JP2828822B2 - Optical coupling device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding resin for an optical coupling device (photocoupler) and a manufacturing method using the same, and more particularly, to an optical coupling device which is a two-layer molded photocoupler and requires a light-emitting element to relieve stress. The present invention relates to an apparatus and a method for manufacturing the same.

[0002]

2. Description of the Related Art A method for manufacturing a conventional two-layer molded optical coupling element (photocoupler) will be described.

First, a light emitting element 1 and a light receiving element 2 as shown in FIG. 3 are die-bonded to respective lead frames 3 and 4, and wire bonds 5 are formed. A precoat is applied with resin 6.
Thereafter, the light-emitting element 1 and the light-receiving element 2 are opposed to each other so as to be optically coupled to each other by spot welding or setting on a loading frame, and a primary molding is performed with the light-transmitting resin 7. After the removal, a secondary molding is performed with the light-shielding resin 8. FIG. 4 is a flowchart showing these production methods. In FIG. 4, GL represents a single process of the light emitting element 1, and PT represents a light receiving element 2.
Shows a single step.

[0004] Alternatively, there is a method of manufacturing a single-layer mold as shown in FIG. In this method, after docking (optical path) with silicon resin 9 instead of the primary mold, the resin is covered with light-shielding resin 8.

[0005] Of the above two methods, a two-layer mold type optical coupling device shown in FIGS. 3 and 4 has recently become mainstream.

[0006]

Generally, in a two-layer mold type optical coupling device, moisture is absorbed due to a difference in expansion coefficient between the light-transmitting resin 7 and the light-shielding resin 8 during manufacturing and use. Sometimes. Then, cracks may enter the translucent resin 7.

In a low temperature range of -20 ° C. to -30 ° C., the light-transmitting resin 7 significantly contracts, and the light-emitting element 1 particularly deteriorates particularly at corners. For this reason, a quality trouble may occur.

In order to avoid this, conventionally, a means for preventing the occurrence of cracks by mixing a filler into the translucent resin 7 to reduce the difference in expansion coefficient between the translucent resin 7 and the light-shielding resin 8 is adopted.

Further, a light emitting element due to shrinkage of the light shielding resin 8
In order to prevent the deterioration of the light-emitting element 1, the light-emitting element 1 is pre-coated with the silicon resin 6 to relieve the stress.

However, since the silicon resin 6 has water permeability, when external moisture reaches the silicon resin 6 along the interface between the lead frame 3 and the resins 7 and 8, the moisture is instantaneously transmitted to the light emitting element 1 To reach. Then,
The reliability on the light emitting element 1 side is inferior to the light receiving element 2 side without the pre-coating of the silicon resin 6 in terms of moisture resistance and the like.

[0011] In addition, in view of demands for simplification of the manufacturing operation of the optical coupling element and reduction in price by continuation of the steps, it has been desired to omit the pre-coating step of the silicon resin 6.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an optical coupling element and a method of manufacturing the same which can improve reliability, simplify the manufacturing operation and reduce the cost by continuation of the steps, and the like. I do.

[0013]

SUMMARY in accordance with the present onset bright Means for Solving the Problems] is die-bonded each individual lead frames 13 and 14 of the light emitting element 11 and the light receiving element 12, and opposed to couple them optically , Contains a filler ,
Resin 17 with a low crosslink density set, or
Filler is included and the crosslinking density is lowered
And translucent resin 17 denatured with silicon for stress relaxation
The first molding is performed by directly covering the periphery of the light emitting element 11, and the second molding is performed with the light shielding resin 18.

[0014]

[0015]

In [action] above Symbol challenges solutions, for primary molded directly by the light-emitting element 11 and the light receiving element 12 a crosslink density lower translucent resin 17. Then, especially at low temperatures, the translucent tree
Reduced shrinkage of grease 17
Even without the heat, the light emitting element 11 is hardly deteriorated.

The translucent resin 17 is made of silicon denatured material.
Low-stress translucent resin that was previously required
The step of pre-coating with a silicone resin can be omitted.

[0017]

FIG. 1 is a flowchart showing a method of manufacturing an optical coupling device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing an optical coupling device according to an embodiment of the present invention.

As shown in the figure, in the optical coupling device of this embodiment, the light emitting element 11 and the light receiving element 12 are die-bonded to individual lead frames 13 and 14, respectively, and wire-bonded with a gold wire 15 or the like. The light emitting element 11 and the light receiving element 12 are opposed to each other so as to be optically coupled by spot welding or setting on a loading frame. After that, it is secondarily molded with the light shielding resin 18.

As the light emitting element 11, a general light emitting diode made of gallium arsenide is used.

As the light receiving element 12, a general silicon-based phototransistor is used.

The light-transmitting resin 17 is a light-transmitting epoxy resin containing a filler. The light-transmitting resin 17 is made of silicon to reduce stress between the light-emitting element 11 and the gallium arsenide-based light-emitting element 11, which is particularly susceptible to deterioration. Has been given.

The cross-linking density of the translucent resin 17 is lowered by, for example, absorbing moisture when the resin is cured, and the glass transition temperature Tg is set low. Thereby, the shrinkage of the translucent resin 17 at a low temperature is reduced, and the light emitting element 11
To reduce the impact.

Next, a method of manufacturing the above-described optical coupling device will be described with reference to FIG. In FIG. 1, GL indicates a single process of the light emitting element 11, and PT indicates a single process of the light receiving element 12.

First, as shown in FIGS. 1 and 2, the light emitting element 11 and the light receiving element 12 are individually connected to lead frames 13 and 14, respectively.
After die bonding, wire bonding is performed, and lead frame 1 is attached to spot welding or loading frame.
3 and 14, the light emitting element 11 and the light receiving element 12
Are primary-molded with the translucent resin 17 so as to be optically coupled.

At this time, since the translucent resin 17 is modified with silicon, silicon can be interposed in the corners of the light emitting element 11 and the like, and the deterioration thereof can be reduced.

The glass transition temperature T of the translucent resin 17
Since g is reduced, the shrinkage of the translucent resin 17 is reduced particularly in a low temperature range of −20 ° C. to −30 ° C., and the light emitting element 11 is hardly deteriorated.

Thereafter, after secondary molding with the light-shielding resin 18, an external plating such as tin plating or solder plating is applied to form. In addition, it is shipped through a test, a visual inspection, and a packing process.

Then, an optical coupling device having the same optical characteristics as that of the conventional two-layer mold type shown in FIGS. 3 and 4 can be obtained except that there is no pre-coating step using a silicone resin.

Here, external moisture may enter from the interface between the mold resins 17 and 18 and the lead frames 13 and 14. However, in the optical coupling device according to the present embodiment, the arrival time of moisture is lengthened by the amount of no silicon. Therefore, the water resistance is improved as compared with the conventional two-layer mold type, and high reliability can be realized.

Further, since the precoating step can be omitted, the continuation of the step is facilitated, so that not only the cost can be reduced by omitting the step, but also in-line can be easily coped with.

Note that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

For example, although a photocoupler has been described as an optical coupling element, it goes without saying that the present invention can also be applied to a photointerrupter or a semiconductor element sealed with resin.

In the above embodiment, the translucent resin 17 is
Although the silicon denaturation was used and the crosslinking density was low, it goes without saying that each of these means may be performed alone. For example, when the cross-link density is lowered by absorbing moisture in the light-transmitting resin, the electrical insulation decreases. However, when a non-hygroscopic resin is used for the purpose of securing the insulation, the above-described silicon denaturation ratio The effect of the stress on the light emitting element 11 may be reduced only by increasing the height.

[0034]

As is apparent from the above description, according to the first to fourth aspects of the present invention, even if the conventionally used silicon resin is omitted, the deterioration of the light emitting element can be sufficiently prevented, and the precoating step can be omitted. Thus, not only can the manufacturing cost be reduced, but also in-line can be easily accommodated.

Further, since the water-permeable silicone resin is not provided, the time required for moisture entering from the outside to reach the element is prolonged, and there is an excellent effect that the water resistance can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a manufacturing method of an optical coupling device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an optical coupling device according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional two-layer mold type optical coupling element.

FIG. 4 is a flowchart showing a method for manufacturing a conventional two-layer mold type optical coupling element.

FIG. 5 is a sectional view showing a conventional one-layer mold type optical coupling element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Light emitting element 12 Light receiving element 13, 14 Lead frame 17 Translucent resin 18 Light shielding resin

Continuation of the front page (56) References JP-A-55-157278 (JP, A) JP-A-63-14456 (JP, A) JP-A-63-14457 (JP, A) JP-A-1-126361 (JP) JP-A-3-71934 (JP, A) JP-A-2-173,034 (JP, A) JP-A-2-191622 (JP, A) JP-A-63-95221 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 31/12

Claims (4)

(57) [Claims] 1. A light emitting element and the light receiving element is die-bonded to each individual lead frame, they are primary molded at oppositely disposed with light-transmitting resin so as to optically couple the secondary at further light shielding resin in molded optical coupling device, the translucent resin, filler for reducing the difference in thermal expansion coefficient between the light-shielding resin is contained, tree
An optical coupling device, wherein a crosslink density of a fat is set to be low and the resin is directly coated around the light emitting element. 2. The light-transmitting resin is modified with silicon for stress relaxation.
Optical coupling device according to claim 1, characterized in that made the. 3. A die-bonded to each individual lead frame light-emitting element and a light receiving element, it was opposed to optically coupled to the primary molding by translucent resin, the secondary mold at the light shielding resin In the method for manufacturing an optical coupling device , a filler is contained as the translucent resin .
One cross-linking density of the resin used as the set lower the optical coupling device, characterized in that the coating directly around the light emitting element
Manufacturing method . 4. A light-transmitting resin which is further used for stress relaxation.
Claims characterized by using a denatured silicon
4. The method for manufacturing the optical coupling device according to 3 .