JPH02140963A - Lead frame and separating method for gate using the lead frame - Google Patents

Abstract

PURPOSE:To separate a gate by a small force without remainder of burr by providing a protrusion protruding toward a downward direction on the lower face of a lead frame, and forming the outer wall of the protrusion in a sharp conical shape. CONSTITUTION:A gate 14 is formed on the lower face of a lead frame 10, and the connecting part 24 with a package 12 is formed in a slender pinch structure. A protrusion 18 is formed substantially in a conical shape protruding to the lower face of the frame 10. When a force B of a direction separating from the frame 10 is applied to the gate 14, the gate 14 is prevented from adhering to the lower face of the frame 10 due to the protrusion 18, and the gate 14 can be easily separated by a small force from the frame 10. Accordingly, the force B which operates on the gate 14 is concentrated to be operated at the part 24 of the pinch structure of the gate 14 to the package 12. Thus, the gate 14 is bent at the part 24 to separate the package 12 from the gate 14. In this manner, the gate 14 can be separated by the small force without remainder of burr.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lead frame and a gate isolation method using this lead frame.

(Prior Art) A conventional gate isolation method will be explained with reference to FIG.

FIG. 4 shows a lead frame 102 molded with resin to form a package portion 100. As shown in FIG.

In order to separate scraps such as the gate 104 from the lead frame 10, the pan cage portion 10 is mounted on a support means (not shown).
0 and/or the lead frame 10 and apply a force to the gate 104 as indicated by the arrow X, the connecting portion 106 between the gate 104 and the package portion 100 has a pinch structure, and the gate 10 separates from the lead frame 102. In this case, the gate 104 can be separated from the package part 100 at the connection part 106.

(Problems to be Solved by the Invention) However, the above conventional gate isolation method has the following problems.

After finishing the resin mold 1. When the resin solidifies, the gate 104
is adhered at the surface contact portion to the lead frame 102. If the adhesive strength is strong, the force X required to separate the gate 104 from the lead frame 102 needs to be large.

Further, if the adhesive force of the gate 104 is strong, when the gate 104 is separated from the lead frame 102, the gate 104 will break at a place where the adhesive force is weak, and the gate 104 will not be separated at the connecting portion 106 formed in a pinch structure. However, there is a problem in that burr remains on the package portion 100 and lead frame 102, requiring additional burr removal work.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a lead frame capable of separating gates with a small force without leaving a gap, and a method of separating gates using this lead frame.

(Means for solving problems) In order to solve the above problems, the present invention has the following configuration.

That is, the lead frame is characterized in that a protrusion is formed on the gate side surface of the portion of the lead frame corresponding to the gate, and the protrusion protrudes so that the tip thereof is tapered. A protrusion is formed on the gate side surface of the portion corresponding to the gate, and the lead frame is placed in a molding die and resin molded, and then the protrusion protrudes from the gate. It is characterized by separating the gate by applying force in the direction.

(effect) The effect will be explained.

After resin molding, the resin contracts as it solidifies.

At this time, since the shrinkage rate of the resin is greater than the shrinkage rate of the lead frame, the resin in the gate part slips along the outer wall surface of the tapered protrusion, preventing it from adhering to the lead frame. However, when a force is applied in the direction in which the protrusion protrudes, the gate can be easily separated without leaving a gap.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, a lead frame 10 suitable for use in the gate separation method according to the present invention will be described with reference to FIG. Third
In the figure, after the package part 12... is molded with resin,
Lead frame 1 with gate 14 still connected
Indicates 0. A protrusion (shown as 18 in FIG. 1 or 2) is formed on the surface (lower surface) of the site rail 16 of the lead frame 10 on which the gates 14 are formed. In this protrusion work 8, a protrusion 18 is formed on the lower surface by forming recesses 20 on the upper surface of the sight rail 16. The recesses 20 may be formed by, for example, using a punch or the like.

Next, the protrusion 18 will be explained with reference to FIG.

The protrusion 18 protrudes downward from the lower surface of the lead frame 10, and the outer wall surface 22 of the protrusion 18 is tapered. In the case of this embodiment, the protrusion 18 has a substantially conical shape, but it may also have a pyramidal shape, a truncated cone shape, or a truncated pyramid shape. Note that the size (diameter) is preferably set to be approximately the width of the gate 14.

Next, a method for separating the gate after resin molding using the lead frame 10 described above will be explained with reference to FIG. 1.

FIG. 1 shows a cross-sectional view of a lead frame 10 in which a package portion 12 is formed by resin molding.

The gate 14 is formed on the lower surface of the lead frame 10, and the connection part 24 with the package part 12 is formed in a thin pinch structure. As described above, the protrusion 18 is formed in a substantially conical shape that protrudes from the lower surface of the lead frame 10. The package portion 12 and/or the lead frame 10 are supported by suitable support means (not shown), and a force is applied to the gate 14 in a direction as shown by arrow B to separate it from the lead frame 10. Then, since the protrusion 18 prevents the gate 14 from adhering to the lower surface of the lead frame, the gate 14 easily separates from the lead frame 10 with a small force. As a result, the force B acting on the gate 14 is
Since the action is concentrated on the connection portion 24 formed in the pinch structure between the gate 14 and the package portion 12, the connection portion 2
At step 4, the gate 14 is broken and the package portion 12 and the gate 14 are separated. When the gate 14 is separated at the connecting portion 24, no debris remains on the puff cage portion 12 or the lead frame 10.

Here, the protrusion 18 is provided protruding from the gate 14 side of the lead frame 10, so that the lead frame 18 of the gate 14
Prevention of adhesion will be explained with reference to FIG.

For example, the metal forming the lead frame 10 has a coefficient of thermal expansion of 4.2X 10-'/'e, while the coefficient of thermal expansion of the resin used for the resin mold is 20X 10-6.
/'C, and the resin has a considerably larger value. Therefore, after resin molding is completed, the shrinkage rate when the resin solidifies is considerably thicker for the gate 14 made of resin than for the lead frame 10.

Therefore, as shown in FIG. 2 (an enlarged view of part A in FIG. 1), after the gate 14 solidifies, the gate 14
tries to contract at a higher shrinkage rate than the lead frame 10, so the force P of the shrinkage is applied to the outer wall surface 2 of the protrusion 18.
It acts on 2. However, since the outer wall surface 22 of the protrusion 18 is formed as a slope, a component force represented by F (F=P cos θ) acts on the resin surface in contact with the outer wall surface 22, and the lead of the gate 14 Slippage occurs in the portion that is in surface contact with the frame 10. Due to this slipping, the sliding surface hardly adheres to the facing surface of the lead frame 10, and the gate 14 is connected to the package portion 1 at the connecting portion 24.
It will be in a state where it is only connected to 2. Therefore, it is considered that in order to separate the gate 14, it is sufficient to simply apply a force that separates the connecting portion 24. Further, the warping of the lead frame 10 caused by the contraction of the resin does not occur because the protrusion 18 is plastically deformed, and when viewed relatively, only the resin contracts, so that the resin near the protrusion 8 is not strained. It becomes the state that occurred. It is believed that this strain also promotes separation between the lead frame 10 and the resin. The protrusion 18 may have various shapes as described above, but in short, it has a slope that causes the resin in the portion that was in contact with the lead frame 10 to slip and/or distort when the gate 14 contracts. It's good to have it.

Note that if the protrusions 18 are provided at the early stage of forming the lead frame 10, it is possible to eliminate the influence of distortion when forming the protrusions 18 on the lead frame 10.

Various preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-mentioned embodiments, and can be applied not only to gates but also to scrap removal from surfaces such as runners. Of course, many other modifications may be made without departing from the spirit of the invention.

(Effects of the Invention) By using the lead frame and the gate separation method using this lead frame according to the present invention, it is possible to prevent scraps such as the gate from adhering to the lead frame during solidification of the resin. It becomes possible to separate the gates with a small force. Since the gate can be separated with a small force, the energy consumption of mechanical equipment is also low, making it economical.

In addition, if the connection part of the gate to the puff cage part is made into a pinch structure, it will prevent the gate from adhering to the lead frame and will also ensure that the gate can be separated from the connection part, so there will be no residual dust. This has great effects, such as eliminating the need for troublesome deburring work.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view showing the state after resin molding to explain the gate separation method according to the present invention, Fig. 2 is an enlarged view of section A in Fig. 1, and Fig. 3 is a partial cross-sectional view showing the state after resin molding. FIG. 4 is a perspective view of the lead frame showing the state, and a partial sectional view showing the conventional gate separation method. 10... Lead frame, 14... Gate,
18... Protrusion.

Claims (1)

[Scope of Claims] 1. A lead frame characterized in that a protrusion is formed on the gate side surface of a portion of the lead frame corresponding to the gate so as to protrude so as to have a tapered tip. 2. Form a protruding part on the gate side surface of the part of the lead frame corresponding to the gate so that the tip thereof is tapered, place the lead frame in a mold and perform resin molding, and then apply the resin to the gate. A method for separating a gate, comprising separating the gate by applying force in a direction in which the protrusion protrudes.