JPH0679767B2 - Soldering equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a soldering apparatus for a printed circuit board or the like, and particularly to a wave type for moving an object to be soldered such as a printed circuit board while contacting with a jet of molten solder. Related to the soldering device.

[Conventional technology]

A so-called wave type soldering device is widely used for soldering an electronic part mounted on a through hole of a printed circuit board, in which the printed circuit board is moved while a jet of molten solder (wave) is in contact with the back surface of the printed circuit board. .

In this type of soldering apparatus, for example, as shown in JP-A-49-98422, a printed circuit board (object to be soldered) is held by a holder, and after applying flux and preheating with a preheater, The printed circuit board is moved while being in contact with the solder wave, so that the connection portion of the printed circuit board is soldered. In this case, the speed at which the printed circuit board moves on the solder bath while contacting the solder wave is kept substantially constant from the time when the front end of the printed circuit board contacts the solder wave until the last end is separated from the solder bath. Was common. That is, conventionally, the contact period between the printed circuit board and the solder wave is substantially constant from the front end to the rear end of the printed circuit board.

[Problems to be Solved by the Invention]

When the front end of the printed circuit board comes into contact with the solder wave, the substrate temperature is still low, so the heat from the solder spreads from the front end to other parts, and the temperature of the front end does not rise easily. On the other hand, at the rear end of the printed circuit board, the temperature due to heat conduction inside the board has already risen before contacting the solder wave, so even if contact is made for the same time as the solder wave, the temperature is higher than that at the front end. Will be heated.

In this way, when the printed board is moved at a constant speed on the solder bath, the heating temperature of the printed board becomes non-uniform.
This heating temperature difference within the printed circuit board is acceptable for small and low-density printed circuit boards, but for large-sized and high-density printed circuit boards, the heating temperature difference within the board increases, resulting in poor bonding quality and mounting electronic component characteristics. The impact on it cannot be ignored. In other words, as the printed circuit board becomes larger and more dense, the board thickness and heat capacity will increase. Therefore, when soldering, the tip of the printed circuit board, which is the most resistant to temperature rise, is heated to the required temperature. The board movement speed must be slowed considerably, but this causes the temperature at the rear end of the printed board to rise significantly, causing an unacceptable increase in the heating temperature difference within the board, resulting in unreliable joints and mounting components. Will cause deterioration of characteristics.

As a countermeasure against this, for example, as described in JP-A-52-36540, the speed may be changed from low speed to high speed as the printed circuit board moves. However, conventionally, by using a motor that is previously controlled so as to continuously increase the rotation speed with the passage of time as a motor for controlling the movement of the printed circuit board, the movement speed of the printed circuit board is similarly reduced with the passage of time. The speed of the printed circuit board is not fed back to the motor speed control because the actual relative position of the printed circuit board to the solder wave or the actual temperature difference between the front side and the rear side of the printed circuit board is not fed back to the motor speed control. There was an excess or deficiency in the moving speed, and there was a limit to making the heating temperature of the printed circuit board uniform.

The object of the present invention is to solve the above-mentioned problems of the prior art, to the actual relative position with respect to the solder wave of the object to be soldered such as a printed circuit board and the actual temperature difference between the front and the rear on the object to be soldered. Based on this, the moving speed of the object to be soldered is appropriately controlled to further improve the uniformity of the heating temperature of the object to be soldered.

[Means for Solving the Problems]

In order to achieve the above object, the soldering apparatus of the present invention is a means for moving an object to be soldered along a certain path, and a molten solder for contacting the object to be soldered in the middle of the path. A means for generating a jet, a means for sequentially detecting the relative position of the soldered object to the molten solder jet at predetermined intervals in accordance with the movement of the soldered object, and each time the relative position is detected, And means for stepwise controlling the moving speed of the means for moving the object to be soldered from low speed to high speed.

Further, the soldering apparatus of the present invention, means for moving the object to be soldered along a certain path, and means for generating a jet of molten solder for contacting the object to be soldered in the middle of the path , Means for detecting the temperature of a portion of the soldered object that is in contact with the molten solder jet and a portion of the portion that is not in contact with the molten solder jet behind the molten solder jet according to the movement of the soldered object, A temperature difference (temperature difference) and controlling the moving speed of the means for moving the object to be soldered so as to be inversely proportional to the temperature difference.

[Action]

As the object to be soldered moves into contact with the solder wave from its tip, the temperature of the contacted part rises, and at the same time, heat is radiated to the rear end side by heat conduction of the object to be soldered, The temperature of the part also rises. That is, the contact time with the solder wave required for heating the object to be soldered to a constant temperature becomes shorter from the front end toward the rear end. Therefore, the moving speed of the object to be soldered during the contact period with the solder wave is
By appropriately changing from low speed to high speed, the contact time with the solder wave can be appropriately reduced from the front end to the rear end of the object to be soldered, and the heating temperature of the object to be soldered can be made uniform. it can.

According to the soldering apparatus of the present invention, as the object to be soldered moves, the actual relative position of the object to be soldered to the solder wave is sequentially detected, and the moving speed of the object to be soldered is determined based on the result. Since the speed is controlled stepwise from low speed to high speed, the heating temperature of the object to be soldered can be easily equalized, and highly reliable soldering can be performed.

In addition, the temperature difference between the part to be soldered, which is in contact with the solder wave, and the non-contact part behind it, is maximum when the tip part of the object to be soldered contacts the solder wave, The temperature difference decreases as the contact part of moves to the rear end side. According to the soldering apparatus of the present invention, by detecting this temperature difference, by controlling the moving speed of the object to be soldered in inverse proportion to the temperature difference,
As the object to be soldered moves, its moving speed can be appropriately changed from low speed to high speed, and soldering with higher reliability can be performed.

〔Example〕

FIG. 1 is a schematic plan view of a soldering apparatus according to a first embodiment of the present invention, and FIG. 2 is a diagram showing a change in moving speed of a printed circuit board (object to be soldered) in the present embodiment. .

In FIG. 1, a solder bath 1 is filled with molten solder, and a screw (not shown) for generating a jet of molten solder, that is, a wave 2 is provided inside the solder bath 1. This screw is driven by the motor 3. 5 is a printed circuit board (object to be soldered)
It is a hanger that moves on the conveyor rail 4 while holding 6, and is driven by a motor 10 via a chain 9.

In order to detect the relative position of the printed circuit board 6 with respect to the solder wave 2, sensor sensing pieces 7A, 7B, 7C, 7D are provided at appropriate positions on one side of the hanger 5, and the approach thereof is sensed. A sensor 8 is provided in place. The position detection circuit 11 detects the relative positions of A, B, C and D in FIG. 2 based on the output of the sensor 8. The speed controller 12 responds to the detection output of the position detection circuit 11 and drives the motor 10 so as to drive the motor 10 so as to move the printed circuit board 6 at the speed shown in FIG.

Next, the operation will be described. Initially, the speed controller 12 drives the motor 10 so as to move the hanger 5 at the speed of A shown in FIG.

When the hanger 5 moves to a position where the sensor sensing piece 7A is sensed by the sensor 8 (position A in FIG. 2) and the position detection signal is output from the position detection circuit 11, the speed controller
12 decelerates the motor 10 so that the moving speed is as shown in FIG.

At this speed, the printed circuit board 6 starts to contact the solder wave 2 from the tip. When the hanger 5 further advances and the sensor sensing piece 7B is sensed by the sensor 8, that is, when the relative position of B in FIG. 2 is reached, the speed controller 12 drives the motor 10 so as to obtain the moving speed of C in FIG. To accelerate.

Further, proceed to the relative position of C in FIG.
When the sensing signal of is output from the sensor 8, the speed controller
12 accelerates the motor 10 again so that the speed becomes the speed shown in FIG.

After that, when the hanger 5 moves to the position where the sensor sensing piece 7D is sensed by the sensor 8, the speed controller 12 accelerates the motor 10 again, and returns the moving speed to the speed of A in FIG.

In this way, by sequentially detecting the relative position of the printed circuit board 6 and the solder wave 2 and setting the slowest speed when the tip portion of the printed circuit board 6 comes into contact with the solder wave, and thereafter increasing the moving speed stepwise. Therefore, it is possible to reliably heat the printed board 5 from its front end to its rear end to a substantially uniform temperature for soldering. Note that FIG. 2 is merely a conceptual illustration of how the speed changes.

FIG. 3 is a schematic plan view of a soldering apparatus according to a second embodiment of the present invention, and FIG. 4 is a view schematically showing a change in moving speed of a printed circuit board in the present embodiment, and FIG. FIG. 6 is a diagram showing a relationship between a temperature difference and a moving speed.

In FIG. 3, the hanger 5 is provided with two sensor sensing pieces 7E and 7F at the positions shown. Further, the temperature measuring device 13A for measuring the surface temperature (T1) of the printed circuit board 6 from above the solder wave 2 in a non-contact manner, and the surface temperature (T2) of the printed circuit board 6 from the upper side at a position behind the temperature measuring device 13A A temperature measuring device 13B for contact measurement is provided. As the temperature measuring devices 13A and 13B, for example, infrared temperature measuring devices are used. 15A and 15B are temperature measuring devices 13
A circuit that converts the detection signals of A and 13B into signals suitable for calculation,
Reference numeral 16 is a circuit for calculating a temperature difference ΔT (= T1-T2) from the converted signal, and 17 is a speed controller for performing speed control as shown in FIG. 4 according to the temperature difference and the detection signal from the sensor 8. The other points are the same as in the first embodiment.

Next, the operation will be described. The speed controller 17 drives the motor 10 so as to move the hanger 5 at the speed shown in FIG.

When the hanger 5 moves to a position where the tip of the printed circuit board 6 contacts the solder wave 2, a sensor 8 outputs a detection signal from the sensor detection piece 7E, so that the speed controller 17 switches to the variable speed mode, as shown in FIG. According to the temperature difference function f (ΔT) such as
The drive of the motor 10 is controlled so as to move at a speed of C which is approximately inversely proportional to.

When the front end of the printed circuit board 6 comes into contact with the solder wave 2, the temperature of the rear part larger than that is low and the temperature difference ΔT is large, so the moving speed is slow. Thereafter, as the contact portion moves to the rear end side, the temperature difference ΔT decreases, so that the moving speed gradually increases.

When the hanger 5 moves to a position where the sensor 8 outputs the detection signal of the sensor sensing piece 7F, the speed controller 17 returns to the constant speed mode, and the motor 10 is moved so as to move the hanger 5 at the speed shown in FIG. To drive.

With such a moving speed system, the heating temperature of the printed circuit board 6 is surely made uniform, and highly reliable soldering becomes possible.

Since the purpose of the moving speed device of the printed circuit board is to make the heating temperature of the printed circuit board uniform, the method of directly monitoring the temperature of the printed circuit board as in this embodiment achieves highly uniform heating temperature uniformity. It is possible.

In each embodiment, the mechanism for moving the printed circuit board and the like may be changed as necessary. Further, in the embodiment, the object to be soldered is the printed circuit board, but it goes without saying that it may be other than the printed circuit board.

〔The invention's effect〕

As explained above, according to the soldering apparatus of the present invention,
Along with the movement of the object to be soldered, the relative position with respect to the solder wave of the object to be soldered or the temperature difference between the front and the rear on the object to be soldered is sequentially detected, and the movement of the object to be soldered is based on that. Since the speed is gradually changed from low speed to high speed, the heating temperature of the soldered object can be reliably and easily uniformed during the contact period with the solder wave of the soldered object. It is possible to improve the reliability of soldering, etc., and it is possible to prevent deterioration of characteristics of components mounted on the printed circuit board.

[Brief description of drawings]

1 and 2 are respectively a schematic plan view of a soldering apparatus according to a first embodiment of the present invention and a view showing a moving speed of a printed circuit board, and FIGS. 3 to 5 are respectively a second view of the present invention. 3A and 3B are a schematic plan view of a soldering device according to an example, a diagram showing a moving speed of a printed circuit board, and a diagram showing a speed function. 1 ... Solder tank, 2 ... Solder wave, 3 ... Screw drive motor, 4 ... Coveyor rail, 5 ... Hanger, 6 ... Printed circuit board, 7A-7F ... Sensor sensing piece, 8 ... Sensor, 9 …… Chain, 10 …… Hanger drive motor, 11 …… Position detection position, 12,17 …… Speed controller, 13A, 13B …… Temperature measuring instrument, 15A, 15B …… Temperature detection circuit, 16 …… Temperature difference calculation circuit.

Claims (2)

[Claims] 1. A means for moving an object to be soldered along a fixed path, a means for generating a jet of molten solder for contacting the object to be soldered in the middle of the path, and the object to be soldered According to the movement of the object, means for sequentially detecting the relative position of the soldered object to the molten solder jet at predetermined intervals, and movement of the means for moving the soldered object each time the relative position is detected. And a means for controlling the speed stepwise from a low speed to a high speed. 2. A means for moving an object to be soldered along a certain path, a means for generating a jet of molten solder for contacting the object to be soldered in the middle of the path, and the object to be soldered According to the movement of the object, means for detecting the temperature of the portion to be soldered, which is in contact with the molten solder jet and the portion not in contact with the molten solder jet, and the difference between the detected temperatures. (Hereinafter referred to as temperature difference), and means for controlling the moving speed of the means for moving the object to be soldered so as to be in inverse proportion to the temperature difference.