JPS6022819B2 - Mold for semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for molding a semiconductor element, and more particularly to a semiconductor element in a semiconductor device in which a mold is formed by molding a semiconductor element and a part of an IJ card with a synthetic resin. This invention relates to an improved structure of a molding die.

An example of a synthetic resin (hereinafter abbreviated as resin) using a lead frame is shown in a perspective view in FIG.

In the figure, 1 is a resin mold part that forms part of the outer container, and 2a, 2b, and 2c are all semiconductor elements (
A lead for leading out the electrode of the semiconductor element (not shown), whose tip is formed on the element mounting base, and the electrode of the semiconductor element (abbreviated as non-wire element) arranged on this lead. is connected to each lead by a bonding wire, and a part of the element lead is molded by the resin mold part. A semiconductor device having such a structure as shown in FIG.
A semiconductor element (illustrated in perspective) 3 is disposed on a lead frame 2 in which multiple sets of leads are supported by bridge parts 2e and 2f, and the electrodes are connected to corresponding leads 2a and 2c by bonding wires 4a and 4c. The assembly connected to the transfer molding machine is inserted into a molding die of a transfer molding machine to achieve molding as shown in FIG. Next, the leads, including the bridging portions 2e and 2f of the leads, are formed by press cutting, resulting in the shape shown in FIG. In the coating formation using the transfer mold described above, the portion where the lead 2a is closer to the mold than the bridge portion 2e is shown in FIG. 4 and FIG. 7 which shows the upper mold of the mold, and further shows the lower mold of the mold. The lead guide shown in FIG. 8 allows a structure in which the resin is firmly held in the vertical direction (direction facing the main surface of the lead) so that the resin does not leak even when resin pressure is applied during resin sealing.

However, the dimensional accuracy of the press processing or etching of the pitch of the side surfaces (left and right direction) of the leads, the dimensional accuracy of the transfer mold mold and the lower lead guide, and the resin sealing work is performed at high temperatures of around 150°C. Due to the problem of mutual deformation due to heat between the lead frame and the transfer mold mold, etc., as shown in Fig. A gap 6a between the lead 2a and the lead guide side surface of the lower die 5b in the mold die 5,
A structure in which 6a' is provided on the 0.1 to 0.3 side is generally used. For this reason, the resin flows into the gap as shown in cross section in FIG. 5 at the part y between the mold resin part 1 and the bridge part 2e of the lead frame shown in FIG. 3 of the product after resin sealing. 20a, 20a', 20b, 2 from Komi resin'
0b', 20c, 20c' are generated. This resin burr must be removed because it becomes a major hindrance when soldering to the leads in the next step, but it is almost impossible to remove it completely without damaging the surface of the leads. In response to the above, it is common practice to make the gap between the lead guides very small, but in this case, due to problems such as the dimensional accuracy of the pitch of the lead frame, the dimensional accuracy of the transfer mold mold, and thermal deformation, etc. When the lead frame was inserted into the mold, there was a part where the lead frame did not fit properly in the lower lead guide of the transfer mold mold, and as shown in Fig. 6, the leads 2a, 2b,
The sides of the reeds 2c are shaved to form the reed pressure portions 200a,
200, 200b, 200b', 200c, 200c
′ occurs. Fig. 7 shows the upper mold 5a of the molding die, and Fig. 8 shows the lower mold 5b. Fig. a is a side view, Fig. b is a front view, and Fig. C is a side view perpendicular to Fig. a. Figures are shown respectively.

In the figure, 7 is a lead guide, 8a, 8, and 8b, 8b' are mounting holes for cavity blocks provided in the upper mold and the lower mold. The present invention addresses the above-mentioned problems and provides an improved structure for a mold for a semiconductor element.

The molding die according to the present invention has a cavity formed on the mating surface of one of the molds so as to accommodate the lead frame, which is deeper than the plate thickness of the lead frame, and whose lower part is used to fit the cavity in the lead frame. The mold is formed in close contact with the entry side main surface and the side surface and widened toward the mating surface side, and the other mold is provided with a protrusion corresponding to a cavity formed so as to be in close contact with only the other main surface of the lead frame. , characterized in that a gap is provided between the opposing surfaces of both molds.

Next, the present invention will be described in detail with reference to the drawings regarding an embodiment of a mold for a semiconductor element.

9 and 10 show the upper die 1 of the molding die 15.
5a and the lower mold 15b, respectively, where figure a is a side view and figure b is a side view.
FIG. 2 is an enlarged view of a part of the lead guide section in FIG. first,
In FIG. 10, the cavity 17b drilled in the joint surface with the upper die is deeper than the plate thickness of the lead frame, and the lower part 17 is in close contact with the main surface and side surface of the lead frame on the side where the cavity is charged. , and the side wall reaching the mating surface side is widened to become a guide portion 17b'' formed by combining a slope 27b' and a curved surface 27b''. Next, the upper mold 15a is formed with a protrusion 17a that faces the cavity 17b of the lower mold, the top surface 17a' of which is in close contact with the upper surface of the lead frame in the cavity, and the side surface 17a'' of the projection 17a that faces the cavity 17b of the lower mold. As shown in FIG. 11, which shows the mounting state along the portion 17b'', gaps 9a, 9b, . . . , 9i are formed with sufficient conductance. In addition, 18a
, 18a', 18b, and 18b' are all attachment holes to a cavity block (not shown). As described above, the molding die according to the present invention has the following advantages.

'1} Since it is extremely easy to insert the IJ lead frame into the cavity, deformation defects of the lead frame will not occur.

Furthermore, even if the mold is deformed due to long-term use, it is easy to insert the lead frame. '21 Since the lead frame is correctly inserted into the cavity, when the upper and lower molds are joined, the mold resin is completely sealed, preventing unwanted adhesion of the mold resin to the peripheral surface of the lead. "Resin burrs" were prevented. This eliminates the need for the difficult work of removing "resin burrs," improving process efficiency and significantly reducing lead damage and lead soldering defects. '3
'Since the air gap inside the mold has sufficient conductance, it is possible to prevent resin filling defects, pinholes in the resin, resin burrs, etc. The present invention is not limited to the above transistors, but can be widely applied to resin molds, transfer molds, etc. of semiconductor devices including thyristors, ICs, and other resin molded envelopes.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the semiconductor device, FIG. 2 is a front view showing the lead frame assembly after resin molding and partially transparent, and FIG. 3 is a perspective view showing a portion of FIG. 2. , FIG. 4 is a cross-sectional view showing the state of the lead frame in the mold with respect to the AN twill part in FIG. 3, FIGS. 5 and 6 are both cross-sectional views of a part of the semiconductor device, and FIG. FIG. 8 shows the upper mold, FIG. 8 shows the lower mold, FIGS. a and c show a side view, FIG. , FIG. 9 is an upper mold, FIG. 10 is a lower mold, FIG. a is a side view, FIG. b is an enlarged cross-sectional view of a part of FIG. FIG. 3 is a cross-sectional view for explaining a mold using a metal mold. Note that the same reference numerals in the figures indicate the same or corresponding parts, respectively. 1, 1'...Resin mold part, 2...Lead frame, 15...Molding die, 15a...
- Upper die of the molding die, 15b... Lower die of the molding die, 17a... Projection of the upper die, 17
b... lower mold cavity, 17b'... lower part of the cavity, 17b''... guide part of the cavity, 9a,
9b...9i...Void on joint surface. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11

Claims (1)

[Claims] 1. In a mold in which upper and lower molds are joined at their respective mating surfaces, the cavity formed on the mating surface of one of the molds into which the lead frame is inserted is deeper than the plate thickness of the lead frame and The lower part is in close contact with the main surface and side surface of the lead frame on the charging side to the cavity, and is widened on both sides to form a guide part, and the other mold is connected only to the other main surface of the lead frame. A mold for molding a semiconductor device, comprising a protrusion corresponding to a cavity that is formed in close contact with each other, and a gap is provided between opposing surfaces of the two molds.