JPS6157319A - Resin molding method of electronic parts - Google Patents

Abstract

PURPOSE:To prevent generation of burrs on a lead part, by so constituting a lead frame that the other cavity is provided on a position corresponding to a lead part of the outside of the lead frame and resin is poured within a cavity provided corresponding to a principal part. CONSTITUTION:A surface side and a back side of a lead frame 13 are provided respectively with a top force 11 and a bottom force 12 and the dimensions of a cavity 21 in a widthward and heightward directions are made smaller than those of cavities 14 positioned on both sides of the cavity 21. A tab part 20 of the lead frame 13 is provided with a semiconductor pellet and electric connection is applied to a space between an electrode provided on the semiconductor pellet and lead part of the outside by a wire. Contact bonding of the top force 11 and bottom force 12 is performed respectively from the surface side and th back side of the lead frame 13 under such condition, which is made to concentrate by pouring molding resin within the cavity 14 from a runner 16 and generation of burrs is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a resin molding method for electronic components such as semiconductor elements.

[Background Art] As shown in FIG. 1, the conventional resin molding method for semiconductor devices involves fixing one mold, such as the lower mold 2, and lifting the other mold, such as the upper mold 1, with a press (not shown), and then molding the lead frame. 3 is loaded onto a lower mold guide pin (not shown), and the upper mold 1 is lowered and tightened. As a result, as shown in FIG. 2, both the front and back surfaces of the lead frame 3 form a cavity 4. Date 5. Upper mold 1 except for runner 6. It was tightened with the lower mold 2, and in this state, mold resin was injected into the cavity 4.

However, in such conventional semiconductor molding methods, the upper mold 1. Depending on the contact (parallelism) and tightening of the lower die 2, an extremely thin burr 9 (usually less than 20 um) may be formed on the outside of the dam 7, that is, on the external lead part 8, as shown in the figure m2. Because it is thin, it is difficult to remove it, and because it is thin, it is difficult to detect the presence or absence of the burr 9. Therefore, during assembly, there was a problem in that solder did not adhere to the external lead portion.

In addition, one way to take this kind of Paris
It is known from Publication No. 777.

[Object of the Invention] An object of the present invention is to provide a new mold grouping method that does not cause thin mold burrs on the external lead portion.

[Summary of the Invention] The basic groove bottom of the present invention to achieve such an object is as follows:
A resin molding method for electronic components, in which a cavity is provided between an upper mold and a lower mold corresponding to the main part of a lead frame, and resin is injected into the cavity to mold the electronic component, the dam part of the lead frame being molded. The lead frame is held down by an upper mold and a lower mold, and another cavity is provided at a location corresponding to the external lead part of the lead frame, and resin is injected into the cavity provided to correspond to the main part. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention, which is a characteristic resin molding method for electronic components, will be described below with reference to the accompanying drawings.

[Example] FIG. 3 is a plan view of a molding device of the present invention, and the cavity 14 is formed to correspond to the main part of the lead frame 13 including the tab 20 and the internal lead part 17.
A runner 16 is connected through a gate 15 through which mold resin can be supplied. Further, a cavity 21 is formed next to the cavity 14 (1) so as to correspond to the external lead portion 18 of the lead frame 13. As is clear from this figure, the dam portion 7 of the lead frame 13 is pressed down by the upper mold and the lower mold.

FIG. 4 is a longitudinal cross-sectional view taken along the line A-A in FIG. 12, the width and height dimensions of the cavity 21 are smaller than those of the cavities 14 located on both sides of the cavity 21, but since this part only needs space, both the inside and height are smaller than the cavities 14. It can be large. Then, the upper mold 11 and the lower mold 12 have spaces of the same size, forming one cavity 21.
It consists of Although not shown, a semiconductor pellet is attached to the tab portion 20 of the lead frame 13, and an electrical connection is made between the electrode provided on the semiconductor pellet and the external lead portion by a wire.

In this state, if the upper mold 11 is pressed from the front side of the lead frame 13 and the lower mold 12 is pressed from the back side, and mold resin is injected into the cavity 14 through the gate 15 through the runner 16, this resin will be poured into the cavity 14. fill the void.

In particular, when one cavity 21 is provided between the dams as shown in Fig. 3 and f54, the upper mold The clamping force of the lower die is concentrated on the dam part, which has the effect of preventing the occurrence of flashing.

Even if it passes through the opening 4 in the plates between the upper mold and the lower mold, it will leak into the cavity 21, and as shown in FIG. A burr 27 is formed. Therefore, the burr 27 on the molding formed as shown in Fig. 5 shows the BB cross section in Fig. ff55! @6 From the state shown in Figure (a), that is, the state in which the external lead portion 18 is at 7 rats, to the state shown in Figure (b), the bending die (lower die) 31 and the bending die (upper die) 32 are forcibly removed. During bending, most of it is automatically removed by the stress caused by the bifold molds 31, 32 and by the mechanical impact applied when cutting the dam (not shown).

[Effect 1] As is clear from the above explanation, according to the present invention, a common cavity is provided in the upper mold and the lower mold in correspondence with the external lead part of a semiconductor element (lead frame, etc.) Since the clamping force applied by the upper and lower dies is concentrated on the dam part, it becomes less likely that the external lead part will be damaged. Therefore, good soldering to the external lead portion is possible.

[Field of Application] The present invention can be applied not only to semiconductor devices but also to resin molding of general electronic components.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams of a conventional semiconductor molding device, FIGS. 3 and 4 are explanatory diagrams of a semiconductor molding device of the present invention, and FIG. 5 is a case in which a thick mold pad is formed on the external lead portion. 6(a) and 6(b) are explanatory diagrams showing the state before and after removal of mold burrs. 1... Upper die, 2... Lower die, 3... Lead frame, 4... Cavity, 5... Date, 6... Runner, 7... Dam, butt... External lead Part, 9... Thin Paris, 11... Upper die, 12... Lower die, 13... Lead frame, 14... Cavity, 15... Date, 16... Liner, 17...・Internal lead part, 18
...External lead part, 20...Tab, 21...Cavity, 25...Date, 27...Mold burr,
28...Dam outer surface, 29...Mold main part, 3
0...Paris in Kurete, 31...Folding type (lower type), 4th
Figure 5 Figure 6 - C'J

Claims (1)

[Claims] A resin molding method for electronic components, in which a cavity is provided between an upper mold and a lower mold corresponding to the main part of a lead frame, and resin is injected into the cavity to mold the electronic component, the dam part of the lead frame being molded. The lead frame is held down by an upper mold and a lower mold, and another cavity is provided at a location corresponding to the external lead part of the lead frame, and resin is injected into the cavity provided to correspond to the main part. Characteristic resin molding method for electronic components.