JP2810343B2 - Resin sealing method for optical semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin sealing method for an optical semiconductor device for sealing a semiconductor chip on a lead frame with a resin.

[0002]

2. Description of the Related Art An optical semiconductor device for performing signal conversion between an optical signal and an electric signal using a light emitting diode (LED), a phototransistor, or the like generally has a light emitting property or a light receiving property mounted on a lead as an electrode. It is formed by sealing a transparent semiconductor chip with a transparent resin.

An optical semiconductor device of this type is manufactured by using an LED.
Taking the element as an example, a semiconductor chip in which a PN junction surface is formed between regions of different conductivity types by the introduction of impurities is formed integrally with an island on which the semiconductor chip is mounted, and a first lead and an First, a lead frame made of a conductive metal is formed by mutually forming a second lead as the other electrode extending parallel to one lead, and a semiconductor chip is electrically connected to each island of the lead frame by die bonding. The semiconductor device is mounted and fixed in a state, and then the upper electrode provided on the upper surface of the semiconductor chip is electrically connected to the tip of the second lead facing the upper electrode by wire bonding to perform an assembling process.

[0004] When such an assembling process on the lead frame is completed, the lead frame 22 on which the semiconductor chip 21 is mounted is sandwiched between the upper die 23 and the lower die 24 as shown in FIG. The semiconductor chip 21 is sealed with resin by injecting a transparent molten resin into a cavity defined between the upper and lower molds via a gate (not shown) and curing the resin.

[0005]

By the way, in a general semiconductor device such as an IC which does not perform a function such as transmission or conversion of light, various kinds of light-transmitting molten resin are used to adjust properties such as viscosity. Although the sealing is performed by mixing the filler, as described above, in an optical semiconductor element that performs transmission or conversion by light between the inside and the outside of the element, in order to secure a required light transmitting property, The sealing process must be performed without mixing a filler into the material.

For this reason, when a minute gap is present between the molds at the time of resin sealing, if a normal opaque resin is used, the filler mixed in the resin fills or entangles the minute gap. Although leakage of the resin to the outside of the cavity of the resin, for example, between the molds, can be suppressed to a considerable extent, in the case of an optical semiconductor element using a translucent resin, as described above, the resin is filled with a filler. Since they cannot be mixed, leakage of the molten resin through minute gaps between the molds inevitably occurs.

[0007] For this reason, the lead portion of the lead frame after the resin encapsulation step has a wide area, for example, 2
-3μm thick thin burr and relatively thick,
For example, thick burrs having a thickness of about 0.5 to 0.6 mm are formed, which causes complications in steps such as removal of resin burrs performed after resin encapsulation or lowers product yield. There is inconvenience to do. In particular, when the resin burr adheres longer along the lead portion on the tip side than the dam bar of the lead frame, the removal becomes more difficult.

Accordingly, it is an object of the present invention to suppress leakage of resin from a mold cavity at the time of resin sealing by a relatively simple method, thereby improving the efficiency of the semiconductor element manufacturing process.

[0009]

According to a first aspect of the present invention, there is provided a resin sealing method for an optical semiconductor device, comprising: a lead frame having a lead portion electrically connected to a semiconductor chip and a dam bar portion connecting the lead portion; A method for manufacturing an optical semiconductor device comprising injecting a transparent resin into a cavity defined between an upper mold and a lower mold while being sandwiched between a mold and a lower mold,
It is characterized in that a transparent resin is injected into the cavity after the end of the dam bar of the lead frame is pressed and deformed between the upper mold and the lower mold.

[0010] With this configuration, even when the upper and lower molds are molded and a transparent resin that is likely to leak is injected into the cavity defined between the upper and lower molds, the upper and lower molds are inserted between the two molds. In addition to holding the dam bar 5b in close contact, the end of the dam bar 5b is deformed in the groove of the bush block to fill the groove, so that even if the resin injected into the cavity leaks into the gap between both the molds, the dam bar and its end Leaks in the direction of the tip of the lead are effectively prevented at the portion of the bushing block.

According to a second aspect of the present invention, there is provided a resin sealing method for an optical semiconductor device according to the first aspect, wherein the protrusion of the dam bar is formed on at least one of the upper and lower mold surfaces in a direction perpendicular to the dam bar. Through the process. By deforming the dam bar by the action of such a projection, leakage of the molten resin in the direction of the lead tip can be more reliably prevented.

[0012]

Next, an embodiment of the method of the present invention will be described in detail with reference to FIGS. The resin sealing method of the present invention is carried out using a mold including an upper mold and a lower mold. FIG. 1 shows a mold on which a resin-sealed lead frame is mounted, with its upper mold removed.

As shown in FIG. 1, the lower mold 1 comprises, for example, a chaser block 2 and a cavity block 3 housed and held in the chaser block 2. One end of the cavity block 3 is similarly housed in the chaser block 1. While being in contact with the held end block 4,
The other end is in contact with a center block (not shown) for supplying the molten resin.

The cavity block 3 has a lower concave portion 6 defining a cavity in cooperation with an upper die for sealing a semiconductor chip mounted on an island of the lead frame 5 with a resin, and a resin in the cavity. Gates 8 are respectively formed in the lower recesses of the runner 7 for supplying and the resin from the runner 7. The lead frame 5 mounted on the lower mold 1 has leads 5a constituting electrodes of the optical semiconductor device.
And a dam bar 5b for connecting the leads to each other. Here, the dam bar 5b linearly extends to a position on the lead 5a adjacent to the resin sealing body on the lead 5a, and its end is placed on a bush block 9 described later. The dam bar end and the bush block on which the dam bar is mounted are similarly provided on the center block (not shown).

FIG. 2 shows an enlarged cross section taken along line AA of FIG. 1 in a state where the upper mold 10 is fitted on the lower mold 1. In the figure, the molten resin 13 is injected into the cavity between the lower concave portion 6 of the lower die 1 and the upper concave portion 11 of the upper die 10 through the gate 8. The lead frame 5 is sandwiched between the two dies 1 and 10 in a pressing manner during the mold matching.

A mold surface is formed on the lower mold 1 where the dam bar 5b is disposed so as to provide a mold gap between the lower mold 1 and the upper mold 10 that is slightly smaller than the thickness of the dam bar 5b. In addition, flank surfaces 1a and 10a are provided on the upper and lower molds 1 and 10 at the portions where the distal ends of the leads 5a are arranged so as to provide a mold gap slightly larger than the thickness of the dam bar 5b. By arranging the mold surface in this way, when the molten resin is injected into the cavity in a state where the molds are matched, the resin leaked from the cavity and the like is sandwiched between the upper and lower molds 1 and 10 with a sufficient pressure. Dam bar 5b
This prevents the leakage resin from spreading to the lead tip side, to the right in FIG.

Here, when a transparent resin such as an epoxy resin is used as the sealing resin, unlike the general opaque resin from the viewpoint of securing transparency, no filler is mixed as described above. Although leakage into gaps and the like becomes a problem, by employing the method of the present invention, the problem of leakage of resin or generation of burrs on lead portions can be greatly reduced.

FIG. 3 shows the bush block 9 in a state where the end 5c of the dam bar 5b is arranged and the vicinity thereof. As shown in a plan view in FIG. 3A, the bush block 9 is provided at a location adjacent to the end block in the cavity block 3 of the lower mold 1, and is best shown in a side view of the end block in FIG. Thus, a groove 9a for receiving the dam bar end 5c is provided. The groove 9a is provided at the end 5 of the dam bar.
It is formed with a minute amount, for example, 0.1 mm, a large width W, and a minute amount, for example, 0.2 mm, with a small depth D with respect to the cross-sectional dimension of c. By setting the groove 9a to such dimensions, when the upper die 10 is matched, the dam bar end 5c receives a pressing force in the groove 9a by the upper die 10; The inside of the groove 9a whose upper part is covered by the upper mold 10 is closed by being deformed so as to expand in the middle and left and right directions.

For this reason, when the upper and lower dies 1 and 10 are combined and the resin is injected into the cavity defined therebetween, the dam bar 5b is held between the two dies 1 and 10 in close contact with each other. The end is deformed in the groove 9a of the bush block 9 to close the groove 9a, so that even if a part of the resin injected into the cavity leaks into the gap between the two molds 1 and 10, With the dam bar 5b sandwiched in a shape and the closed groove portion 9a of the bush block 9 at the end thereof,
The expansion of the leakage of the lead 5a in the tip direction is effectively prevented.

In this case, the resin burr formed on the cavity side of the dam bar 5b has a relatively narrow range.
When the dam bar 5b is punched in a later step, the dam bar 5b can be easily punched and removed therewith. On the contrary,
Grease burrs that adhere to a wide area on the lead portion on the tip side (anti-cavity side), which is usually formed much longer than the cavity side, are difficult to remove even by punching. Although it is almost impossible to remove the resin burrs by using the method of the present invention, it is possible to effectively prevent the formation of such resin burrs on the lead tip side.

FIG. 4 shows another embodiment of the bush block used in the resin sealing method of the present invention. In the form of the bush block 9 in this embodiment, as shown in FIG. 4A, except that the protrusion 9 is provided in the groove 9a so as to extend in a direction perpendicular to the dam bar, that is, the height of the protrusion changes in the groove direction. For example, the configuration is the same as that of the above-described bush block. When sealing the lead frame with resin, the end 5c of the dam bar 5b is
As shown in (a), it is placed on the protrusion 12 provided on the bottom surface of the groove 9a of the bush block 9. In this state, by lowering the upper mold 10 toward the lower mold 1 and performing mold matching, as shown in FIG. 4B, the dam bar end 5 c is pressed onto the projection 12 and is interposed via the projection 12. Subject to pressure deformation. At the time of such pressing deformation, the dam bar 5c is easily deformed in the groove 9a in the lateral direction, that is, in the front-to-back direction of the drawing sheet. As a result, the groove 9a of the bush block 9 whose upper part is closed by the upper die 10 is deformed. Sealed tightly by the dam bar end 5c.

The groove 9a is more securely tightly sealed by the deformation of the dam bar 5c due to the action of the projection 12 provided on the bush block 9, so that the upper and lower dies 1, 10
When the resin is injected into the cavity between the two dies 1, 1
The leakage of the molten resin in the direction of the lead tip can be more effectively prevented at the end 5c together with the dam bar 5b sandwiched between the zeros. In this case, even if some resin burrs are formed on the cavity side with respect to the dam bar 5b,
Since the interval between the resin sealing body and the dam bar 5c is usually set relatively short, the dam bar 5c can be easily removed when punching the lead bar from the lead frame.

[0023]

As described above in detail, according to the resin sealing method for an optical semiconductor device of the present invention, the upper and lower molds are matched and the resin is injected into the cavity defined therebetween. When doing, while holding the dam bar tightly between both molds,
Even if the resin injected into the cavity leaks into the gap between the two dies, the end is deformed in the groove of the bush block and the end is deformed in the groove of the bush block, and the end of the resin is led by the bush block at the end. Leakage of 5a in the distal direction is effectively prevented.

[0024] For this reason, the risk of forming thick burrs or the like which are difficult to remove on the lead portion on the tip side of the dam bar can be greatly reduced, so that the yield of the product is improved and the deburring work is performed by the breath together with the removal of the dam bar. It can be facilitated by punching.

[Brief description of the drawings]

FIG. 1 is a plan view showing a lower mold used in the present invention together with other elements.

FIG. 2 is a sectional view showing an embodiment of the present invention.

3A and 3B are a plan view and a cross-sectional view illustrating a main part according to the embodiment of the present invention.

FIG. 4 is a sectional view showing a main part in another example of the method of the present invention. .

FIG. 5 is a cross-sectional view showing a conventional resin-sealed state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower die 3 Cavity block 5 Lead frame 5a Lead 5b Dam bar 5c Dam bar tip 6 Lower recess 8 Gate 9 Bush block 9a Groove 10 Upper die 12 Projection

Claims (2)

(57) [Claims] An upper mold having a lead frame having a lead portion electrically connected to the semiconductor chip and a dam bar portion connecting the lead portion sandwiched between an upper mold and a lower mold; A method of manufacturing an optical semiconductor device comprising injecting a transparent resin into a cavity defined between a lower mold and a lower mold, wherein an end of a dam bar of the lead frame is connected to an upper mold and a lower mold. A method of sealing a resin for an optical semiconductor device, comprising: injecting a transparent resin into the cavity after being pressed and deformed therebetween. 2. The resin for an optical semiconductor device according to claim 1, wherein the deformation of the dam bar is performed on at least one mold surface of the upper mold and the lower mold via a projection extending in a direction perpendicular to the dam bar. Sealing method.