JP2002280604A - Optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical semiconductor device having excellent solder heat resistance, solder re-flow resistance and high reliability without changing the constituting member of a conventional optical semiconductor device by thermally aging in the final step of assembling. SOLUTION: The optical semiconductor device is obtained by mounting an optical semiconductor element of a IIIB-VB compound semiconductor with a resin composition, molding the element with a transparent sealing resin, and then passing the element through a step of aging the element at 80 to 200 deg.C for 8 to 48 hours.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device in which an optical semiconductor element is mounted on a resin, and has an advantage that it has excellent solder heat resistance and has little voltage fluctuation before and after solder reflow.

[0002]

2. Description of the Related Art An optical semiconductor device using a light emitting diode (LED) or the like which has been put to practical use for various displays, etc.
It is manufactured by bonding an optical semiconductor element to a predetermined portion of a thin metal plate (lead frame), a metal dish, or a resin substrate with a conductive paste or the like, and then sealing it with a transparent sealing resin or the like. The step of connecting the optical semiconductor element is one of the important steps that affect the long-term reliability of the device, particularly the VF characteristic and the luminance deterioration of the LED.

[0003]

With the recent trend toward lead-free soldering, there has been a movement to raise the temperature of the solder joint from the conventional 200 to 240 ° C. to 260 to 280 ° C. Along with this,
Optical semiconductor devices have also been required to have higher solder reflow resistance than ever before. In particular, at the interface between the electrode of the optical semiconductor element and the conductive paste, internal stress generated during curing of the conductive paste remains, so that an external stress due to solder reflow at a high temperature or the like causes interface cracks or element peeling. Is generated, which causes VF characteristic failure and electrical open of the optical semiconductor device.

[0004] As a countermeasure against this, a method of increasing the heat resistance of the conductive paste for mounting the optical semiconductor element, particularly the adhesion during heat, has been conventionally taken. In many cases, and as a result, the water absorption rate was increased, and the moisture resistance reliability tended to be poor. In addition, resins having high heat resistance generally tend to have high elasticity and rather increase internal stress, and therefore, there is a high possibility that chip peeling due to heat history during the assembly process and the mounting process becomes a problem.

Therefore, there has been a strong demand for the development of a highly reliable optical semiconductor device having excellent solder reflow resistance in order to improve physical and electrical bonding reliability.

The present invention has been made in view of the above circumstances, and provides a highly reliable optical semiconductor device having excellent solder heat resistance and solder reflow resistance without changing the components of a conventional optical semiconductor device. It is something to offer.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has achieved the above object by introducing a heat aging step in the final step of assembling an optical semiconductor device. The inventors have found what can be achieved and completed the present invention.

That is, according to the present invention, an aging step is carried out at a temperature of 80 ° C. to 200 ° C. for 8 to 48 hours after mounting a 3B-5B group compound semiconductor device with a resin composition and molding with a transparent sealing resin. An optical semiconductor device characterized by passing through.

Hereinafter, the present invention will be described in detail.

As an optical semiconductor device used in the present invention, G
aAlAs, GaP, GaInAsP, InP, GaN
And other compound semiconductor devices such as SiC.

As the resin composition used for the mount of the present invention, an epoxy resin is generally used. Depending on the structure of the optical semiconductor element, either a conductive resin composition or an insulating resin composition is used. . In the case of an organic binder having a low heat resistance, a temperature of 121 ° C., 2
Under conditions such as a pressure cooker test at atmospheric pressure, the cured film of the resin composition deteriorates. Therefore, when reliability under such severe conditions is required, it is necessary to select a binder having high heat resistance. For example, a system in which a polyimide-modified resin or a novolak epoxy resin having an average number of epoxy groups of 3 or more is cured with a phenol resin is used.

As a sealing resin used for resin sealing of the mounted optical semiconductor element, a transparent resin generally used for optical semiconductors is used. Generally, a bifunctional epoxy resin / acid anhydride is used. A curing type sealing resin is used.

The heat aging step performed after the curing of the transparent sealing resin is a necessary step for realizing the optical semiconductor device of the present invention.

Although there is no particular limitation on the heat source, a heat source that does not apply rapid heat to the optical semiconductor device, such as a hot air circulation oven or a tunnel furnace, is more preferable. If a heat plate is used as a heat source, the optical semiconductor device may be placed directly in a metal case or the like having good heat conductivity instead of being directly placed on the heat plate to conduct heat indirectly.

The temperature for heat aging is from 80 ° C. to 200 ° C.
Can be arbitrarily selected in the range of
C. to 150.degree. C. is good. If the temperature of thermal aging is lower than 80 ° C, the aging effect cannot be expected. On the other hand, if the temperature exceeds 200 ° C, oxidation or discoloration of the metal frame and thermal deterioration of the mounting resin composition or the transparent sealing resin may cause the base material to deteriorate. There is a concern that the adhesion may decrease or cracks may occur.

The heat aging time can be arbitrarily selected within the range of 8 to 48 hours, but is preferably 12 to 24 hours. If the heat aging time is less than 8 hours, the aging effect cannot be expected, and if it exceeds 48 hours,
Oxidation and discoloration of the metal frame, and thermal degradation of the mount resin composition and the transparent sealing resin may cause a decrease in adhesion to the substrate or cracks.

Furthermore, when oxidation of the metal frame is feared due to high temperature aging, it is necessary to replace the atmosphere in the heat source with an inert gas such as nitrogen.

The optical semiconductor device of the present invention is manufactured as follows. After mounting the electrode surface of an optical semiconductor device such as GaAlAs on a lead frame with a conductive paste or the like, curing under predetermined curing conditions, performing wire bonding, sealing and curing with a transparent sealing resin, and finally, oven and the like. Aging is performed, and the lead frame is cut off to manufacture an optical semiconductor device.

[0019]

According to the present invention, in the final assembly process of an optical semiconductor device,
By performing thermal aging under appropriate conditions, it acts as an after-curing to the resin composition and the transparent encapsulant mounting the optical semiconductor element, thereby improving the adhesion of these resins to the base material. effective. Further, the stress generated inside the device, particularly at the element interface due to the curing of these resins, is reduced by passing through this heat aging process,
Even when a stress is further applied to the element interface due to heat shock or the like, sufficient contact with the base material can be maintained, and the electrical reliability of the optical semiconductor device is improved.

According to this method, an optical semiconductor having superior solder heat resistance and solder reflow properties can be obtained without changing the components such as a resin mount material and a transparent sealing material used in the conventional optical semiconductor device. A device can be obtained.

[0021]

Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Examples 1-2 Using a commercially available epoxy resin / phenol-cured solventless silver conductive paste (A), a dish-shaped lead frame and a 0.3 mm × 0.3 mm GaAlAs-based lead frame were used. The optical semiconductor element (LED chip) is mounted and cured under predetermined curing conditions for each conductive paste, wire-bonded, and then sealed with a commercially available general epoxy resin / acid anhydride transparent sealing material. Curing (120 ℃ × 2H + 13
(0 ° C. × 6 H) to assemble the optical semiconductor device.

The assembled optical semiconductor device was subjected to a thermal aging process in a hot air circulation type oven within the range of the thermal aging conditions of the present invention, and optical semiconductor devices of Examples 1 and 2 were prepared.

Examples 3 and 4 Using a commercially available epoxy resin / dicyandiamide-curable solvent-type silver-based conductive paste (B), a dish-shaped lead frame and 0.3 mm × 0.3 mm GaAlAs were used.
The optical semiconductor element (LED chip) is mounted and cured under predetermined curing conditions for each conductive paste, wire bonding is performed, and then a commercially available general epoxy resin /
Sealing and curing with acid anhydride transparent sealing material (120 ℃ × 2H +
(130 ° C. × 6H) to assemble the optical semiconductor devices.

The assembled optical semiconductor device was subjected to a thermal aging process in a hot air circulation type oven within the range of the thermal aging conditions of the present invention, whereby optical semiconductor devices of Examples 3 and 4 were prepared.

Comparative Examples 1 to 3 Using a commercially available epoxy resin / phenol-cured solventless silver-based conductive paste (A), a dish-shaped lead frame and a 0.3 mm × 0.3 mm GaAlAs-based lead frame were used. The optical semiconductor element (LED chip) is mounted and cured under predetermined curing conditions for each conductive paste, wire-bonded, and then sealed with a commercially available general epoxy resin / acid anhydride transparent sealing material. Curing (120 ℃ × 2H + 13
(0 ° C. × 6 H) to assemble the optical semiconductor devices.

The assembled optical semiconductor device was subjected to a heat aging process in a hot air circulating oven under conditions other than the heat aging conditions of the present invention and those not subjected to heat aging, to prepare optical semiconductor devices of Comparative Examples 1 to 3.

Comparative Examples 4 to 6 Using a commercially available epoxy resin / dicyandiamide-curable solvent-type silver-based conductive paste (B), a dish-shaped lead frame and 0.3 mm × 0.3 mm GaAlAs were used.
The optical semiconductor element (LED chip) is mounted and cured under predetermined curing conditions for each conductive paste, wire bonding is performed, and then a commercially available general epoxy resin /
Sealing and curing with acid anhydride transparent sealing material (120 ℃ × 2H +
(130 ° C. × 6H) to assemble the optical semiconductor devices.

The assembled optical semiconductor devices were subjected to a heat aging step in a hot air circulating oven under conditions other than those not subject to heat aging and under the conditions other than the heat aging conditions of the present invention to prepare optical semiconductor devices of Comparative Examples 4 to 6.

The optical semiconductor devices obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were subjected to a solder heat resistance test at 260 ° C. and 280 ° C. after moisture absorption at 85 ° C./85% RH for 72 hours. The value variation (ΔVF) was compared. The results are shown in Tables 1 and 2. As a result, the present invention was excellent in both cases, and remarkable effects of the present invention were recognized.

[0031]

[Table 1] * 1: After leaving for 72H under the condition of 85 ° C / 85% RH,
Mold resin part 5 seconds, lead part 10 seconds, solder immersion,
The voltage (VF) at the time of normal-temperature energization (forward current 30 mA) was measured. The number of optical semiconductor devices subjected to the test is 20 each.

* 2: For a sample in which the maximum VF fluctuation occurred before and after moisture absorption, it indicates how many times the VF after moisture absorption increased before moisture absorption.

[0033]

[Table 2] * 1: After leaving for 72H under the condition of 85 ° C / 85% RH,
Mold resin part 5 seconds, lead part 10 seconds, solder immersion,
The voltage (VF) at the time of normal temperature current application (forward current 30 mA) was measured. The number of optical semiconductor devices subjected to the test is 20 each.

* 2: For the sample in which the maximum VF fluctuation occurred before and after moisture absorption, it indicates how many times the VF after moisture absorption increased compared to before moisture absorption.

[0035]

As is clear from the above description and Tables 1 and 2, the optical semiconductor device of the present invention can be heat-aged in the final step of assembling, so that the conventional material components can be changed. When using high-temperature solder near 260 to 280 ° C. due to the lead-free process, it is possible to improve the physical and electrical bonding reliability of the element and to suppress the VF fluctuation of the optical semiconductor device, which is very industrially useful. Things.

Claims (1)

[Claims] 1. An optical semiconductor device of a 3B-5B group compound semiconductor or the like is mounted with a resin composition, molded with a transparent sealing resin, and then passed through an aging step at a temperature of 80 ° C. to 200 ° C. for 8 to 48 hours. An optical semiconductor device, comprising: