JPH0722744A - Reflow soldering method for various kinds of components, and auxiliary tool for assembling components and reflow oven used in executing the method - Google Patents

Abstract

PURPOSE:To increase the void elimination effect within solder in reflow soldering. CONSTITUTION:A component assembly body where solder is included between components is supplied to a reflow oven 1 and a preheating process 1a, a solder melting process 1b, and a cooling process 1c are performed successively, and pressure applied to the component assembly body at the solder melting process 1b is changed, thus causing the void in the solder to be pushed out of the component assembly easily. The component assembly body is positioned at an auxiliary tool 2. In the component assembly auxiliary tool 2, a press part for applying pressure to the component assembly body is provided. The press part can be displaced freely in the direction of press and the press force can be changed according to the displacement. Also, a pressure reception part 13 which is linked to the press part is provided. In the reflow oven 1, a guide surface 15 where the pressure reception part 13 of the component assembly auxiliary tool 2 is provided corresponding to the part for performing the solder melting process 1b. When the pressure reception part 13 abuts on the guide surface 15, pressure applied to the component assembly body changes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering method in which a component assembly having solder between each component is supplied to a reflow furnace to sequentially perform a preheating step, a solder melting step and a cooling step, and a soldering method. The present invention relates to a component assembly auxiliary tool and a reflow furnace used directly for carrying out the method.

[0002]

2. Description of the Related Art Electronic components include, for example, a semiconductor silicon chip and components mounted on an insulating substrate via a heat sink. When joining them by soldering, as a preparatory step, the insulating substrate, each heat sink, and each component such as a semiconductor silicon chip are positioned on each jig of the component assembly auxiliary tool. In that case, the plate-like solder is placed on the insulating substrate and each heat sink. The insulating substrate, each heat sink, each component such as a semiconductor silicon chip, and each plate-shaped solder thus positioned in the component assembly auxiliary tool are polymerized with each other and preassembled to a product shape before solder melting, and Pressurized to ensure proper solder film thickness.

The electronic components thus assembled into the product shape by the component assembly auxiliary tool are supplied to the reflow furnace in the assembled state, and pass through the furnace while maintaining the assembled state. And then soldered.

Conventionally, as the pressurizing means, there has been one utilizing a weight as shown in, for example, Japanese Utility Model Laid-Open No. 1-109368.

[0005]

Generally, during reflow soldering, air bubbles and the like (hereinafter referred to as voids) may occur in the molten solder, resulting in defective joints.

Therefore, in view of the fact that the pressing force due to the weight is constant while the auxiliary tool for assembling parts is passing through the reflow furnace, the improvement of the pressurizing means is focused on to improve the void elimination effect. It is an invention.

[0007]

In the reflow soldering method according to the present invention, a component assembly in which solder is interposed between components is supplied to a reflow furnace to perform a preheating step, a solder melting step and a cooling step. The steps are sequentially performed, and the pressure applied to the component assembly in the solder melting step is changed. Therefore, the voids in the molten solder are easily pushed out of the component assembly.

In carrying out this method invention, the component assembly is positioned on the component assembly auxiliary tool according to the present invention. In this component assembly auxiliary tool, a pressurizing unit that applies pressure to the component assembly is provided. The pressurizing portion is displaceable in the pressurizing direction, and the displacement can change the pressurizing force.

Further, in this component assembly auxiliary tool, a pressure receiving portion which interlocks with the pressurizing portion is provided. In the reflow furnace used in carrying out the method invention,
A guide surface with which the pressure receiving portion of the component assembling assisting device abuts is provided corresponding to the portion where the solder melting step is performed. When the pressure receiving portion comes into contact with this guide surface, the pressure applied to the component assembly changes.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. A component assembly auxiliary tool 2 is supplied by a belt conveyor 3 into a reflow furnace 1 schematically shown in FIG. 1, and while the component assembly auxiliary tool 2 passes through the reflow furnace 1, a preheating step 1a and solder melting are performed. Soldering is performed by sequentially performing the process 1b and the cooling process 1c.

The above-mentioned component assembly auxiliary tool 2 schematically shown in FIG.
In the above, the component assembly 6 is provided between the upper jig 4 and the lower jig 5.
Is positioned. This component assembly 6 is an insulating substrate 7
The plate-shaped solder 8 and the bear chip 9 are placed on top of each other and laminated. The support 10 on the upper jig 4 is composed of a movable plate 10a, a bracket 10b, and a suspension rod 10c, and the movable plate 10a is fixed on the upper jig 4 by a compression coil spring 12 wound around the outer periphery of the support shaft 11. Supported. A bracket 10b on the movable plate 10a supports a pressure receiving portion 13 which is a rotating roller. The suspension rod 10 under the movable plate 10a
The pressure unit 14 is attached to c. The pressurizing portion 14 contacts the bare chip 9 and presses the bare chip 9 to the extent that it does not float. Then, when the pressure receiving portion 13 is pressed from above, the support body 10 moves downward in the pressing direction P against the elastic force of the compression coil spring 12, and the pressing portion 14 moves from above the bare chip 9 to the component assembly. Hold down 6 as a whole. On the other hand, when the pressure on the pressure receiving portion 13 is released, the support 1
0 moves upward due to the elastic force of the compression coil spring 12 and returns to the state of FIG.

In the reflow furnace 1, guide surfaces 15 are formed on the ceiling wall corresponding to the portions where the solder melting step 1b is to be performed so as to have an uneven shape alternately along the traveling direction of the component assembly aid 2. There is. A horizontal surface including the convex portion 15a of the guide surface 15 and the part assembly auxiliary tool 2 on the belt conveyor 3
Only G is provided as the difference in height between the pressure receiving portion 13 and the horizontal plane. Therefore, when the component assembly auxiliary tool 2 reaches the solder melting step 1b, the pressure receiving portion 13 periodically abuts on the convex portion 15a of the guide surface 15, and in the component assembly auxiliary tool 2, the pressurizing portion 14 is pressed. Repeated pressure is applied to the attachment 6. The magnitude of the pressing force and the timing of pressurization can be freely set by changing the guide surface 15 of the reflow furnace 1 or the side of the component assembly auxiliary tool 2.

In this way, when a pressure change occurs in the component assembly 6 in the solder melting step 1b, voids in the melted solder 8 are likely to be extruded, resulting in a good joining state. In the above-described embodiment, the uneven guide surface 15 is provided in the reflow furnace 1. Instead of the guide surface 15, permanent magnets are arranged at predetermined intervals along the traveling direction of the component assembly auxiliary tool 2, and Instead of the pressure receiving portion 13 of the component assembly auxiliary tool 2, a permanent magnet having the same pole as that of the permanent magnet may be attached, and the repulsive force between the permanent magnets may be used to similarly apply pressure.

Further, if an electromagnetic solenoid is mounted on the component assembly auxiliary tool 2 and the pressurization timing is changed by demagnetizing the auxiliary solenoid, pressurization control can be performed without providing the guide surface 15 in the reflow furnace 1.

In the above-described embodiment, the case where one bare chip 9 is soldered on the insulating substrate 7 has been exemplified, but the same applies to the case where a plurality of components are soldered on the insulating substrate 7.

[0016]

According to the reflow soldering method of the present invention, since a pressure change is applied to the component assembly in the solder melting step, voids are less likely to remain in the solder, and a good joining state is obtained. Further, according to the component assembly auxiliary tool and the reflow furnace according to the present invention, the component assembly can be easily pressurized, which is suitable for carrying out the method invention.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a reflow furnace according to the present embodiment.

FIG. 2 is a schematic cross-sectional view showing a component assembly auxiliary tool according to the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reflow furnace, 1a ... Preheating process, 1b ... Solder melting process, 1c ... Cooling process, 2 ... Component assembly auxiliary tool, 6 ... Component assembly, 8 ... Solder, 13 ... Pressure receiving part, 14 ... Pressurizing part , P ...
Pressure direction, 15 ... Guiding surface.

Claims (3)

[Claims] 1. A soldering method in which a component assembly having solder interposed between components is supplied to a reflow furnace to sequentially perform a preheating step, a solder melting step, and a cooling step, wherein the solder melting step comprises: A reflow soldering method for various parts, characterized in that the pressure applied to the assembly is changed. 2. A component assembly auxiliary tool for positioning a component assembly in which solder is interposed between each component, wherein a pressure portion for applying pressure to the component assembly is provided, and this pressure portion is used in a pressure direction. A tool for assembling parts during soldering, characterized in that it can be freely displaced to change the applied pressure. 3. A reflow furnace in which a component assembly auxiliary tool for positioning a component assembly having solder between each component is supplied to perform soldering through a preheating step, a solder melting step and a cooling step in order. A reflow furnace provided with a guide surface for changing a pressure applied to the component assembly by contacting a pressure receiving portion that interlocks with a pressure portion of the component assembly auxiliary tool according to claim 2.