JPH11340248A - Cover for heater rail - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce flowing in of an outside air without blocking bast operation, by providing a curtain of non-oxidizing gas blown upward at an opening surface through which a base material is accessed for bonding a semiconductor pellet of a cover for a heater rail wherein the base material is transported for heating. SOLUTION: When a semiconductor pellet is assembled while transported in a tunnel to a lead frame, the semiconductor pellet is supplied with non- oxidizing gas through a pellet supply hole 31 formed with a pellet supply hole 27c of a cover plate 27 and a pellet supply hole 25a of a hood 25 matching it. The non-oxidizing gas like inert gas which is adjusted for pressure independent of the inside of the tunnel is introduced into a gas introduction pipe 25 to fill a space 30, and blown from a slit 25b to constitute a gas curtain. The gas curtain is provided close to the end of the pellet supply hole 31, the outside air being prevented from entangled in the tunnel through the pellet supply hole 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a heater rail in which a base material is conveyed and heated when a semiconductor pellet is bonded to a base material such as a lead frame using a solder, and more particularly to an improvement in a hole provided in a cover. The present invention relates to a cover structure capable of keeping the atmosphere in a tunnel as a non-oxidizing atmosphere while minimizing the entrance of outside air.

[0002]

2. Description of the Related Art An example of a conventional heater rail will be described. FIG. 2A is a plan view thereof, and FIG. 2B is a side view showing a cross section taken along line AA in FIG. 2A. In the heater rail 1, a heat block 2 having a U-shaped cross section is arranged with its concave opening facing upward. A heater (not shown) is embedded in the heat block 2, and a dish-shaped adapter rail 4 covering almost the entire surface is disposed on the bottom surface of the concave portion 3 with the concave surface facing downward. Further, the heat block 2 is provided with a gas flow path from a gas introduction port 5 provided on the outer surface toward the bottom surface of the concave portion. Therefore, a space formed by the adapter rail 4 and the bottom surface of the concave portion of the heat block 2 serves as a tank 6 for storing the introduced gas. A cover plate 7 is attached to the upper surface of the heat block 2 so as to cover the recess 3, and the recess 3 forms a tunnel 3 a.

When assembling a semiconductor pellet (not shown) to a lead frame (not shown), the lead frame (not shown) is heated while being transported on the adapter rail 4 and solder (not shown) or semiconductor Pellets (not shown) are supplied and assembled. At this time, an inert gas such as nitrogen gas is introduced from the gas inlet 5 to prevent oxidation of the lead frame and the solder. The introduced inert gas fills the tank 6 and is blown into the tunnel 3a from gas outlets 4a provided around the adapter rail 4, and is discharged from the inlet and outlet of the tunnel 3a as a non-oxidizing atmosphere.

In order to make the inside of the tunnel a good atmosphere even with a flow rate of the inert gas as small as possible, the tunnel 3a is required.
The opening of the cover plate 7 is also required to be as small as possible because the opening of the
a, a hole 7b for stirring and spreading molten solder, and a pellet supply hole 7c for supplying semiconductor pellets. When the lead frame feed mechanism is provided in the tunnel 3a, the holes provided in the cover plate 7 may be only those described above.
Since the tunnel 3a becomes larger and the distance from the cover plate 7 to the lead frame becomes deeper, obstructing a high-speed supply of semiconductor pellets and complicating the mechanism, the lead frame is also transported from the outside. In such a case, a hole 7d for a conveying claw is provided as shown in FIG. The hole 7d for the transfer claw is also made as small as possible, and the transfer claw sends the lead frame by the square motion for each semiconductor device. At a place where the inert gas is discharged including these holes, a flow rate must be provided so that the outside air does not flow back into the tunnel 3a.

[0005] However, as shown in FIG.
For example, when the solder supply hole 7a is open, the inert gas is blown out from the hole 7a as shown by the solid line arrow to prevent the inflow of outside air. Although it is not a convection action, it can be estimated that the outside air is taken in as indicated by the broken line arrow, and there is a place where the oxygen concentration in the tunnel 3a cannot be sufficiently reduced. In view of this, the present applicant has previously provided a screen-like member 28 at the end of the hole 7a as shown in FIG. A proposal is made to take it out with an active gas (solid arrow). The screen-like member 28 preferably surrounds the opening in the form of a chimney. However, even if a part is inevitably missing for the purpose of the opening, there is a certain effect.

[0006]

However, when a partition member according to Japanese Patent Application No. 9-189519 is provided in the portion of the pellet supply hole 7c so as to surround the opening in a chimney shape, the semiconductor pellet is held in and out by vacuum suction. The operation path of the pellet transport mechanism becomes longer, which hinders speeding up of the chip bonder. In particular, since the pellet transport mechanism moves in and out of the pellet supply hole 7c at a high speed, the outside air is apt to be taken in, and it is necessary to make the chimney higher than the other parts. This further hinders the high-speed operation. Accordingly, the present invention provides a heater rail cover in which the inflow of outside air is reduced without hindering the high-speed operation of the device.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention forms a tunnel by covering a concave portion of a U-shaped cross section of a heat block, and a substrate is conveyed and heated in the tunnel. A heater rail cover having an opening for accessing the base material for bonding the semiconductor pellet to the base material, wherein the heater rail cover blows the edge of the opening in a direction perpendicular to the opening surface. Provided is a cover for a heater rail, which is provided with a gas curtain made of a reactive gas. According to the above configuration, the outside flow of the outside air into the tunnel is prevented by the gas curtain, so that even if there is something entering or exiting the opening, the movement is not hindered. In addition, there is also an effect that the outside air which is going to be taken in is washed off by the curtain gas. The gas curtain may be provided so as to surround the opening, or a screen-like member may be provided in a portion that is missing only on the side where an object enters and exits. Such an opening is particularly suitable for a place where objects enter and exit at a high speed, such as an opening for supplying semiconductor pellets.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to a portion corresponding to the pellet supply hole 7c of the conventional device shown in FIG. The heat block 2 is not different from the conventional apparatus shown in FIG. FIG. 1A is a perspective view thereof, and FIG. 1B is a side view showing a cross section taken along line AA in FIG. 1A. This heater rail cover 20
Has a structure in which a hood 25 is attached to a cover plate 27.

The cover plate 27 has a solder supply hole (not shown), a hole for stirring and spreading the melted solder (not shown), and a pellet supply hole 27c for supplying semiconductor pellets as in the prior art.

The hood 25 is provided with a pellet supply hole 25a aligned with the pellet supply hole 27c of the cover plate 27.
And a slit 25b so as to surround the pellet supply hole 25a. And, it is mounted on the upper surface of the cover plate 27 and forms a substantially airtight space 30 with the cover plate 27 except for the slit 25b. A gas introduction pipe 25c connected to the space 30 is provided on a side surface of the hood 25.

The heater rail cover 20 forms a tunnel by covering the recess opening of the heat block having a U-shaped cross section as in the conventional case. When assembling a semiconductor pellet (not shown) to a lead frame (not shown), the lead frame (not shown) is heated while being transported in a tunnel, and solder (not shown) or semiconductor pellet (not shown) is used. (Not shown) Supply and assemble. At this time, a non-oxidizing gas such as an inert gas such as nitrogen gas or a reducing gas to which hydrogen is added is introduced into the tunnel to prevent oxidation of the lead frame and the solder. Semiconductor pellets (not shown) are supplied through a pellet supply hole 31 formed by a pellet supply hole 27c of the cover plate 27 and a pellet supply hole 25a of the hood 25 matched with the hole. Pellet supply hole 3
From 1, part of the inert gas supplied into the tunnel is blown out as indicated by the solid line arrow to prevent outside air from entering the tunnel.

A non-oxidizing gas such as an inert gas whose pressure is adjusted independently of the inside of the tunnel is introduced into the gas introducing pipe 25, fills the space 30 and blows up from the slit 25b to form a gas curtain. Is done. Since this gas curtain is provided close to the end of the pellet supply hole 31, it prevents the outside air from being trapped in the tunnel through the pellet supply hole 31.

The gas curtain also has a function of cleaning and removing the outside air which is brought when the pellet transport mechanism (vacuum suction nozzle) holds the semiconductor pellets and enters the pellet supply hole 31 at high speed.

According to the above embodiment, the gas curtain is provided so as to surround the pellet supply hole 31. However, the gas curtain is provided only on the side through which the pellet transport mechanism passes when entering and exiting, and the rest is provided with a screen member. It is also possible to surround the pellet supply hole 31 together.

As described above, the present invention is effective when applied to a hole into which a high-speed material enters, such as a pellet supply hole, but is applicable to other holes such as a solder supply hole. It is.

[0016]

As described above, according to the present invention,
Since a gas curtain is provided at the end of the hole provided in the cover to prevent outside air from being drawn in from the hole, even if something goes in and out of the hole, the high-speed operation is not hindered. In addition, the non-oxidizing atmosphere in the tunnel of the heater rail can be secured by washing and removing the outside air that is taken in by the one entering the hole at high speed.

[Brief description of the drawings]

FIG. 1A is a perspective view of a heater rail cover using an embodiment of the present invention. FIG. 1B is a side view showing a cross section taken along line AA.

FIG. 2A is a plan view of a conventional heater rail. FIG. 2B is a side view showing a cross section taken along line AA.

FIG. 3 is a cross-sectional view illustrating a state in which outside air flows backward from a hole in a conventional cover plate.

FIG. 4 is a cross-sectional view showing a state in which a screen member is disposed as a countermeasure;

[Explanation of symbols]

 20 Cover for heater rail 25b Slit 31 Pellet supply hole (opening)

Claims (4)

[Claims] 1. A heater rail cover for covering a concave portion of a U-shaped cross section of a heat block to form a tunnel, in which a substrate is conveyed and heated in the tunnel, wherein the heater rail cover is An opening having access to the base material for bonding a semiconductor pellet to the base material, comprising a gas curtain made of a non-oxidizing gas blown in a direction perpendicular to an opening surface at an end of the opening. Cover for heater rail. 2. The heater rail cover according to claim 1, wherein said gas curtain surrounds said opening. 3. The heater rail cover according to claim 1, wherein the gas curtain is arranged so that a part of the periphery of the opening is partially cut off, and a screen-like member is arranged in the cut-out part. 4. The heater rail cover according to claim 2, wherein the opening is an opening for supplying a semiconductor pellet.