JPS62152130A - Mold formation and lead frame applicable thereto - Google Patents

Abstract

PURPOSE:To prevent any no resin filled part as well as any notch on package from occurring by a method wherein a diestage of lead frame is arranged in a cavity inclined by + or -45 deg. to the runner to be connected to a gate orthogonal to the runner. CONSTITUTION:A gate 13 of bottom force 11 is formed to extend from a runner 15 almost orthogonal thereto. One corner of a lead frame 21 comprising a diestage 22 four sides of which are arranged with leads 23 is connected to an end of the gate 13. Each side of diestage 22 is arranged in a cavity inclined by + or -45 deg. to the runner 15 to be resin-injected from the gate 13 for mold formation. The resin flow is improved by changing its direction only by one degree. Besides, when a package is lifted along the runner 15 to isolate the package from the resin in gate 13, the cut off line corresponds with the boundary line 16. Through these procedures, any no resin filled part as well as any notch or protrusion on package can be prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The die stage of a lead frame for a plastic package having leads on four sides is tilted by 45 degrees with respect to the conventional example, thereby improving the incident angle of the gate.

[Industrial application field]

The present invention relates to a molding method, and more specifically, the present invention relates to a molding method, and more specifically, a plastic package with leads arranged on four sides is made of plastic with a lead frame having a die stage angled by 45 degrees with respect to a conventional die stage. The present invention relates to a method of making a seal and a lead frame.

[Conventional technology]

A conventional method for molding a plastic package in which leads are arranged on both sides of the package in the longitudinal direction will be explained with reference to the plan view of FIG. The frame 31 is arranged so that its die stage fits inside the cavity 12, the upper mold (not shown) is closed, resin is injected from the gate 13 to make a mold resin corresponding to the shape of the cavity 12, and the lead frame 31 is inserted from both sides of the mold resin. A plastic package is formed from which the leads 32 extend.

Recently, a plastic package has been developed, as shown in the plan view of Figure 4, in which leads are arranged on the four sides of the package.
In FIG. 4, 20 is a pan cage, and 23 is a lead extending from the four sides of the package 20.

When making such a package, it is not possible to arrange the conventional gate 13 as shown by the dotted line, so the gate 13 is placed radially from one of the four corners of the package as shown by the solid line in the figure. It must be installed in the correct position.

The lower die provided with the gate as described above is schematically shown in the plan view of FIG. 5, in which 14 is a cull, 15 is a runner, and 21 is a lead frame. A part of the lower mold shown in FIG. 5 is shown in detail in the plan view of FIG. 6, and a cross-sectional view taken along line A-A in FIG. 6 with the upper mold 18 closed is shown in FIG. .

Note that the conventionally used lead frame 21 is shown in the plan view of FIG. 9, and two sides of the die stage 22 extend parallel to both sides of the lead frame, and the other two sides extend in the lateral direction of both sides of the lead frame. Take composition.

[Problem that the invention seeks to solve]

At the stage where the resin encapsulation is completed, the resin in the runner 15, the resin in the gate 13, and the molded resin in the package 20 are integrated (i.e., connected) as shown by the sanded area in the plan view of FIG. Therefore, when the temperature of the resin drops to a predetermined temperature, the molded resin of the pan cage 20 must be separated from the resin of the other integrated parts.

To do this, a lead frame integrated with the molded resin is raised parallel to the runner 15 and the resin is folded into pieces. At that time, the IAJ resin in the gate 13 and the mold resin (which is the package itself)
The separation must be made along the boundary line 16 between the pancage 20 and the gate 13 shown in the plan view of the figure, but the separation due to the rise of the lead frame occurs along a line parallel to the runner 15. In reality, the cutting line often occurs along the line labeled 17 in FIG. The reason is that the cutting line 17 tends to be parallel to the runner, but the boundary line 16 described above is parallel to the runner 1.
This is because it is located at a certain angle of 1 to 5.

n: When the resin separation described in 1 is performed along the cutting line 17, the finished package 20 may have a notch 41 and a protrusion 42 to which resin is adhered, as shown in FIG. If the notch 41 exists, external moisture will enter through it, degrading the moisture resistance of the package, and if the protrusion 42 is formed near the corner of the package, the mechanical strength of the leads located near it will deteriorate. kW, and furthermore, there is a problem that a crank occurs near the notch 41, deteriorating the strength and moisture resistance of the package.

If the protrusion 42 is attached to the package, the socket etc. may get caught when the pan cage is mounted, and when the package is automatically handled by an automatic handler, the auto handler may come into contact with the protrusion 42 and cause malfunction. be.

Furthermore, as shown by arrow I in Figure 5, the flow of the resin changes during resin injection, which may impact the wires connecting the electrodes and leads of the chip in the pancage, or cause damage to the resin. There is also the problem that bubbles are generated and resin-unfilled areas are created within the package, which deteriorates the pressure resistance and moisture resistance of the package.

The present invention was created with these points in mind, and it improves the flow of resin in the molding of a plastic package in which leads are arranged on the 4th side, and prevents notches, cracks, and cracks in the package near the gate. It is an object of the present invention to provide a mold forming method that prevents the above problems.

[Means for solving problems]

FIG. 1 is a plan view of an embodiment of the present invention.

Referring to FIG. 1, the gate 13 of the lower mold is connected to the runner 15.
In molding using such a mold, the die stage 22
The lead frame 21 has leads 23 arranged on four sides of the lead frame 21. One corner 24 of the lead frame 21 is located at the end of the gate 13, and each side of the die stage 22 of the lead frame 21 is inclined at ±45 degrees with respect to the runner 12. Then, the resin is placed in the cavity 12, resin is injected, and molded.

[Effect]

In the above method, since the flow of resin only changes direction once, shadows on conventional wires and unfilled areas are prevented, and when separating the pan cage and the resin in the gate, the package When raised along the runner as in the past, the cutting line of the resin coincides with the boundary line 16 between the package and the resin in the gate, so that the package can be separated cleanly without any notches or protrusions.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

In the method of the present invention, a lead frame 21 shown in FIGS. 2(al) and (bl) is used.

First, in the lead frame 21 shown in FIG. 2(a), the four sides of the die stage 22 are inclined at approximately ±45 degrees with respect to both sides of the lead frame 21. The lead frame 21 is formed by mechanical punching or etching like the conventional lead frame. However, the arrangement of the die stage 22 of the lead frame 21 and the leads 23 extending from the die stage 22 are different from those shown in FIGS.
As can be understood from the contrast in the figures, the structure is extended by approximately 45° compared to the conventional example.

The above-mentioned lead frame 21 is inserted into the lower mold 11 so that the die stage 22 is accommodated in the cavity 12 as shown in FIG.
Place it on top. The cavity 12 of the lower mold 11 is different from the conventional example shown in FIG. is inclined at approximately 45 degrees with respect to the extending direction of the runner, so when the lead frame is placed on the lower die 11, the two sides of the die stage 22 that form the corner 24 are also tilted at an angle of 45 degrees with respect to the direction in which the runner extends, unlike the conventional example.
2 ±45° head.

When such a lower die and lead frame 21 are used, the boundary line 16 between the gate 13 and the package molded in the cavity becomes almost parallel to the runner 12 as shown in FIG. When the package is raised to separate the resin, the resin separation line and the boundary line 14 coincide, and the resin is neatly separated, preventing cutouts or protrusions from remaining on the package as in the conventional example. Prevented.

FIG. 2(b) is a modification of the lead frame shown in FIG. The die stage 22 and leads 23 are arranged at an angle of approximately 45° compared to the conventional example shown in Fig. 9, which is similar to the example shown in Fig. 2 (al). The manufacturing method is also exactly the same.

When using this modified lead frame, the gate 13 of the lower mold 11 is located at the location shown by the dotted line in the same figure, and the gate 13 of the lower mold 11 is located at the position shown by the dotted line in the same figure. Twice as many pancakes can be formed.

〔Effect of the invention〕

As described above, according to the present invention, in the manufacture of a package having a structure in which the reeds protrude from four sides, the flow of resin during resin injection is improved, and the adverse effects on the wires are reduced.
It is possible to reduce unfilled resin, etc., and prevent notches, cracks, etc. in the package near the gate, and as a result, there is an effect of improving the yield of manufacturing the Plastinokupa 7 cage.

[Brief explanation of drawings]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a plan view of a lead frame used in the pan cage shown in FIG. Figure 3 is a plan view of the lower mold of a conventional mold, Figure 4 is a plan view of the package, Figure 5 is a plan view of the lower mold of a conventional mold, and Figure 6 is the lower mold of Figure 5. A plan view showing a part of FIG. 7, A of FIG.
-A sectional view taken along line A, FIG. 8 is a plan view showing problems in the conventional example, and FIG. 9 is a plan view of the conventional lead frame. 1 to 8, 11 is a lower mold, 12 is a runner, 13 is a gate, 14 is a cull, 15 is a runner, 16 is a boundary line, 17 is a cutting line, 18 is an upper mold, 20 is a package, 21 22 is a lead frame, 22 is a die stage, 23 is a lead, 24 is a corner, 25 is an unused portion of the lead frame, 31 is a lead frame, 32 is a lead, 41 is a notch, and 42 is a protrusion. Agent Patent attorney: Hajime Kuki Agent: Yoshi Osuga 2 Invention 11 Comprehensive view Figure 1 Invention light 1 Diagonal raft concave Figure 2 Yushi 41 Color No. F (Color m Figure 4 Machai I-Ren Town Prisoner Figure 5 and Shooting Lee ('/,) Tne T Section District Figure 6 Procedural Amendment (Method) 2. Name of the invention ゛ Mold molding Relationship between the method, the lead frame 3 used therein, and the case of the person making the amendment Patent applicant Address: 1015 Kamiodanaka, Nakahara-ku, Yozaki-shi, Kanagawa Prefecture Name: Fujitsu Corporation 4, Agent address: 1-chome Shinjuku, Shinjuku-ku, Tokyo No. 31 3'-808 March 5, 1986 (Shipping date: March 25, 1986)
6. Target of correction
Exhibition-1@1 +! ]Figure 3 *'li4? l call koma Σ Fig. 4 Shōkata Reirai A It! i-! D Feng] No. 60 g=i-I sequence if'ria Fig. 7 □

Claims (3)

[Claims] (1) In a method of forming a plastic package (20) with leads (23) extending from four sides, the four sides are connected to a gate (13) extending substantially perpendicularly to the runner (15). A die stage (22) is formed at an angle of ±45° with respect to both sides of the lead frame (21) in a cavity (12) of a lower die (11) of the mold die which is inclined at approximately ±45° with respect to the extending direction of the lead frame (21). Close the upper mold (18) and remove the runner (15) from the cull (14).
), a mold forming method characterized by injecting resin through a gate (13). (2) Package with leads (23) extending from four sides (
20), the four sides of the die stage (22) arranged in one row in the longitudinal direction of the lead frame (21) are approximately ±45 degrees with respect to both sides of the lead frame (21). A lead frame which is tilted at an angle of 1.degree. and has leads (23) arranged substantially perpendicularly to each side of the die stage (22). (3) The lead frame according to claim 2, wherein the die stages (22) are arranged in two rows in the longitudinal direction of the lead frame (21) in alternating vertical positions.