JP2710510B2 - Semiconductor device sealing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing a semiconductor device, and more particularly to a method for sealing a semiconductor device using a thermosetting epoxy resin as an adhesive.

[0002]

2. Description of the Related Art Conventionally, this kind of sealing method is shown in FIG.
As shown in the temperature characteristic diagrams of the thermosetting epoxy resin in FIGS. 1A and 1B, a method of sealing a semiconductor device utilizing the characteristics of the plastic region and the thermosetting region of the resin.

FIGS. 10A to 10D are cross-sectional views illustrating a typical example of a conventional method of sealing a semiconductor device in the order of the manufacturing steps of the semiconductor device. FIGS. 11A to 11C are timing charts.

As shown in FIG. 10A, a package 3 having a pellet 4 mounted thereon and connected by a bonding wire 5 is provided.
Is placed on a heating table 6 and the bonding portion of the package 3 is set at 125 ° C.
Heat for about 10 seconds. Next, the cap 1 on which the thermosetting epoxy resin 2 has been applied is sucked by the cap suction nozzle 7, and the cap 1 is lowered and mounted on the bonding portion of the package 3. This is shown in FIG. 10B, in which the thermosetting epoxy resin 2 is adapted to the bonded portion by being heated. FIG. 10C shows a state in which heating by the heating table 6 is completed and the cap 1 is temporarily bonded. The heating of the thermosetting epoxy resin 2 is performed in the state of the plastic region A that does not reach the gel point B as shown in the timing chart of FIG. In this state, as shown in FIG. 4B, the time to reach a gel point at about 125 ° C. (hereinafter, referred to as gel time) is 8 times.
Since it is as long as about 00 ° C., productivity cannot be increased.

Therefore, conventionally, a cap 1 bonded with a thermosetting epoxy resin 2 in a state shown in FIG.
Guide jig 1 having load spring 12 and package 3
0 and the guide jig 11, and fix them so that an appropriate load (approximately 100 g) is applied to the bonding portion.
Degree). As shown in the timing chart of FIG.
During the load cure in the thermostatic oven, the state of the thermosetting epoxy resin passes the gel point B, and the resin is hardened while applying a load for about 1 to 2 hours to a point C at which the resin adhesive strength in the thermosetting region is sufficient, and finally bonded. .

[0006]

In this conventional sealing method, since the thermosetting resin is temporarily bonded in a region where the thermosetting resin still shows plasticity, the thermosetting epoxy is cured during curing in a thermostatic oven. Since the resin shows plasticity and the package and cap are displaced, the cap rises and the hole that penetrates the resin becomes clear and the airtightness deteriorates, so a proper load is constantly applied to the package and cap using a guide jig. However, there was a problem that it was necessary to cure.

[0007] In addition, if an attempt is made to perform a no-load cure in the main bonding step, the resin must be heated while applying a load in the temporary bonding step until the resin reaches the gel point or above the gel point. ) Is the glass transition temperature of the resin (1
(50 ° C.), there was a problem that the bonding time was long and the productivity was poor.

[0008]

According to the method of sealing a semiconductor device of the present invention, when a package and a cap are bonded by using a thermosetting epoxy resin, a heating temperature of the resin is changed by a glass transition of the thermosetting epoxy resin. Raise the temperature, shorten the time to reach the gel point, and apply a load to reach the gel point, and then temporarily bond. In the subsequent resin curing step, even if the resin is heated again, the resin does not show plasticity, and the non-weighted curing in the subsequent step is enabled.

In the temporary bonding step, when the gelation time is shortened during heating of the resin due to a shortage of the equipment due to equipment abnormality or the like, when the equipment is stopped from immediately before heating the resin until the resin applies a load to the plastic region. Prohibit stop interrupt. Even if there is an equipment stop interrupt, while heating the resin, a load is applied to the plastic region of the resin and then the equipment is stopped. Even if there is an equipment stop interrupt, before heating the resin and applying a load, the heating of the resin is stopped and then the equipment is stopped. In this way, a means is provided to avoid applying a load after the resin has passed the gel point, either alone or in combination.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG.
(A)-(d) is sectional drawing of the order of a process of Example 1 of this invention. FIGS. 2A to 2C are timing charts showing the heating temperature of the resin, the state of the resin, and the load on the resin. As shown in FIG. 1A, a package 3 on which a pellet 4 is mounted and connected by a bonding wire 5
Is placed on a heating table 6 to heat the bonded portion of the package 3. The temperature of the heating table 6 is such that the heating temperature of the resin portion, that is, the resin, is the glass transition temperature of the thermosetting epoxy resin 2 (150 ° C.
A temperature higher than (before and after) a temperature at which the gel time becomes about 10 seconds is determined from the characteristic diagram of the resin in FIG. 4B (300 ° C. in this example).

Next, the cap 1 on which the thermosetting epoxy resin 2 is applied is sucked by the cap suction noise 7, and the cap 1 is lowered and placed on the bonding portion of the package 3. Figure 1
(B). The resin exhibits plasticity when heated, and fits into the bonding portion between the package 3 and the cap 1. Next, as shown in FIG. 1 (c), before reaching the gel point B shown in FIG. The epoxy resin fits well into the bonding area and is shaped so that highly reliable airtightness can be obtained. At this time, the cap 1 is placed on the package 3 and the pressure is not immediately applied by the load pins 8, but the gas pressure inside the cap increases due to the sealing temperature and a predetermined time t1 (about 3 to 5 seconds) for allowing gas to escape from the resin portion. Later, a load is applied. Gel point B of thermosetting epoxy resin 2
Alternatively, the load pin 8 is removed after that, and the heating by the heating table 6 is stopped (the gel point B or the time after the application of the load is set to a predetermined time t2. In this example, the time is about 5 to 7 seconds or more. is there). This is shown in FIG. This completes the temporary bonding.

Next, in order to make the package 3 and the cap 1 have a sufficient adhesive strength (about 3 to 10 kg), place them in a thermostat at the state of FIG.
Cure for about 2 hours with no load to completely cure the thermosetting epoxy resin.

Further, in this embodiment, since the heating temperature of the resin in the temporary bonding is high and the gelation time is short, FIG.
As shown in the flowchart of (b), during the period from before the heating of the resin to the application of the load, the equipment stop request due to equipment abnormality or the like is prohibited, and the load is applied after the resin has passed the gel point B. Avoid that.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIGS. 5A to 5D are cross-sectional views in the order of steps of the second embodiment. The flowchart uses FIG. 2 of the first embodiment as it is.

Pellets 4 are mounted and bonding wires 5
Are connected on the lead frame, and the packages 3 are continuously sealed. FIG.
In (a), the first package 3 of the lead frame
Is transported to the sealing position 1 of the heating table and heats the sealed portion.
The temperature of the heating table is the glass transition temperature of the thermosetting epoxy resin (about 150 ° C).
As a higher temperature, a temperature at which the gel time becomes about 10 seconds is determined from the characteristic diagram of the resin in FIG. 4B (300 ° C. in this example).

Next, the cap 1 on which the thermosetting epoxy resin 2 is applied is sucked by the cap suction nozzle 7, and the cap 1 is lowered and placed on the bonding portion of the package 3. This is shown in FIG. The resin exhibits plasticity when heated, and fits into the sealed portion between the package 3 and the cap 1.
At this time, by placing the cap 1 on the package 3, the gas pressure inside the cap increases due to the sealing temperature, and after a predetermined time t1 (about 3 to 5 seconds) for allowing gas to escape from the resin portion, the lead frame is moved to the right (sealing). One piece is transported to the landing position 2). Figure 4 shows the resin of the first package transported.
Before reaching the gel point B shown in FIG.
And appropriate load on cap 1 (about 500-1500g)
Is added, the thermosetting epoxy resin 2 fits well into the bonding portion, and is formed so that reliable airtightness can be obtained. This is shown in FIG.

After the load is applied, at or after the gel point B, the load pins 8 are removed, and the lead frame is transported to the right side (sealing position 3) by one piece. From the table to an unheated table 9. This is shown in FIG. The gel point or the time after passing the gel point after applying the load is defined as a predetermined time t2. In this example, if the time for transporting one lead frame is 0.5 seconds, t
2 is about 4.5 to 6.5 seconds or more.

Further, in this example, the predetermined time t2 (about 4.5 to 6.5 seconds) is longer than the predetermined time t1 (about 3 to 5 seconds). However, in FIG. (From 0.5 to 3.5)
(Approximately seconds) to allow a predetermined time t2. This completes the first temporary bonding, but the second and subsequent packages are temporarily bonded in the same manner as the first.

After the temporary bonding, the resin is completely cured with no load curing in the same manner as in Example 1 while maintaining the lead frame shape.

In this embodiment, since the heating temperature of the resin in the temporary bonding is high and the gel time is short (about 10 seconds), the resin is heated as shown in the flowcharts of FIGS. 6 (a) and 6 (b). If there is a facility stop request due to equipment abnormality etc., make the equipment operate normally until the load is applied to the resin, stop the equipment after applying the load, and after the resin passes the gel point B Avoid applying loads.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIGS. 7A to 7D are cross-sectional views in the order of steps of the third embodiment. FIGS. 8A to 8C are timing charts of the heating temperature of the resin, the state of the resin, and the load on the resin. As shown in FIG. 7 (a), a plurality of packages 3 on which pellets 4 are mounted and connected by bonding wires 5 are connected in a lead frame shape. In 10 seconds), the caps 1 to which the thermosetting epoxy resin 2 has been applied are respectively bonded. In this state, the resin 2 is in the plastic region.

Next, the lead frame is conveyed to a heating table 6 as shown in FIG. 7 (b), and the plurality of packages 3, that is, the resin, are heated simultaneously. As for the temperature of the heating table, the heating temperature is the glass transition temperature of the thermosetting epoxy resin 2 (around 150 ° C.).
The temperature at which the gelation time becomes about 100 seconds as a higher temperature is determined from the characteristic diagram of the resin in FIG. 4B (180 ° C. in this example). After a predetermined time t1 (approximately 5 to 10 seconds) for releasing the gas from the resin portion due to an increase in the gas pressure inside the cap due to the heating temperature, the load pins 8 are not reached before reaching the gel point B shown in FIG. Then, an appropriate load (approximately 500 to 1500 g) is applied to each of the caps 1 so that the thermosetting epoxy resin 2 fits well into the bonding portion and is formed so as to obtain highly reliable airtightness. Figure 7
(C).

When the thermosetting epoxy resin 2 has reached or has passed the gel point B, the load pins 8 are removed, and the heating by the heating table 6 is stopped. The gel point B or the time after the application of the load after the application of the load is defined as a predetermined time t2. In this example, the time is about 90 to 80 seconds or more. This is shown in FIG. This completes the temporary bonding. After the temporary bonding, the resin is cured with no load for 1 to 2 hours as in Example 2, and completely cured.

In this embodiment, since the heating temperature of the resin in the temporary bonding is high and the gel time is short, FIG.
As shown in the flow chart of (b), when there is a facility stop request due to facility abnormality or the like before heating the resin and applying a load, the heating table 6 is lowered to stop heating the resin, and the resin is heated. Prevent curing and shut down equipment. After that, when returning to the equipment, the heating table 6 is raised and heated for a predetermined time t1.
Before reaching the gel point B shown in FIG.
To apply a load to the cap 4. In this way, applying a load after the resin has passed the gel point B is avoided.

[0025]

As described above, the present invention shortens the gel time by setting the heating temperature to the thermosetting epoxy resin at the time of temporary bonding to be higher than the glass transition temperature of the resin,
Also, at the time of equipment stop request due to equipment abnormality, etc., it is possible to shorten the sealing time of the temporary bonding step by avoiding applying a load after passing the gel point, it is possible to shorten the sealing time of the temporary bonding step, The productivity of the temporary bonding process has been increased, and no-load curing, which has been impossible in the past, is now possible. This eliminates the necessity of incorporating a load curing guide jig, which was conventionally required, and reduces the number of steps, thereby realizing the manufacture of an inexpensive semiconductor device.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, wherein FIGS.
(D) is sectional drawing of a manufacturing process.

FIGS. 2A to 2C are diagrams showing Embodiments 1 and 2 of the present invention, and FIGS. 2A to 2C are timing diagrams.

FIG. 3 is a diagram showing a first embodiment of the present invention, wherein FIG.
(B) is a flowchart respectively.

FIGS. 4A and 4B are diagrams showing characteristics of a thermosetting epoxy resin, and FIGS. 4A and 4B are temperature characteristic diagrams, respectively.

FIG. 5 is a view showing a second embodiment of the present invention, wherein FIGS.
(D) is sectional drawing of the order of a manufacturing process.

FIG. 6 is a view showing a second embodiment of the present invention, wherein FIG.
(B) is a flowchart respectively.

FIG. 7 is a view showing a third embodiment of the present invention, wherein FIGS.
(D) is sectional drawing of the order of a manufacturing process.

FIG. 8 is a view showing a third embodiment of the present invention, wherein FIGS.
(C) is a timing chart.

FIG. 9 is a view showing a third embodiment of the present invention, wherein FIG.
(B) is a flowchart respectively.

FIG. 10 is a view showing a conventional sealing method, and FIGS.
(D) is sectional drawing of the order of a manufacturing process.

FIG. 11 is a view showing a conventional sealing method, and FIGS.
(C) is a timing chart.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cap 2 Thermosetting epoxy resin 3 Package 4 Pellet 5 Bonding wire 6 Heating stand 7 Cap suction nozzle 8 Load pin 9 units 10, 11 Guide jig 12 Load spring A Point at which thermosetting epoxy resin shows plasticity B Thermosetting Gelation point of reactive epoxy resin C The point that thermosetting resin is thermoset and the adhesive strength of resin is sufficient

Claims (4)

(57) [Claims] 1. When a cap is bonded to a package on which a semiconductor device is mounted using a thermosetting epoxy resin, a point at which the plastic region ends before a point at which the plastic region of the resin ends while heating the resin. A method for sealing a semiconductor device in which a vertical pressure is applied to a cap surface, wherein the temperature for heating the resin is equal to or higher than the glass transition temperature of the resin. 2. The semiconductor device sealing method according to claim 1, wherein a stop request interrupt of the equipment is prohibited from immediately before heating the thermosetting epoxy resin until a vertical pressure is applied to the cap surface. . 3. The method according to claim 1, wherein when there is a request to stop the equipment while heating the thermosetting epoxy resin, a vertical pressure is applied to the cap surface before the end of the plastic region of the resin, and then the equipment is stopped. Item 7. The method for sealing a semiconductor device according to Item 1. 4. When there is a request to stop the equipment while heating the thermosetting epoxy resin, if the vertical pressure is not applied to the cap surface, the heating of the resin is stopped before the equipment is stopped. The method for sealing a semiconductor device according to claim 1.