JPS62144335A - Sealing method for semiconductor device - Google Patents

Abstract

PURPOSE:To thin the total thickness of a semiconductor device, to prevent the generation of voids in a potting resin and to enable sealing having high reliability by irradiating the semiconductor device, on which an ultraviolet-curing type resin is potted, by ultraviolet rays and curing the resin. CONSTITUTION:An ultraviolet-curing type resin 5 is potted onto a semiconductor device 3 on a continuous film, and film substrate 11 for the potted semiconductor device 3 are moved onto a lower-surface plate 12 and stopped. An upper-surface plate 13 is lowered up to an arbitrary position, and the ultraviolet-curing type resin 5 is irradiated by ultraviolet rays through the lower-surface and upper- surface plates 13, 12 by an ultraviolet irradiator 16, and molded in desired thickness. The upper-surface plate 13 is elevated after molding, potting is completed to the film substrate 11, the semiconductor device is moved only by the next semiconductor device after molding and curing, and the process of ultraviolet-ray irradiation is started. The process are repeated. Accordingly, the resin is pushed, the potting resin is not protruded conically and can be thinned, and a molding frame, etc. are disused, thus preventing the generation of voids, thereby improving reliability.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to ICs for Katsunyu cards and ICs for identification cards.
The present invention relates to a method for sealing a thin semiconductor device used as a semiconductor device.

[Conventional technology]

Conventionally, as a method for sealing this type of semiconductor device, there has been a method called potting as shown in the cross-sectional views of FIGS. 2 and 3. (Japanese Patent Publication No. 57-177581) In Fig. 2, (1) is the first substrate, (2) is the second substrate, (3) is the semiconductor device, and (4) is the back side 1ffl, f5.
) is the potting resin, and (9) is the molding frame. In this potting method, the semiconductor device (3) is placed on the second substrate (2).
After that, the semiconductor device (3) and the pattern (6) on the first substrate (1) are connected by a connecting wire (8) by a method such as wire bonding. A molding frame (9) was attached on top of it, and potting resin was placed in the frame and cured by heating.

In Fig. 3, αυ is a film substrate, (611 is a lead frame, 611 is a bump, and α is a jig. In other potting methods, as shown in Fig. 3, a lead frame is placed on a film substrate. (g) υ is formed,
The semiconductor device (3) on which the bump f621 is formed is bonded to the lead frame H by Guyang bonding. A molding frame (9) is attached to the film substrate 0υ on which the semiconductor device (3) is mounted in this way, and this is set on the jig a0 with the film substrate Ql) facing as shown in FIG. , potting it fat (5) -
It was potted from the e-forming frame (9) side and heated and cured using a heating device. After cooling the potting resin (5), the jig (a) is removed to complete the potting work and seal the semiconductor device.

However, in the potting method shown in FIG. 2, after connecting the semiconductor device (3) and the pattern (6) of the first substrate (1) on the second substrate (2), the connecting wire (8) is covered. Because of this potting process, the total thickness of the entire semiconductor device after assembly tends to increase, making it difficult to reduce the thickness of the semiconductor device.

Furthermore, since the method shown in FIG. 3 uses a jig, the number of steps increases, resulting in poor productivity. Furthermore, in this method, the potting resin (5) needs to enter the back side of the semiconductor device (3), but when potting the resin, the jig rm
Since there is no place for nitrogen to escape, there are cases where bubbles get trapped between the back side of the semiconductor device (3) or both ends of the jig (2) and the lead frame (all). After that, an air void remained.

However, since this type of semiconductor device is thin, the distance from the package surface to the chip is short, making it easy for water to enter. Furthermore, due to the miniaturization, the mounting method on the printed circuit board is different from the conventional method, and as a result, it is susceptible to the effects of soldering heat, and there is a concern that the adhesion between the resin and the lead interface may deteriorate.

Therefore, from the above point, there is a problem in that the occurrence of voids hinders the improvement of reliability.

[Problem that the invention seeks to solve]

Conventional potting methods for encapsulating semiconductor devices have the problem that, on the one hand, the total thickness of the entire semiconductor device increases, and on the other hand, voids tend to occur in the potting resin after potting, resulting in a lack of reliability. There was a point.

This invention was made in order to solve the drawbacks of the conventional devices.It reduces the total thickness of the semiconductor device, prevents voids from forming in the potting resin after potting, and makes the semiconductor device highly reliable. The purpose is to provide a device for the Murakami method.

[Means for solving problems]

In the method for encapsulating a semiconductor device of the present invention, a semiconductor device mounted on a film substrate and potted with an ultraviolet curable resin is held with a desired gap between upper and lower plates, and the ultraviolet curable resin is pressed. It is cured by irradiating it with ultraviolet light.

[Effect]

In this invention, by adjusting the gap between the upper and lower plates, it is possible to arbitrarily control the sealing of the semiconductor device with the potting resin. Also, since it is pressed, the potting resin can be made thinner without swelling up. Furthermore, since molding frames and the like are eliminated, the occurrence of voids can be prevented and reliability can be improved.

[Example] In the following, an example of the present invention will be explained with reference to FIG.
This is a film substrate for mounting a semiconductor on which a lead frame f611 is formed on the top surface. The semiconductor device (3) is bonded to the lead frame (611) by gigantic bonding. (5) is an ultraviolet curable potting resin, and the bottom is a bottom plate (13 is a top plate, both of which are transparent and allow ultraviolet rays to pass through well. The top plate σ3 is made of glass such as quartz glass, Pyrex, float plate glass, or plano glass such as polycarbonate or acrylic.The top plate σ3 is made of a bottom plate (
6) Lower the upper and lower plates (2
) (2) It is constructed so that it can be stopped with a desired gap formed between the two. αG is an ultraviolet irradiation device,
It is configured so that ultraviolet rays can be irradiated through the upper and lower plates. Here, the film substrate αη is 35 m
It has the same shape as ttt photographic film, has sprocket holes, and can be moved at regular intervals by the sprocket.Therefore, the semiconductor device (3) on the continuous film is produced by a dispensing machine (not shown).
The fillem substrate α on which the ultraviolet curing resin (5) is potted and the potted semiconductor device (3) is mounted in the above-described manner moves onto the lower plate (2) and stops, and then the upper plate μs is lowered to an arbitrary position, and the ultraviolet curable resin (5) is irradiated with ultraviolet rays through the upper and lower plates a3U by the ultraviolet irradiation device ae to be cured and molded to a desired thickness. After molding, the upper plate (2) is raised, and then the film substrate αυ completes its potting, moves to the molding and curing stage by the amount of the next semiconductor, and begins the ultraviolet irradiation process. Thereafter, this process is repeated to form an automatic potting system.

In Example 1, Subirac T510-7 (ultraviolet curing resin), a trade name manufactured by Showa Kobunshi Co., Ltd., was used as the potting resin, and curing was completed in ultraviolet irradiation time (500 W) for 200 seconds. In addition, in Example 2, ultraviolet curing,
Heat curing resin, V manufactured by Toyobo Co., Ltd. (T-4), after 5 seconds of UV irradiation, heat in a heating oven at 150°C30
Curing was carried out by batch processing for minutes. As a result, good results were obtained in both cases. However, unlike Example 1, Example 2 required after-curing in a heating furnace after UV irradiation due to the combination of heating, but the potting work was automated. Considering the situation, it seems that a combination type with short takt time on an automated line is more suitable.

(Heating is done in batch processing because the semiconductor is placed on a continuous film carrier).

Further, in the example, quartz plate glass was used for the upper and lower plates, and a silicone-based mold release agent was applied thereto.

As described above, according to the present invention, by adjusting the gap between the upper and lower plates, it is possible to arbitrarily control the sealing of the semiconductor device with the potting resin. Note that it is more effective to vary the amount of ultraviolet curing resin potted into the semiconductor device. At this time, since there is no jig as shown in FIG. 3, there is no air resistance where the potting resin spreads, and therefore there is no fear of bubbles entering. In addition, with the conventional method, the surface shape of the potted fat after potting would be raised in a hilly shape due to surface tension, but according to the present invention, it is pressed by the top plate, so it is not possible to obtain a flat surface. , it became possible to pottute thinner to compensate for the fact that it had climbed up to the top of the mountain.Furthermore, there was no longer a need for a molding frame.

The viscosity of the resin used in the examples was 1000 cps.
-2000 cps, but the same effect can be obtained with a low viscosity resin of 1000 cps or less. (If the viscosity is low, it will flow easily, but since the resin is between the two plates, it will maintain its shape due to surface tension.)
In addition, in the high viscosity range, similar effects have been obtained in preliminary experiments with clear resins up to 100,000 cps.

In addition, for filler-containing resin, VHT-, i, a UV-heated resin made by Toyobo Co., Ltd., was mixed with Listalai)-AA made by Ryumori KK in a ratio of 1:2 (weight), and approximately 40%
Good results were also obtained when used at 10,000 cps.

(Even though it is 400,000 cps, the viscosity of the clear resin is low, so it is fluid as a draw, but the clear resin
If it exceeds 00,000 cps, there will be no liquidity. This results in the inclusion of bubbles, making it unsuitable for use. ) Furthermore, it goes without saying that the same effect can be achieved no matter which heating method is used in combination with heating, such as an electric oven, infrared heating, far infrared heating, etc.

〔Effect of the invention〕

As described above, according to the present invention, a semiconductor device mounted on a semiconductor mounting film substrate and having an ultraviolet curable resin potted thereon is held with a gap between the upper and lower plates, and the ultraviolet curable resin is placed on the semiconductor device. By irradiating ultraviolet rays while being pressed and curing, the total thickness of the semi-four-piece device can be reduced, preventing voids from forming in the potting resin after potting, and sealing semiconductor devices with high reliability. There is an effect that can be done.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a method of sealing a semiconductor device according to an embodiment of the present invention, and FIGS. 2 and 8 are cross-sectional views showing conventional methods of sealing a semiconductor device. In the figure, (3) is a semiconductor device, (5) is an ultraviolet curable resin, Qυ is a film substrate for mounting on a semi-quadruple tower, @ is a bottom plate, α3 is a top plate, Q4) is a gap, and aQ is an ultraviolet irradiation device. N f8D is a lead frame. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] (1) A step of potting an ultraviolet curable resin onto a semiconductor device mounted on a semiconductor mounting film substrate, a step of placing the semiconductor device on a lower plate, and a step of potting the ultraviolet curable resin on the lower plate. Holding the semiconductor device with a desired gap between the upper and lower plates, pressing the ultraviolet curable resin, and irradiating the ultraviolet curable resin with ultraviolet light that has passed through at least one of the plates; A method for sealing a semiconductor device, comprising curing the ultraviolet curable resin. (2) The method for sealing a semiconductor device according to claim 1, wherein the upper and lower plates are both transparent to ultraviolet rays, and the ultraviolet rays are irradiated through the upper and lower plates. (3) Claim 1 or 2 in which the upper plate is moved up and down to adjust the gap between both plates.
A method for sealing a semiconductor device as described in . (4) The method for sealing a semiconductor device according to any one of claims 1 to 3, wherein the ultraviolet curable resin is a resin combined with ultraviolet heating.