JP2000022014A - Heater of pressure reduced oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation in quality or reliability of a product by preventing the sealing of a nichrome wire vapor, etc., in a package in a heater of a pressure reduced oven used for heating-drying the package body as for the prestep of airtight sealing a semiconductor element in the package. SOLUTION: In the heater of a pressure reduced oven, a pair of right and left heater blocks 50 are heated by a plurality of halogen heaters 72 while a self board 52 held between both heater blocks 50 is heated by the conductive heat from the heater blocks 50. In such an arrangement, it is recommended that the halogen heaters 72 are horizontally supported in a plurality of positions in a heater chamber 58 to be expanded in the long direction of the heaters 72. The halogen heaters 72 can be loaded on a pair of heater supporting members 80 fixed on an insertable reflecting board into the heater chamber 58 to be suspended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduced pressure used for heating and drying a package body on which a semiconductor element is mounted under a reduced pressure atmosphere as a pre-process of welding a cap to a package body containing a semiconductor element and hermetically sealing the same. The present invention relates to a heater device for an oven.

[0002]

2. Description of the Related Art It is known that semiconductor devices such as ICs, hybrid ICs, and CCD devices are hermetically sealed in a ceramic package or a metal package. In a ceramic package, a frame-shaped metal seal frame is joined to a ceramic substrate, and a metal cap (lid, lid) is joined to the seal frame. In a metal package, a ceramic substrate on which a semiconductor element is mounted is fixed in a metal package body, and a metal cap is joined to the package body. Here, the lead passes through a small hole provided in the package body, and is sealed with glass in this small hole.

As described above, when a cap is welded to a ceramic package body or a metal package body to which a seal frame is joined, the package body is heated under reduced pressure prior to welding of the cap. It is necessary to dry. That is, various gases (especially moisture) are adsorbed to the package body before the cap welding while the semiconductor element is mounted or the internal wiring is performed inside the package body, or during the standby until the next cap welding step. .

If the cap is welded and sealed with the adsorbed gas or moisture as it is, these gases remain in the package, and the reliability of the product is reduced. Therefore, immediately before welding the cap, the package body containing the semiconductor element in advance is placed in a reduced-pressure oven, and the adsorbed gas is removed by heating under reduced pressure, and immediately thereafter, an inert gas such as nitrogen (N ₂ ) is used. The cap is welded and sealed in the atmosphere.

A heater using a nichrome wire heater is known as a heater for a vacuum oven used here. In this heater device, a nichrome wire heater is attached to a shelf provided in an airtight chamber, and a carrier holding many package bodies is placed on the shelf to heat many package bodies simultaneously under reduced pressure. It is.
In this case, since the uniformity of the temperature distribution over the entire shelf plate is deteriorated, the nonuniformity of the heating temperature among a large number of package bodies is increased, and there is a problem that the quality of the products is greatly varied.

It is conceivable to increase the number of heaters used in order to improve the uniformity of the temperature distribution. However, in this case, many expensive heaters are required and the structure becomes complicated. Therefore, instead of mounting the nichrome wire heater on the shelf itself, the applicant of the present application provides a pair of heater blocks heated by the nichrome wire heater on both sides of the shelf, and hangs a copper shelf between the two heater blocks. It has been proposed to fix the heater block and to conduct heat from the heater block to the shelf board by heat conduction (Japanese Patent Laid-Open No. 9-61054).

[0007]

Problems with the prior art As described above, in the proposed heater device of the decompression oven in which the heat of the heater block heated by the nichrome wire heater is transmitted to the copper shelf plate,
When the heating temperature is relatively low (for example, about 200 ° C. or less), no major problem occurs, but when the heating temperature is high (for example, about 300 ° C.), the following problem occurs.

That is, since the heater used here is not sealed with a nichrome wire, there is a problem that the evaporation of the nichrome wire is promoted when the temperature of the heater is increased under reduced pressure. The vaporized molecule (vapor) of this nichrome wire
Is left in the package, which is one of the causes of a decrease in product reliability. Also, since a voltage is applied to the nichrome wire heater under reduced pressure, a discharge phenomenon may occur between the nichrome wire and surrounding members (such as a heater block). When this discharge occurs, evaporation of the nichrome wire is further promoted.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when a shelf board stretched between a pair of left and right heater blocks is heated by heat conduction from the heater blocks, evaporation of the nichrome wire is prevented. It is an object of the present invention to provide a heater device for a reduced-pressure oven, which does not cause the evaporation of the nichrome wire due to the discharge of the nichrome wire and does not cause a decrease in the quality and reliability of the product.

[0010]

According to the present invention, it is an object of the present invention to provide a package body containing a semiconductor element as a pre-process for welding a cap to a package body containing a semiconductor element and hermetically sealing the semiconductor element in a package. In a heater device of a reduced pressure oven used for drying and heating under a reduced pressure atmosphere, a sealable chamber, a pair of left and right heater blocks housed in the chamber, and a plurality of halogen heaters attached to these heater blocks And a shelf plate with good thermal conductivity that is bridged between both heater blocks and heated by conduction heat from these heater blocks, and a carrier with good thermal conductivity holding a plurality of the package bodies on the upper surface is provided. A heater device for a vacuum oven, which can be placed on a shelf,
Is achieved by

Here, the halogen heater is housed in a heater housing chamber formed horizontally in the heater block, and has a structure in which the halogen heater is supported at a plurality of locations to allow expansion and contraction in the longitudinal direction due to a temperature change of the halogen heater. Good to do. If a pair of heater supports are fixed to a reflector plate that can be inserted into and removed from one end of this heater storage chamber and both ends of the halogen heater are supported by this heater support member, the heater is pulled out together with the reflector plate and the heater is replaced. Work such as cleaning and cleaning becomes easy.

If the tray can be placed on the shelf and the carrier holding the package body can be placed on the tray and set on the shelf, the workability is improved. The heater block is formed of an aluminum heater block main body and a copper inner plate closely fixed to the inner surface thereof, and a heater recess is formed by the horizontal recess formed in the heater block main body and the inner plate. Can be. In this case, it is desirable that the surface of the inner plate, especially the surface on the side of the heater accommodating chamber, be blackened by plating or painting in order to easily absorb the heat of the halogen heater.

[0013]

FIG. 1 is a perspective view showing a heater device according to an embodiment of the present invention, FIG.
3 is a sectional view taken along line III-III in FIG. 2, FIG. 4 is a sectional view taken along line IV-IV in FIG. 2, FIG. 5 is a perspective view showing a supporting structure of the halogen heater, and FIG. It is a plane arrangement view of an automatic seam welding device.

First, an outline of the package sealing step will be described with reference to FIG. In FIG. 6, reference numeral 10 denotes a vacuum oven according to the present invention. The oven 10 includes a sealable chamber 12 and a heater device 14 housed therein. The left and right sides of the chamber 12 in the figure can be opened and closed by shutters 12a and 12b, respectively. The chamber 12 is connected to a vacuum pump (not shown) via a pipe 12c to reduce the pressure inside. An inert gas such as nitrogen gas (N ₂ ) can be supplied to the chamber 12 via a pipe 12d.

In the chamber 12, one of the shutters 12a is opened, and the package body is put in. That is, a plurality of package bodies on which semiconductor elements are mounted are held on a carrier 102 (see FIG. 1) described later, and
The tray 104 (see FIG. 1) on which a plurality of sheets 02 are placed is set in the heater device 14. The shutter 12a is closed to reduce the pressure in the chamber 12, and heating (baking) by the heater device 14 is started.

Thereafter, heating is stopped for a predetermined time in a state where the pressure in the chamber 12 is reduced, and then heating is stopped, and nitrogen gas is supplied into the chamber 12. In this automatic seam welding equipment,
In FIG. 6, a portion on the right side of the right side of the chamber 12 is covered with a box-shaped hermetic case, and the inside of the hermetic case is kept in a nitrogen gas atmosphere at substantially atmospheric pressure.

When the nitrogen gas pressure in the chamber 12 becomes substantially equal to the internal pressure of the airtight case, the right shutter 1
2b is opened by automatic operation, and the carrier retraction unit 16 takes in the carrier 102 and transfers it to the buffer 18.
The carrier 102 transferred to the buffer 18 is transferred to the tacking station 20, where a cap (lid, metal lid) is temporarily fixed to each package body 100 on the carrier 102.

That is, in the temporary attachment station 20, the cap adsorbed on the suction head from the cap supply section 20a is correctly positioned with respect to the package body by using a CCD camera, and between the electrodes contacting at two places on the joining edge. A welding current is applied to temporarily attach. The package body with the cap temporarily attached is Y seam station 22 and X
It is sequentially sent to the seam station 24, and is seam-welded by a pair of micro-roller electrodes that roll on the joining edge, respectively (referred to as micro-parallel seam welding).

If there is a defective package during this time, it is discharged by the discharge unit 26. The package (finished product) in which the cap is correctly seam-welded is taken out by the unloader 28 and collected in the stocker 30. When a certain amount of packages (finished products) are collected in the stocker 30, the door 32 of the airtight case is opened and taken out. There is a partition wall between the X seam station 24 and the unloader 28, and the package is transferred to the unloader 28 by opening the shutter 34. This shutter 34
Opens the door 32 and puts the package (finished product) on the stocker 3
By closing it when taking it out from 0, outside air is prevented from entering the airtight case surrounding each of the stations 20, 22, 24.

Next, the heater device 14 housed in the vacuum oven 10 will be described with reference to FIGS. As is apparent from FIGS. 1 and 2, the heater device 14 includes a pair of left and right heater blocks 50 and a plurality of copper thick plate shelves 52 bridged between the two heater blocks 50. The heater block 50 is formed by closely attaching an inner plate 56 made of copper to an inner surface of a heater block body 54 made of aluminum, and three horizontal heater storage chambers 58 are formed between the two.

That is, the heater block main body 54 is formed with three horizontal concave portions 60 opened toward the inner plate 56, and the concave portion 60 and the inner plate 56 form a heater accommodating chamber 58. At least a portion of the inner plate 56 facing the recess 60 is preferably colored black with black plating or black paint to improve the heat absorption efficiency of the halogen heater 72 described later.

A copper spacer 62 sandwiching the edge of each shelf 52 from above and below is in close contact with the inner surface of the inner plate 56. That is, the spacer 62 and the edge of the shelf plate 52 are alternately overlapped, and the upper plate 64 and the bottom plate 66 are further overlapped and fastened and joined by four long bolts 68 penetrating these vertically. A bolt 70 (FIG. 2) penetrating through the inner plate 56 from the heater block main body 54 side is screwed into an appropriate spacer 62. As a result, the heater block main body 54, the inner plate 56, and the spacer 62 are in close contact with each other, the edges of the shelf plate 52 are in close contact with the upper and lower spacers 62, and the heat of the heater block 50 is transferred to the shelf plate 52. It is transmitted smoothly.

A halogen heater 72 is accommodated in each heater accommodating chamber 58 of the heater block 50. The halogen heater 72 uses light (mainly infrared light) emitted from a halogen lamp as heat, and uses a filament having a small heat capacity as a heat source, so that the response of generated thermal energy to ON / OFF of a filament current is good. As shown in FIG. 5, the halogen heater 72 is formed by sealing a filament in a rod-shaped glass case, and has a square base 74 formed by crushing the glass case at both ends.

In the heater storage chamber 58, a stainless steel reflecting plate 76 which is in close contact with the inner surface of the recess 60 on the side of the heater block main body 54 is mounted so as to be inserted from one opening of the heater storage chamber 58. . In FIG. 5, 7
Reference numeral 8 denotes a knob formed at one end of the reflection plate 76. The knob 78 is used when the reflection plate 76 is moved in and out of the heater accommodating chamber 58.

On the inner surface of the reflector 76, a pair of heater supporting members 8 for supporting the corner base 74 of the halogen heater 72 is provided.
0 is fixed. As shown in FIG. 5, a cutout groove 82 that opens upward is formed in the heater support member 80, and the square base 78 is engaged with the cutout groove 82 from above. Therefore, expansion and contraction of the glass case due to a temperature change of the halogen heater 72 is accommodated by sliding the corner base 78 in the notch groove 82 in the length direction.

The lead wires 84 of the halogen heater 72 extend outward from the corner bases 74 at both ends. One lead wire 84 is connected to a terminal 88 of an insulating terminal plate 86 fixed to the outer surface of the heater block main body 54. The other lead wire 84 is folded back, passes through the inside of the heater accommodating chamber 58, and is connected to another terminal 88 of the terminal plate 86. An appropriate number of ceramic heat-resistant protective tubes are attached to the lead wires 84.

In FIGS. 1, 2, and 4, reference numeral 90 denotes a cooling block fixed to the outer surface of the heater block main body 54. The cooling block 90 has a passage 92 formed therein.
The heater block 50 is cooled from the outside by passing a cooling liquid through the heater block 50. An auxiliary shelf 94 made of a stainless steel plate is screwed to the upper surface of each shelf 52. The auxiliary shelf 94 prevents the copper shelf 52 from being worn. Behind the shelf 52, a single rod-shaped stopper 96 passes vertically through the center of the shelf 52 in the width direction.
6 is held.

The heater device 14 configured as described above
Has a rod-shaped stopper 96 at the back of the shelf 94,
The tray 104 is taken in and out from the front side (the side opposite to the stopper 96). This heater device 14 is shown in FIG.
When used in combination with the above device, the rod-shaped stopper 9
6 may be changed to the shutter 12b. The heater device 14 from which the stopper 96 has been removed as described above has the front surface facing the shutter 12a in FIG.
It is accommodated in the chamber 12 toward the 2b side. The package body 100 (FIG. 1) with the top open before the cap welding is
A plurality of carriers 102 are held by a stainless steel carrier 102, and the plurality of carriers 102 are put on a tray 104 made of a stainless steel plate and stand by.

The operator opens the shutter 12a, manually inserts the tray 104 into the auxiliary shelf board 94 on the shelf board 52 sequentially, and applies the tray 104 to a stopper (not shown) attached to the shutter 12b. Positioning and shutter 12a
Close. Next, the pressure in the chamber 12 is reduced, and heating by the halogen heater 72 is started. Heating under reduced pressure is continued for a predetermined time. The heating current of the halogen heater 72 is controlled by, for example, a phase control method to control the temperature. In this case, a thermocouple 106 (see FIGS. 1 and 2) is attached to the front end face of the spacer 62 closest to each halogen heater 72, and the detected temperature of each thermocouple 106 is set to the current of each halogen heater 72. Negative feedback.

When the heating and drying (baking) of the package body 100 is completed in this manner, nitrogen gas is supplied into the chamber 12, the shutter 12b is opened, the draw-in unit 16 automatically draws out the tray 104, and the buffer 18
Transfer to Thereafter, the cap is temporarily attached as described above, and parallel seam welding in the Y direction and the X direction using the micro roller electrode is performed.

According to this embodiment, the halogen heater 7
In No. 2, since both ends are placed on and supported by the heater support member 80 fixed to the reflection plate 76, expansion and contraction of the halogen heater can be allowed. Generally, the glass heater itself is hardly heated by the light because the light (infrared ray) passes through the glass case. However, when the halogen heater 72 is used in a high-temperature atmosphere in the heater device 14 as in this embodiment, Since the temperature change width of the glass case becomes large, it is necessary to consider a supporting structure so as to allow the glass case to expand and contract.

[0032]

According to the first aspect of the present invention, as described above, a pair of left and right heater blocks are heated by a plurality of halogen heaters, and a shelf plate held between the two heater blocks is transferred from the heater block by heat conduction. In this case, no evaporation of the nichrome wire occurs, no discharge of the nichrome wire occurs, and it is possible to prevent harmful components from entering the package during hermetic sealing of the package. For this reason, the reliability of the product can be improved.

The halogen heater has a smaller heating capacity than the nichrome wire heater because of its small heat capacity.
Responsiveness of cooling is extremely good, and is generally considered to be 1.5 to 3.0 times better. In addition, in the case of a nichrome wire heater, heating is performed mainly by heat transfer due to convection of gas, whereas in the case of a halogen heater, heating is performed by radiation of light (infrared rays), so that heating can be performed efficiently even under reduced pressure. For this reason, according to the present invention, since heating can be performed efficiently and responsively even under reduced pressure, the effect of shortening the baking processing time and increasing the tact (the processing amount within a certain time) can be obtained.

Here, the heater block is provided with a horizontal heater accommodating chamber, in which a halogen heater is horizontally supported at a plurality of locations to allow expansion and contraction in the longitudinal direction. This can absorb expansion and contraction of the halogen heater due to a temperature change, and can prevent an unreasonable stress from being applied to the halogen heater. In this case, if the halogen heater is configured so that it is mounted on a pair of heater supports fixed to a reflector that can be inserted into the heater accommodating chamber and is hung, inspection and maintenance of the halogen heater can be performed by extracting the reflector. The workability is improved (claim 3).

If a carrier holding a plurality of package bodies is placed on a tray and this tray is placed on the upper surface of the shelf and heated, the heat of the shelf is further diffused by the tray and the heating temperature of each package body is increased. Is made more uniform (claim 4). If an auxiliary shelf such as a stainless steel plate is fixed to the top of the shelf here, the heating temperature will be even more uniform, and if the shelf is made of a soft metal such as copper, the shelf will be protected from abrasion. be able to.

The heater block is formed of an aluminum heater block main body and a copper inner plate closely attached to the inner surface thereof, and is provided between a horizontal recess formed on the heater block main body side and the inner plate. A heater accommodating chamber can be formed (claim 5). In this case, not only is it easier to fabricate the heater chamber, but also to make the inner plate at least a part facing the heater chamber black, so that the radiant heat of the heater can be more efficiently absorbed by the inner panel. It will be easier.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a front view in which a part is similarly sectioned.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a perspective view showing a supporting configuration of a halogen heater.

FIG. 6 is a diagram showing an example of use of a vacuum oven.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Decompression oven 12 Chamber 14 Heater device 50 Heater block 52 Shelf plate 54 Heater block main body 56 Inner plate 58 Heater accommodation room 60 Depression 62 Spacer 64 Upper plate 66 Bottom plate 72 Halogen heater 74 Square base 76 Reflector 80 Heater support 94 Auxiliary shelf 100 Package body 102 Carrier 104 Tray

Claims (5)

[Claims] 1. A package body containing a semiconductor element is dried and heated under a reduced pressure atmosphere as a step before welding a cap to a package body containing a semiconductor element to hermetically seal the semiconductor element in a package. In the heater device of the vacuum oven used for this purpose, a sealable chamber, a pair of left and right heater blocks housed in the chamber, a plurality of halogen heaters attached to these heater blocks, and a bridge between the heater blocks. And a shelf plate having good heat conductivity heated by conduction heat from these heater blocks, and a carrier having good heat conductivity holding a plurality of the package bodies on the upper surface can be placed on the shelf plate. A heater device for a vacuum oven characterized by the following. 2. The heater block according to claim 1, wherein a horizontal heater accommodating chamber is formed in the heater block, and the halogen heater is horizontally supported at a plurality of locations in the heater accommodating chamber and is capable of extending and contracting in its length direction. Heating device for vacuum oven. 3. A heater accommodating chamber is provided with a reflector which can be inserted and withdrawn from one end and opens toward the shelf in front view, and both ends of the halogen heater are mounted on a pair of heater supports fixed to the reflector. 3. The heater device for a vacuum oven according to claim 2, wherein said heater device is stopped. 4. The apparatus according to claim 1, further comprising a tray mounted on an upper surface of said shelf, wherein said carrier is mounted on said tray.
3. A heater device for a vacuum oven according to any one of (3). 5. The heater block is tightly fixed to an inner surface of the heater block body so as to cover the aluminum heater block body having a horizontal recess formed on the shelf board side and the recess. 4. The heater device for a decompression chamber according to claim 2, further comprising a copper inner plate, wherein the heater accommodating chamber is formed by the concave portion and the inner plate.