JPH084932B2 - Reflow soldering machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wiring / connecting device for various electromechanical products, and in particular, a heating chip is pressed against a soldered portion to melt the solder and connect a thin coated wire. The present invention relates to a reflow soldering device.

[Conventional technology]

Reflow type soldering is a technique of interposing solder between the parts to be soldered to be joined and melting the solder by heating to perform metal joining, but in this method,
Variations in heating chip temperature and variations in solder amount
It affects the quality of solder joints and shortens the soldering time.

Therefore, as a solution to this problem, a conventional method, for example, Japanese Patent Laid-Open No. 62-
As described in Japanese Patent No. 172791, an adaptive control type soldering method has been proposed in which the supply time of a heating current is controlled according to the actual degree of melting of solder in a soldered portion.

[Problems to be Solved by the Invention]

In the conventional reflow soldering device, it is difficult to perform soldering of sufficiently good quality because it detects the melting degree of the solder and stops the heating current, that is, controls the heating time. There was a problem.

More specifically, in the conventional reflow soldering apparatus, even if the heating time is controlled according to the melting degree of the solder, the heating tip has a higher temperature than the solder and usually has a higher heat capacity than the solder. However, there was a problem that the temperature of the solder became unnecessarily high and the following description was made.

(1) The cooling rate of the solder becomes slow and oxidation progresses.

(2) Solder cooling time is required, which hinders reduction of takt time.

(3) Not only the crystal grains of the solder are coarsened, but also the thickness of the alloy layer formed between the soldered component and the solder is increased to reduce the soldering strength.

It is an object of the present invention to provide a reflow type soldering device that enables high-quality solder bonding and shortens the time required for soldering work.

[Means for solving the problem]

In order to achieve the above object, in the reflow soldering apparatus of the present invention, a heating chip for melting the solder of the soldered portion, a power supply means for supplying power to the heating chip to generate heat, and a heating chip. Moving means for contacting and pressing the part to be soldered and separating it, a conduction detecting means for detecting conduction between the heating chip and the coated thin wire or the coated thin wire and the circuit pattern, and the heating chip When the heating chip and the covering thin wire or the covering thin wire and the circuit pattern are electrically connected to each other, the power is supplied to the heating chip at a predetermined timing after being pressed to the start timing setting means. And means for controlling the amount of electric power supplied from the means to the heating chip.

[Work]

In the reflow soldering device, when power is supplied to the heating tip, the heat of the heating tip is conducted to the portion to be soldered through the thin coating wire interposed between the heating tip and the portion to be soldered.

At this time, the coated thin wire is usually a copper core wire coated with a resin, but the thermal conductivity coefficient of this resin is
It is lower than that of solder.

Further, since the contact area between the thin resin wire, the heating chip and the soldered portion is narrowed, it is difficult for heat to be conducted to the soldered portion.

Therefore, before and after the coating of the coated thin wire melts,
The amount of heat conduction from the heating tip to the soldered part changes.

Therefore, in the reflow soldering apparatus of the present invention, before the coating of the coated thin wire is melted, the amount of electric power to the heating tip is increased to heat the heating tip to a high temperature, and after the coating of the coated thin wire is melted, heating is performed. By lowering the amount of electric power to the chip and lowering the heating temperature of the heating chip, control of the soldered portion is facilitated and the quality of the solder is stabilized.

〔Example〕

Hereinafter, FIGS. 1 to 3 showing a reflow soldering apparatus according to an embodiment of the present invention will be described.

As shown in FIG. 1, a heating head 2 is attached to the lower portion of the welding head 1, and the heating tip 2 is formed of a material, such as tungsten, which generates heat by supplying electric power. Further, the heating chip 2 has a portion to be soldered, for example, a covered thin wire 7 and a circuit board 8 installed on the workbench 9 below the heating tip 2,
An appropriate amount of solder 10 is interposed between the 8's.

On the other hand, the welding head 1 is fixed to the linear table 4 via the welding arm 3. This linear table 4
It is installed to slide the welding arm 3 along the base plate 6 in the vertical direction. A stopper 5 fixed to the upper end surface of the base plate 6 to determine the end point position above the welding head 1 is installed above the linear table 4.

The moving means 11 moves the welding head 1.
In this moving means 11, when a lever 1103 rotatably supported by a linear table 1101 via a shaft 1102 is rotated, a pin 1104 fixed to one end thereof has a long hole 1105.
The rotary motion is converted into a linear motion via 06, and the welding head 1 is moved in the vertical direction via the linear table 4. A weight 1107 is supported on the other end of the lever 1103 via a male screw 1109. This weight 1107 reduces the weight of the movable parts such as the welding head 1 and the welding arm 3 and rotates to change the position thereof so that the heating tip 2 is heated.
It is possible to adjust the pressing force applied to the soldered parts 7, 8.

The moving means 11 is equipped with a motor 1108 whose drive is controlled by the motor control means 12.

The motor control means 12 is configured such that, when the switch 1201 is closed, a start signal is sent to the motor control section 1202, and the motor control section 1202 rotates the motor 1108 clockwise or counterclockwise. . Further, the motor control means 12 uses the linear table 1101 of the moving means 11 described above.
When the limit switch 1203 detects that the motor has reached the upper end position, the limit switch 1203 causes the motor control unit 12 to
The motor 1108 is configured to stop rotating by sending a signal to 02.

When the motor 1108 rotates in this manner, the moving means 11
, The ball screw 1109 converts the rotational movement into the linear movement, and the linear table 1101 is moved in the vertical direction. The start timing setting means 13 is fixed to the linear table 1101.

The start timing setting means 13 receives a signal from the stopper 1301 that restricts the counterclockwise rotation of the lever 1103, the limit switch 1302 that detects that the lever 1103 is separated from the stopper 1301, and the limit switch 1302. At this time, the timer 1303 sends a start signal to the heating power source 14 which constitutes the power supply means after a preset time T _{1 has} elapsed.

The heating power source 14 supplies electric power to the heating chip 2, and is configured so that a supply power value and a supply time can be set. Further, the heating power source 14 is connected to the power control means 15.

The power control means 15 compares the data from the insulation resistance measuring device 16 constituting the continuity detecting means with a value preset by the setting device 1502, and when both are equal, as a result, the heating power supply 14 To reduce the amount of electric power supplied to the heating chip 2.

The insulation resistance measuring device 16 constituting this continuity detecting means is connected to the end of the covered thin wire 7 and the pattern 801 of the circuit board 8 and when a signal is sent from the timer 1303, insulation between the two is provided. The resistance is measured. The coated thin wire 7 and the pin 701 holding the coated thin wire 7 are covered with the coated thin wire 7.
The coating is peeled off to make it conductive.

Next, the operation will be described with reference to FIGS. 2 and 3.

FIG. 2 is a timing diagram of the moving position of the heating tip, the amount of electric power supplied from the heating power source 14 to the heating tip, and the measurement of the insulation resistance measuring instrument. FIG. 3 shows the vicinity of the soldered portion,
(A) shows the state immediately before the power supply to the heating chip,
(B) shows a state in which the coating of the coated thin wire is melted.

First, when the switch 1201 is closed and a start signal is input to the motor control unit 1202, the motor control unit 1202 drives the motor 1108 in the direction of moving the linear table 1101 downward. When the linear table 1101 moves downward, the welding head 1 descends and the heating tip 2 moves to the soldered portion 7,
Touch 8. When the welding head 1 continues to descend further,
As shown in FIGS. 3A and 2A, the heating chip 2 presses the soldered portions 7, 8 with a predetermined force, and the lever 1103 separates from the stopper 1301. When the limit switch 1302 detects that the lever 1103 is separated from the stopper 1301, the limit switch 1302 is turned on and a signal is sent to the timer 1303. When the timer 1303 reaches the position b shown in FIG. 2 after the preset time T ₁ has passed, it sends a signal to the heating power source 14 to supply a large amount of power from the heating power source 14 to the heating chip 2 for a predetermined time T. ₃ supply. On the other hand, the insulation resistor 16 sets the initial state by the signal from the timer 1303.

In this way, when power is supplied to the heating tip 2 and the position reaches the position C shown in FIG. 2, the coating of the coated thin wire 7 begins to melt.

Then, at the position d shown in FIG. 2, that is, after the power is supplied to the heating tip 2, T ₂ time elapses, and the coated fine wire 7
When the insulation resistance measuring instrument 16 measures the value
When it becomes equal to the set value of 1502, the power supplied from the heating power source 14 to the heating chip 2 is reduced by the signal from the comparison circuit 1501.

Then, when the supply time of the electric power from the heating power source 14 to the heating tip 2 elapses T ₃ , the motor 1108 rotates counterclockwise and the linear table 1101 moves upward, so that the heating tip 2 rises and the heating power source increases. The power supply from 14 to the heating chip 2 is stopped.

Then, when the linear table 1101 reaches the upper end position and the limit switch 1203 detects this, the motor control unit 1202 stops the rotation of the motor 1108 by the signal from the limit switch 1203, and the soldering work is completed.

Therefore, according to the present embodiment, the amount of power supplied to the heating chip 2 is controlled according to the change in the insulation resistance value between the coated thin wire 7 and the pattern 801 of the circuit board 8, so that excessive heating is prevented. In addition, the cooling rate can be improved, whereby oxidation can be reduced to obtain a solder having a fine structure and the tact can be shortened.

In addition, in this embodiment, the insulation resistance measuring device 16 uses the covered thin wire 7
, And the pattern 801 of the circuit board 8 has been described, but the invention is not limited to this, and the change in the insulation resistance between the heating chip 2 and the covered thin wire 7 is measured, for example. It is also possible.

Further, instead of detecting the change in the insulation resistance between the covered thin wire 7 and the pattern 801 of the circuit board 8, it is also possible to simply detect the presence or absence of conduction between the two. In this case, insulation resistance measuring instrument 16, comparator circuit 1501 and setting instrument 15
Use a continuity tester or the like instead of 02.

Further, although the case where tungsten is used as the material of the heating tip 2 is shown, the material is not limited to this, and other materials such as molybdenum, tantalum, and stainless can be used.

〔The invention's effect〕

Since the present invention is configured as described above,
You can prevent excessive heating and increase the cooling rate,
As a result, the oxidation of the solder is minimized, a solder having a fine metal structure is obtained, and the alloy layer formed between the soldered component and the solder has an appropriate thickness. Further, it is not necessary to provide the cooling time in a form that affects the tact time, and the time can be shortened.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main configuration of a reflow soldering apparatus according to an embodiment of the present invention, and FIG. 2 is a moving position of a heating chip and an amount of power supply from a heating power source to the heating chip and insulation. FIG. 3 shows a timing diagram with the measurement of the resistor, FIG. 3 shows the vicinity of the soldered portion, (a) shows the state immediately before the power supply to the heating chip, and (b) shows the coating of the coating thin wire. The molten state is shown. 1 ... welding head, 2 ... heating tip, 3 ... welding arm,
7 ... Coated fine wire, 8 ... Circuit board, 11 ... Movement means, 12
...... Motor control means, 13 …… Start timing setting means, 14 …… Heating power supply, 15 …… Power control means, 16 …… Insulation resistance measuring instrument.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akimichi Yamamoto 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Hitachi, Ltd. Institute of Industrial Science (72) Inventor Yukinobu Hirai 2880, Kozu, Odawara-shi, Kanagawa Stock Company Hitachi Odawara Factory

Claims (1)

[Claims] 1. A heating chip for melting solder in a portion to be soldered, an electric power supply means for supplying electric power to the heating chip to generate heat, and a heating chip contacting and pressing the portion to be soldered and separated from each other. A moving means, a heating chip and a coating thin wire, or a conduction detecting means for detecting conduction of any one of the coated thin wire and the circuit pattern, and the heating chip,
After pressing the soldered part, start timing setting means for starting the supply of power from the power supply means to the heating chip at a predetermined timing, and either the heating chip and the coated thin wire or the coated thin wire and the circuit pattern are conducted. At this time, a reflow type soldering device provided with a power amount control means for controlling the power amount supplied from the power supply means to the heating chip.