JP3345822B2 - Semiconductor device lead processing method and processing die - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing a lead of a semiconductor device and a processing die thereof, and more particularly to a method of processing a lead after packaging a flat IC and a processing die thereof.

[0002]

2. Description of the Related Art In the manufacture of a semiconductor device, for example, the leads of a package immediately after being molded are formed such that leads arranged substantially from the center of the mold project outward toward the outside by a length corresponding to a bending length. Then, the lead is bent so that it can be easily mounted to complete a flat IC, for example. This type of lead bending corresponds to a forming step in a later step of a step called a T / F (trim and form) step. For example, literature (single book); VLSI packaging technology (see below) ), Published by Nikkei BP, May 31, 1993, pp. 47-50
There is a technical commentary on it.

Conventionally, this type of lead bending has been performed using a mold. The mold is composed of an upper mold and a lower mold, and the upper mold has a bending punch for bending the lead, a presser piece for holding the lead, and a spring for pressing this presser piece, and the lower mold has the above-mentioned lead. A bending die is provided for setting the cut package to the deployed length of bending. Here, the upper pressing piece has a flat pressing surface of the lead and has a structure which can be operated up and down. The lower bending die receives the lead and sets the package.

[0004] The processing steps of the lead using this mold will be described below. First, the package is set on a bending die, and then the upper mold is lowered. Then, after the lead near the package is clamped between the presser and the bending die, when the lead is further lowered, the spring pressing the presser is compressed, and the lead is strongly supported. Next, in this state, the bending punch also descends, and the leading end side of the lead is bent by the pressure to complete the flat type IC as shown in FIG.
In FIG. 4, reference numeral 1 denotes a mold package;
Reference numeral 2 denotes an IC input / output lead.

[0005]

However, the molded package has a slight bow-like warpage. Therefore, as shown in FIG. 3, the plurality of leads 2 led out from the mold package 1 are arranged in a warped manner. When the leads 2 of such a mold package 1 are bent by the above-described conventional mold, the arrangement of the tips of the leads 2 becomes an arc shape corresponding to the warpage of the mold package 1 as shown in FIG. . This phenomenon is well known, and when a semiconductor device having a warped lead tip is mounted on, for example, a wiring board by solder, the solder connection to the board becomes unstable and the reliability of mounting is significantly impaired. For this reason, there has been a problem that the arrangement of the bent lead ends must be corrected with high precision and uniform flatness before mounting. And, of course, this correction process has caused a problem that the cost is increased.

[0006]

According to the present invention, there is provided a semiconductor device lead processing method comprising: an upper die having a bending punch having a pressing piece operating inside and a spring pressing the pressing piece; In a lead processing method for a semiconductor device in which a lead is pressed and bent by using a lower die having a bending die for setting a mold package having a bent lead, the lead at the bottom of the warpage of the lead row is restored by springback. The bending die that sets the package by lifting the lead with a step that is bent to an angle that is bent at an angle larger than the inclination angle at which the lead that is the high part of the warpage of the lead row is bent due to the step between the lead part and the bending die surface Near the package by bending it from the lead-out section to an angle corresponding to the warpage of each lead row using a holding piece having a projected inclined surface After clamping the lead, in which bend the distal end portion of the lead.

Further, a lead processing die for a semiconductor device according to the present invention is led out in the plane direction from an upper die comprising a presser piece which moves inside and a bending punch having a spring which presses this presser piece. A lower die mainly composed of a bending die for setting a mold package having leads, a lead processing die of a semiconductor device for bending a lead by pressing a lead with an upper die and a lower die, and The holding surface for holding the lead is inclined at an angle larger than the inclination angle that can be bent by the step between the lead lead-out part and the bending die surface with respect to the projecting surface of the opposite bending die, and the molding die is molded. This is a bent die structure in which the lowest surface of the lead floats above the projection surface when the package is set.

[0008]

According to the lead processing method of the present invention, a bending die for setting a package by lifting a lead with a step at which a lead serving as a bottom of a warp of a lead row is bent to an angle to be restored by springback, and a high warp of the lead row are provided. The lead to be a part is a holding piece having a protruding inclined surface set to an angle larger than the inclination angle bent by the step between the lead part and the bending die surface, and the lead part has an angle corresponding to the warpage of each lead row from the lead part After the lead is bent, the lead near the package is bent, and then the end of the lead is bent. Therefore, even if the lead row before processing is warped, the arrangement of the end is uniform and flat.

In the lead processing die of the present invention, an upper die comprising a pressing piece and a bending punch having a spring for pressing the pressing piece, and a mold package having leads led out in the surface direction are set. A die for forming a lead of a semiconductor device, which comprises a lower die having a bending die as a main body and presses and bends a lead with an upper die and a lower die, and has a pressing surface for holding a lead of a pressing piece. The structure is designed to be inclined at an angle larger than the inclination angle that can be bent by the step between the lead lead-out part and the bending die surface with respect to the projecting surface of the opposing bending die. Since the bending die structure has the lowest surface floating above the protruding surface, if this is used for lead processing, a flat row of leads at the tip can be obtained.

[0010]

FIG. 1 is a process diagram showing a procedure for lead processing of a mold package according to an embodiment of the present invention. The essential structure of the lead processing apparatus will be explained as needed while explaining the process status in the order of the process diagrams of FIGS. 1 (a), 1 (b) and 1 (c). In FIG. 1, a die used in a lead processing method of the present invention is a bending punch 1 for bending a lead into an upper die 11.
2, 12a, a holding piece 13 for holding the lead, a spring 14 for pressing the holding piece 13, and a lower die 15 having a bending die 16 for setting a mold package 17 from which the lead 18 is led out. Here, the upper presser piece 13 has a light presser surface 13a of the lead, and is operable. When the mold package 17 is set, the lower die 16 is set with the leads 18 floating by a predetermined amount (described later) from the surface of the projection 16a of the bending die 16.
The surface of the protrusion 16a just described is a horizontal surface.

Next, a description will be given of a step of processing a lead of a flat type IC using a mold (see FIG. 1) according to the present invention. First,
In FIG. 1A, the mold package 17 in which the lead 18 has been cut to the developed length of the bend is set on the bending die 16, and the upper die 11 is lowered. Then, as a result of this lowering, as shown in FIG. 1B, the lead 18 led out from the mold package 17 is bent from the lead-out portion (root portion) by the pressing surface 13a of the pressing piece 13. Then, the lead 18 near the package 17 is clamped by the pressing surface 13a and the protrusion 16a. In this state, when it is further lowered, as shown in FIG. 1 (c), the spring 14 pressing the pressing piece 13 is compressed,
The lead 18 clamped by the spring force is further strongly supported. On the other hand, the bending punches 12 and 12a also descend, and the tip of the lead 18 is pressed and bent.

In the bending of the lead, the lead is bent from the lead-out portion by the holding surface 13a of the holding piece 13 while being floated from the upper surface of the projection 16a of the bending die 16. The step is set so that the bent lead at the angle (elastic limit) at which the bottoms of the warped rows return by springback is formed. Further, the inclination of the pressing surface 13a of the pressing piece 13 is slightly larger than the inclination angle at which the lead, which is the high portion of the warped arrangement, is bent by the step between the lead portion and the bending die surface. In this manner, each lead 18 led out from the mold package 17 is bent at an angle corresponding to the warp from the lead portion. Then, all the bent portions of the bent lead are spring-backed to return to their natural state when the external force by the mold is removed, that is, when the upper mold is sufficiently raised.

In this case, since all the leads are bent in the same manner except for the bent portion near the lead-out portion of the package, all the leads have the same bent shape even after springback. On the other hand, the lead of the bent part of the lead-out part also springs back, but the other lead, which is the bottom part of the warped line, is bent at an angle (more than the springback) corresponding to each warp, so after springback, A bent shape corresponding to each warp is formed. By the formed bending, the warpage of the arrangement corresponding to each lead is corrected, and even if the package is warped, the arrangement of the tips of the bent leads is uniform as shown in FIG. It becomes a flat flat surface. Therefore, the reliability at the time of mounting is improved, and the above-described problem can be efficiently achieved.

In the above-described embodiment, the case where the present invention is applied to bending of a lead of a flat type IC having leads led out in two directions from opposite sides of the mold package has been described as an example. If a punch, an inclined portion of a holding piece and a bending die are arranged, the present invention can be applied to bending of a lead of a flat type IC having leads led out in four directions from a mold package.

[0015]

As described above in detail, according to the present invention, a lead row in which the arrangement of leads derived from a mold package is warped is formed at an angle corresponding to the warp of each lead in the vicinity of the lead part. After bending and holding the holding piece of the processing machine and the bending die, the tip of the lead is bent using a bending punch. Therefore, even if the lead row is warped due to the warpage of the mold package, the tips are aligned. Was formed as a uniform flat portion, and the object of the present invention could be achieved. By achieving this task, a great effect of securing the reliability in mounting the mold package was obtained.

[Brief description of the drawings]

FIG. 1 is a process chart showing a lead processing procedure according to an embodiment of the present invention.

FIG. 2 is a side view showing a flat surface of a lead tip after lead processing according to the present invention.

FIG. 3 is a side view showing a state of a conventional mold package before lead processing.

FIG. 4 is a side view showing that the arrangement of the tips after bending from the state of FIG. 3 with a conventional mold is arcuate.

FIG. 5 is a perspective view showing a general conventional flat IC package.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Upper die 12, 12a Bending punch 13 Holding piece 13a Holding surface 14 Spring 15 Lower die 16 Bending die 16a Projection 1,17 Mold package 2,18 lead

Claims (2)

(57) [Claims] 1. An upper die having a bending punch having a pressing piece operating inside and a spring pressing the pressing piece, and a lower die having a bending die for setting a mold package having leads extending in a plane direction. A lead forming method for a semiconductor device, wherein the lead is bent at an angle at which the lead serving as a bottom of the warpage of the lead row is restored by springback. The bending die, and the lead, which is the high part of the warpage of the lead row, has a projecting inclined surface set at an angle larger than the inclination angle bent by the step between the lead portion and the bending die surface. Using the holding piece, the lead-out section is bent at an angle corresponding to the warpage of each of the lead rows, and the lead near the package is bent. After clamping the de, lead processing method of a semiconductor device characterized by bending the leading end portion of the lead. 2. A bending die for setting a mold package having a presser piece that moves inside and a bending punch having a spring that presses the presser piece, and a mold package having leads extending in the surface direction. A lead processing die for a semiconductor device configured to include a lower die and press and bend the lead with the upper die and the lower die, wherein a pressing surface for performing lead pressing of the pressing piece is opposed to the pressing surface. The lead-out portion and the bent portion of the lead with respect to the projecting surface of the bending die
Angle larger than the inclination angle that is bent by the step with the vertical die surface
The bending die structure wherein the lowest surface of the lead floats above the protruding surface when the mold package is set on the bending die. Mold.