the method for forming a lead frame according to the present invention, as described above, the lead frame can be formed without peeling of the plating film applied to the lead surface during the bending process. Problems such as electrical shorts between leads can be effectively solved. Furthermore, since the plating film is less likely to peel off and fall onto the bending die during bending, cleaning of the bending die becomes easier.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a lead frame forming method according to the present invention, Fig. 2 is an explanatory diagram showing an example of an actual lead bending method, and Fig. 3 is an explanatory diagram showing another example of a lead bending method. FIGS. 4 and 5 are explanatory views showing a conventional lead forming method, and FIG. 6 is an explanatory view showing an actual lead bending method according to the conventional method. 10... Lead, 12... Mold part, 14-
--Bending die, 14a, 14b, 14c... corner portion, 14cl... concave groove, 14e... concave surface, 16... knockout, 18... bunch roller, 19... punch.

Claims (1)

[Scope of Claims] 1. A method for forming a lead frame in which the leads extending outward from the wall surface of the mold are bent into a J shape, and the leading ends of the leads are positioned on the lower surface side of the mold, comprising: In the first bending process of bending the part, the lead is bent to the rounded shape of the final lead tip to be bent, and then the second and subsequent bending processes are performed to form the lead into a predetermined shape. Characteristic lead frame molding method.