JPH0218950B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reducing atmosphere furnace for soldering used for chip mounts, connection of parts, etc.

[Prior art]

Traditionally, semiconductor products such as hybrid ICs are manufactured by first fixing the semiconductor to a printed circuit board using thermosetting resin, then performing wire bonding, and then soldering passive components such as resistors and capacitors.

When soldering passive components, the metal parts (copper parts) of the board are heated to high temperatures, so
Cream solder containing flux is usually used to prevent oxidation of that part.

However, one of the problems with this manufacturing method is that after soldering, cleaning and drying must be performed to remove flux.
There was a problem that production efficiency was reduced. In addition, some of the passive parts attached to the product have sliding parts, such as variable resistors, and if flux gets caught in those parts during cleaning, they may not function properly, or painted parts may There are some items that are not suitable for cleaning, such as those that disappear when washed.

Therefore, recently, a soldering bonding method has been implemented in which passive components are soldered using a reducing atmosphere furnace instead of flux-cored solder and does not require subsequent cleaning work. That is,
After wire bonding is completed, the board with passive components placed in the required locations is placed on a conveyor belt and placed in a reducing atmosphere furnace, where it is indirectly heated by the high temperature reducing atmosphere that fills the interior, and soldering is performed. This is what we are trying to do.

[Problem that the invention seeks to solve]

However, when attempting to solder using such a reducing atmosphere furnace, hydrogen gas is normally used as the reducing atmosphere, and heating during solder bonding is indirect heating by the atmosphere. This makes it difficult to control the heating temperature.
Therefore, a large furnace of about 8 to 10 meters was usually required. Additionally, in addition to requiring equipment to indirectly heat the atmosphere to a high temperature, after soldering is completed, the product is cooled by the atmosphere in the furnace, so cooling equipment is also required to indirectly cool the atmosphere. This led to an increase in costs. Furthermore, the larger the furnace capacity, the longer the working time required for indirect heating and indirect cooling, and the higher the running cost, which leads to a decrease in productivity.

The present invention was devised in view of the above-mentioned problems, and aims to solve the above-mentioned problems by fundamentally improving the above-mentioned reducing atmosphere furnace.

[Means for solving problems]

FIG. 1 is a schematic diagram showing the basic configuration of a reducing atmosphere furnace for soldering according to the present invention. Here, the furnace of the present invention includes a direct heating bed 1, a direct cooling bed 2 continuous to the direct heating bed 1, a reduction box 3 provided above the direct heating bed 1, and a pusher provided on the inlet side of the direct heating bed 1. It consists of 4.

The direct heating bed 1 includes a product 10 such as an electric heater.
A device that can directly heat the product 100 and control the heating temperature is used, and has a floor-like structure on which the product 100 can be placed and moved.

In addition, the direct cooling bed 2 is used to cool the product 1 like a water cooling device.
00, which can be directly cooled and whose cooling temperature can be controlled, has a floor-like structure on which the product 100 can be placed and moved, similar to the heating bed 1 described above.

Furthermore, the reduction box 3 is installed so as to directly cover the heating bed 1, and is a facility that fills the inside with a reducing atmosphere and prevents oxidation while the product 100 is being heated.

Since the pusher 4 is provided with the direct heating bed 1 and the direct cooling bed 2 as a path for placing and moving the product 100, the product 100 is directly transferred from the input side of the heating bed 1 into the reduction box 3 instead of using the conventional conveyor belt. It is directly pushed out toward the exit side of the cooling bed 2 through the cooling bed 2.

[Effect]

In the furnace having the above configuration, after wire bonding is completed, the semiconductor product 100 mounted with passive components and solder for bonding them is directly transferred from the entry side of the heating bed 1 into the reduction box 3 by the pusher 4. It is extruded and directly heated by a heating bed 1 in a reducing atmosphere. At this time, the direct heating bed 1 performs heating while controlling its heating temperature. In this way product 1
After the product 100 is soldered, the pusher 4 pushes the product 100 directly to the cooling bed 2, where it is cooled.

〔Example〕

FIG. 2 is a side view showing an embodiment of the reducing atmosphere furnace of the present invention. Of these, 10 indicates a direct heating bed, 20 indicates a direct cooling bed, 30 indicates a reduction box, and 40 indicates a pusher.

The above-mentioned directly heated bed 10, as shown in FIG.
A plurality of electric heaters 12 are installed in the inner width direction of a stainless steel frame 11, and a perforated stainless steel plate 13 shown in the figure is arranged so as to be in contact with the upper surface of these electric heaters 12. When the product 100 is transferred onto the product movement guide rails 14a and 14b laid on the product movement guide rails 14a and 14b, the product 100 is directly heated by the electric heater 12. In this way, since the direct heating bed 10 directly heats the product 100 using the electric heater 12, the heating temperature can be quickly adjusted to the optimum temperature (approximately 350° C.).

Further, the direct cooling bed 20 is provided continuously with the direct heating bed 10, and its structure is as shown in FIG. A cooling water channel 22 is provided, and silicon rubber (not shown) is provided on the upper open side of the cooling water channel 22.
Guide rails 24a, 24b for moving products through
The perforated stainless steel plate 2 shown in Fig. b is laid with
3 is installed. Cooling water cooled by a radiator 26 is circulated in the cooling water channel 22 by a pump 25.
When the product 100 on which soldering has been completed is transferred, it is cooled. In this way, the direct cooling bed 20 directly cools the product 100 by circulating the cooling water while being cooled by the radiator 26, so that rapid cooling can be achieved.

Further, the reduction box 30 is directly connected to the heating bed 10.
It is a closed box-shaped thing arranged to cover the upper part, and a hydrogen gas inlet 31 is provided at the top, and an introduction pipe 32 is connected to it from a hydrogen gas source (not shown). The interior of the box 30 is filled with a reducing atmosphere due to the injection of hydrogen gas. In addition, entrances and exits 33 and 34 for conveying the product 100 are provided on the side wall surface of the reduction box 30 along the length direction of the direct heating bed 10 and the direct cooling bed 20, and an air curtain-like N ₂ gas flows and creates a gas shield, preventing atmospheric air from entering the interior.

The pusher 40 is directly connected to the heating bed 10.
Provided on the outside of the entry side, the contact surface 4 is provided at the tip of the rod 42.
The product 100 is directly transported from the input side of the heating bed 10 to the reduction box 3.
This is a device that directly pushes the cooling bed 20 toward the exit side through the interior of the cooling bed 20.

The reducing atmosphere furnace of this embodiment having the above configuration is used in the following manner. First, after wire bonding is completed, a semiconductor product 100 is mounted with passive components and solder for bonding them.
The guide rails 14a, 1 on the inlet side of the directly heated bed 10
Place it on 4b. Then, the contact surface 43 of the pusher 40 is applied to the product 100 and the guide rail 14 is pressed against the product 100.
a, 14b, and slowly transferred into the reduction box 30 from the inlet 34. Then, product 1 is removed inside the reduction box 30 filled with hydrogen gas.
00 moves on the stainless steel plate 13 of the direct heating bed 10, so the electric heater 1 of the direct heating bed 10
2, it is directly heated and the temperature quickly rises to about 350°C. In this way, the product 100 is soldered while moving directly on the heating bed 10, and during this time the soldered part is reduced by hydrogen gas, so that passive components can be connected quickly and reliably. It will be done. Further, the product 100 is passed through the outlet 35 by the pusher 40 to the return box 3.
Once pushed outside, the product 100 moves directly onto the cooling bed 20 along the guide rails 24a, 24b, where it is rapidly cooled.

〔Effect of the invention〕

As explained above, according to the reducing atmosphere furnace of the present invention, heating and cooling of the product is performed by direct heating and cooling using a direct heating bed and a direct cooling bed, instead of indirect heating and cooling using a reducing atmosphere. Since the heating temperature is easily controlled, heating and cooling can be performed quickly, and the entire device can be made compact to about 1 m, which is an excellent effect. In addition, as mentioned above, instead of indirect heating and cooling using the atmosphere, heating and cooling are performed using a direct heating bed and a direct cooling bed, which eliminates the need for atmosphere heating and cooling equipment, reducing equipment costs. Along with being able to
It also has the advantage that the working time required for heating and cooling can be shortened and running costs can be reduced, thereby improving productivity.

The reducing atmosphere furnace of the present invention can also be used to prevent bubbles from forming on the bonding surface when soldering items that require a large bonding area, such as large-capacity diodes and thyristors. can.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the basic configuration of the present invention, Figure 2 is a schematic diagram showing the basic configuration of the present invention.
The figure is a side view showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing the configuration of a direct heating bed in the embodiment.
FIGS. 4a and 4b are explanatory diagrams similarly showing the structure of the direct cooling bed. In the figure, 1 and 10 are direct heating beds, 2 and 20 are direct cooling beds, 3 and 30 are reduction boxes, 4 and 40 are pushers, and 100 is a semiconductor product.

Claims (1)

[Claims] 1. A direct heating bed, a direct cooling bed provided in continuation with the direct heating bed, a reduction box installed above the direct heating bed and filled with a reducing atmosphere, and a reduction box for transporting the product from the entry side of the direct heating bed. A reducing atmosphere furnace for soldering, characterized in that it has a pusher that pushes the cooling bed directly through the interior toward the exit side of the cooling bed.