JP6874979B2 - Laser soldering method and laser soldering equipment - Google Patents

Description

The present invention relates to a laser-type soldering method for soldering using laser light and a laser-type soldering apparatus used for carrying out the method.

Conventionally, a technique of soldering a part (soldering point) to be soldered between a printed circuit board and an electronic component by using a laser beam has been known. For example, Patent Document 1 describes a laser oscillator for outputting a laser beam, an irradiation head for irradiating a soldering point with a laser beam output from the laser oscillator, and a solder supply for supplying linear solder to the soldering point. A laser soldering apparatus having an apparatus and a controller for controlling the output of a laser oscillator is disclosed. This laser-type soldering device heats the soldering point by outputting a laser beam of intensity corresponding to the control signal from the controller from the laser oscillator, and at the same time, the linear solder supplied to the soldering point is the laser. It is melted by light and soldered.

At this time, the laser soldering apparatus is provided with a non-contact temperature sensor (radiation thermometer) that measures the temperature by infrared rays, and the radiation thermometer receives infrared rays radiated from the soldering point. Then, the temperature of the soldering point is measured in real time from the amount of infrared rays received, and based on the measured temperature, the output of the laser beam is output so that the temperature of the soldering point is always the optimum temperature (target temperature). Increase / decrease control.

By the way, when measuring the temperature of a soldering point with the radiation thermometer, the emissivity of infrared rays at the soldering point is set in advance in the controller, and the temperature is measured based on the emissivity. However, the emissivity of an object has a unique value for each material, and the emissivity differs depending on the surface condition of the object. Therefore, when the soldering point contains a plurality of metals, the emissivity of any metal should be set. It is very difficult to select the metal, and if the selection is incorrect, accurate temperature measurement cannot be performed, so that the output of the laser beam cannot be controlled accurately.

For example, when the soldering points are a terminal formed on a printed circuit board and a lead of an electronic component, both are formed of different metal materials (for example, copper, silver, gold, tin, etc.) and are mutually formed. Since the emissivity is different, it is necessary to set the emissivity of one of the metal materials, but even if one emissivity is set, the positions of the terminal and the lead are still in the plurality of soldering points. If there is any deviation, the object to be measured by the emissivity thermometer changes from the terminal to the lead or from the lead to the terminal at the soldering point, which tends to cause a measurement error. Further, when linear solder is supplied to the soldering point and the linear solder is melted by the laser beam and diffused to the soldering point, the terminal or lead is covered with the diffused solder, so that the emissivity thermometer at that point. Since the object to be measured is changed to solder and the emissivity of the solder containing tin as a main component is different from the emissivity of the terminals and leads, the measurement temperature varies.

In this way, in the past, the temperature of the soldering point was measured in real time with a radiation thermometer, and the output of the laser beam was controlled so that the measured temperature reached the target temperature. Since variations occur, it is difficult to control the output of the laser beam with high accuracy according to the target temperature, and there are many cases where solder defects occur because the soldering points are not heated to an appropriate temperature.

Japanese Unexamined Patent Publication No. 2010-26093

The present invention has been made in view of the above circumstances, and it is possible to accurately control the output of the laser beam so that the soldering point is heated to the target temperature, thereby performing high-quality soldering. The technical issue is to be able to do it.

In order to solve the above problems, the present invention includes a first step of irradiating a laser beam to preheat the soldering point, and a second step of melting the supplied solder with the laser beam and diffusing it to the soldering point. In a laser-type soldering method that includes a third step of post-heating the solder diffused to the soldering point with laser light, the entire soldering process from the beginning of the first step to the end of the third step is waveform-controlled in the first half. It is divided into a region and a temperature control region in the latter half. In the waveform control region, the laser beam output and irradiation time required to heat the soldering point to the target temperature are preset as control waveforms, and the control waveform is followed. In the temperature control range, the temperature of the soldering point is preset as the target temperature for each hour , and the target temperature and the soldering point after solder diffusion measured by the radiation thermometer are measured. The measured temperature is compared, the output of the laser beam is controlled so that the deviation between these target temperatures and the measured temperature becomes zero, and the radiation rate of the temperature measurement target by the radiation thermometer is that of tin, which is the main component of the solder. It is characterized in that it is set to the radiation rate.

Also, in the present invention, switching from the waveform control by the control waveform, to the temperature control based on the measured temperature may also be performed after the solder supply to the soldering point.

Further, in order to solve the above problems, according to the present invention, a laser oscillator that outputs a laser beam, an irradiation head that irradiates a laser beam from the laser oscillator toward a soldering point, and a temperature of the soldering point. It has a radiation thermometer that measures the laser, a solder supply device that supplies the solder to the soldering point, and a control device that controls the entire soldering device according to a control program . Set to the radiation coefficient of tin, which is the main component, the control device has a control waveform for controlling the output and irradiation time of the laser beam required to heat the soldering point to the target temperature , and the soldering point. The target temperature for each time is input, and after performing waveform control that controls the output of the laser beam along the control waveform until the solder diffuses to the soldering point, it was measured with the radiation thermometer. A laser-type soldering apparatus characterized in that the temperature is controlled to control the output of laser light so that the deviation between the measured temperature at the soldering point after solder diffusion and the target temperature becomes zero. Is provided.

In the present invention, the output and irradiation time of the laser beam are controlled by waveform control based on a preset control waveform, and after the waveform is controlled, the preset target temperature is compared with the measurement temperature at the soldering point. The temperature is controlled so that the deviation between the target temperature and the measured temperature becomes zero. Therefore, the output of the laser beam is controlled more accurately than the conventional method in which the output of the laser beam is constantly controlled based on the temperature measured by the radiation thermometer over the entire soldering process, resulting in higher quality. Can be soldered.

It is a schematic diagram which shows the 1st Embodiment of the laser type soldering apparatus which concerns on this invention. (A) is a plan view of the soldering point, and (b) is a sectional view of the same. (A) is a cross-sectional view showing the first step of soldering, (b) is a cross-sectional view showing the second step, and (c) is a cross-sectional view showing the third step. It is a diagram which shows the control waveform which controls a laser beam. It is a diagram which shows the target temperature to be compared with the measurement temperature. It is a diagram which shows the relationship between the output and irradiation time of a laser beam at the time of soldering, the temperature measured by a radiation thermometer, and the target temperature. It is a schematic diagram which shows the 2nd Embodiment of the laser type soldering apparatus which concerns on this invention.

Hereinafter, the laser soldering method and the laser soldering apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment of a soldering device 1. In this soldering device 1, a laser oscillator 2 that outputs a laser beam B and a laser beam B output from the laser oscillator 2 are printed on a printed substrate. An irradiation head 3 that irradiates the soldering point P on the 20 in a condensed state, a laser controller 4 for controlling the laser oscillator 2, and a solder supply for supplying the linear solder 15 to the soldering point P. According to the device 5, the radiation thermometer 6 that receives infrared rays (radiated infrared rays) radiated from the soldering point P and measures the temperature of the point P in a non-contact manner, and the entire soldering device 1 according to a set program. It has a control device 7 that automatically controls.

As shown in FIGS. 2A and 2B, the soldering point P is an annular terminal 21 formed on the printed circuit board 20 and a lead 22 extending from the electronic component 23, and the lead 22 is a lead 22 extending from the electronic component 23. , It is inserted into the terminal 21 from the bottom upward.

The irradiation head 3 has a substantially cylindrical outer shape, and a first optical fiber 8 communicating with the laser oscillator 2 is connected to a side surface thereof, and a laser beam B output from the laser oscillator 2 transmits the optical fiber 8. It is configured to pass through and be guided to the inside of the irradiation head 3. Then, inside the irradiation head 3, optical components (illustrated) such as a semitransparent mirror that changes the direction of the introduced laser light B and an optical lens that condenses the laser light B to a predetermined diameter at a soldering point P. Omitted) is built-in. Further, an irradiation port 3a is provided at the tip of the irradiation head 3 facing the soldering point P, and the laser beam B passing through the optical component is directed from the irradiation port 3a toward the soldering point P. It is designed to be irradiated.

Further, a second optical fiber 12 leading to the radiation thermometer 6 is connected to a position on the side surface of the irradiation head 3 different from the portion to which the first optical fiber 8 is connected, from the soldering point P. The radiated infrared rays are received by the radiation thermometer 6 through the second optical fiber 12. That is, the radiated infrared rays from the soldering point reach the inside of the irradiation head 3 through the irradiation unit 3a of the irradiation head 3, pass through the optical component through which the laser beam B passes, and the base end of the irradiation head 3. After advancing to the side, it is guided into the second optical fiber 12 through an optical unit 13 composed of a lens, a semitransparent mirror, or the like, and is transmitted to the radiation thermometer 6 via the optical fiber 12.

Then, in the radiation thermometer 6, the temperature H1 of the soldering point P is obtained based on the amount of energy of the received radiated infrared rays, and the measurement temperature signal (temperature data) proportional to the obtained measurement temperature H1 is the laser controller 4. It is sent to the control device 7 via. The temperature data obtained by the radiation thermometer 6 may be sent to the control device 7 as it is without passing through the laser controller 4.

Further, a CCD camera 10 is attached to the base end portion of the irradiation head 3 so that the laser beam B and the optical axis L are aligned with each other, and the CCD camera 10 can image the soldering point P through the irradiation port 3a. It has become like. The image of the soldering point P captured by the CCD camera 10 is displayed on the monitor 11 via the control device 7, and before soldering, the image displayed on the monitor 11 is viewed with respect to the soldering point P. It can be used to adjust the aim of the laser beam B, and the state of the soldering point P can be observed during the soldering operation.

The solder supply device 5 is for feeding, for example, the required amount of the linear solder 15 wound around the pulley toward the soldering point P. The solder supply device 5 has a solder guide 16 arranged near the soldering point P, and receives a control command such as a supply timing and a supply amount of the solder 15 from the control device 7 during the soldering operation. Solder 15 is supplied from the solder guide 16 to the soldering point P according to the control command. Then, the laser oscillator 2 that receives the oscillation control command from the laser controller 4 outputs the laser light B at a predetermined output and irradiation time, and supplies the solder 15 to the laser light B, so that the solder 15 is generated by the laser light B. It is configured to be heated and melted for soldering.

Next, a method of soldering the soldering point P using the soldering device 1 having the above configuration will be described.

As shown in FIG. 3A, the soldering steps carried out in the present invention include the first step S1 in which the soldering point P is irradiated with laser light B to preheat the soldering point P, and FIG. As shown in (b), the linear solder 15 is supplied from the solder supply device 5 to the soldering point P, and the linear solder 15 is heated and melted by the laser beam B and diffused to the soldering point P ( The second step S2 to be wetted) and the solder 15 diffused to the soldering point P are post-heated by the laser beam B as shown in FIG. 3C so that the metal processed product required for soldering is produced. It is divided into three steps, the third step S3 to finish the soldering. Further, as shown in FIG. 6, the entire area of the soldering step from the beginning of the first step S1 to the end of the third step S3 is divided into a waveform control range in the first half and a temperature control range in the second half.

Prior to soldering in the first to third steps, as a preliminary step, a control waveform C (second) for controlling the output (W) and irradiation time (seconds) of the laser beam B with respect to the control device 7 ( (See FIG. 4), the measurement target whose temperature is measured by the radiation thermometer 6, and the emissivity according to the material of the measurement target are set. In the present embodiment, since the temperature measurement target by the radiation thermometer 6 is set to the solder 15, the emissivity is set to the emissivity of tin, which is the main component of the solder 15. Further, the control device 7 is set with the target temperature (measurement target temperature) H2 (see FIG. 5) at the soldering point P, and the measurement temperature H1 by the radiation thermometer 6 approaches the measurement target temperature H2. A control program for temperature control that controls the output of the laser beam is set. Then, in the waveform control range in the first half of the soldering process, the output and irradiation time of the laser beam B are controlled according to the control waveform C set in the previous step, and in the temperature control range in the latter half, the radiation thermometer 6 The measurement temperature H1 set in is compared with the predetermined measurement target temperature H2, and the laser beam B is set so that the deviation (that is, the temperature difference) between the measurement target temperature H2 and the measurement temperature H1 becomes zero. Output is controlled.

In this way, the reason why the waveform is controlled without temperature control in the first half of the soldering process is that the emissivity of the temperature measurement target by the radiation thermometer 6 is set to tin, which is the main component of the solder. Therefore, even if the temperature of the soldering point is measured when the solder is not yet supplied in the first half of the process, the measured temperature is not always accurate.

The control waveform C includes the heating target temperature of the soldering point P and the output and irradiation time of the laser beam B required to heat the soldering point P to the heating target temperature for each of the first to third steps. It is decided by asking for.

The heating target temperature is a preferable heating target temperature based on numerical simulations performed in advance, past empirical rules, etc., depending on the material, shape, size, surface condition, etc. of the terminals 21 and leads 22 forming the soldering point P. Is required in advance. For example, when the soldering point P is composed of the normal terminals 21 and the leads 22 as in the present embodiment, the preferable heating target temperature in the first step S1 before the solder 15 is supplied is 150-250 ° C. In the second step S2 of melting and diffusing the supplied solder 15, the soldering point P including the solder 15 needs to be kept at 200-300 ° C. Therefore, the preferable heating target temperature is 200-300 ° C. Further, in the third step S3 in which the soldering point P is post-heated, it is necessary to keep the soldering point P at 250-300 ° C. so that the metal compound necessary for soldering is generated, which is a preferable heating target. The temperature is 250-300 ° C.

Then, for each of the first to third steps, the output and irradiation time of the laser beam B required to heat the soldering point P to the heating target temperature are obtained by experiments, calculations, etc., and are shown in FIG. As described above, the control waveform C for controlling the output of the laser beam B and the irradiation time is determined throughout the first to third steps, and this control waveform C is input to the control device 7.

Further, as shown in FIG. 5, the measurement target temperature H2 to be compared with the measurement temperature H1 of the soldering point P in the latter half temperature control range is set for the second step S2 and the third step S3 , and the second step. The temperature is set to 300 ° C. from the beginning to the end of the step S2, 250 ° C. from the beginning to the end of the third step S3, and is set to be lowered to 0 ° C. at the end of the third step S3. In the illustrated example, the target temperature H2 in the first step S1 is omitted because the output control of the laser beam B by the temperature control is not performed during the first step S1.

Then, as described above, the setting of the control program for waveform control and temperature control for the control device 7 is completed, and the irradiation position of the laser beam B with respect to the soldering point P and the plurality of soldering points are completed by teaching. After the order of soldering P is determined, by pressing the start button, laser light B is irradiated from the laser oscillator to each of the plurality of soldering points P, and soldering is performed. Further, at the same time as the start of soldering, the temperature measurement of the soldering point P by the radiation thermometer 6 is also started.

FIG. 6 shows a control example of the laser beam B output by the waveform control in the first half and the temperature control in the second half, and shows the output and irradiation time of the laser beam B, the temperature H1 measured by the radiation thermometer 6, and the temperature H1 measured by the radiation thermometer 6. The relationship with the target temperature H2 is shown. As shown in the figure, switching from waveform control by the control waveform C to temperature control by the measurement temperature H1 is performed in the second step S2. Specifically, the area from the beginning of the first process S1 to the middle of the second process S2 is divided as a waveform control area, and the area from the middle of the second process S2 to the end of the third process S3 is divided as a temperature control area.

In the control example of FIG. 6, when the laser beam B having an output of 20 W is irradiated along the control waveform C shown by the broken line in the first step S1 (FIG. 3 (a)), the soldering including the terminals 21 and the leads 22 is performed. The measurement temperature H1 at the point P gradually rises, and immediately before the end of the first step S1, rises to about 220 ° C., which exceeds the target temperature of 150-200 ° C.

Immediately after shifting to the second step S2 (FIG. 3B), the waveform control range is still in effect. Therefore, the output of the laser beam B rises to 35 W based on the control waveform C, and the laser beam B is irradiated with this output. Will be done. Further, substantially at the same time as the start of the second step S2, a fixed amount of the linear solder 15 is supplied to the soldering point P, and the supplied solder 15 is melted by the laser beam B and diffused over the entire soldering point P. To do. At this time, since the thermal energy of the laser beam B is consumed for melting the solder 15, the measurement temperature H1 at the soldering point P temporarily drops a little, but immediately recovers and continues to rise.

After a predetermined time has elapsed from the transition to the second step S2, the output control of the laser beam B is switched from the control waveform C to the temperature control. The switching to the temperature control is preferably performed at the timing when the solder 15 melts and diffuses over the entire soldering point P. The reason is that the emissivity, which is the reference for temperature measurement by the radiation thermometer 6, is set to the emissivity of tin, which is the main component of the solder 15, and the temperature is controlled after the solder 15 is diffused. By switching, the accuracy of the measurement temperature H1 at the soldering point P can be improved.

When the output control of the laser beam B is switched to the temperature control, the control device 7 compares the measurement temperature H1 measured by the radiation thermometer 6 with the measurement target temperature H2 input to the control device 5, and the measurement is performed. The output of the laser beam B is controlled so that the deviation between the target temperature H2 and the measurement temperature H1 becomes zero. As described above, since the measurement target temperature H2 in the second step S2 is set to 300 ° C., the output of the laser beam B is controlled so that the measurement temperature H1 becomes 300 ° C. As a result, the output of the laser beam B is kept around about 35 W (see the measured waveform in FIG. 6), and after the measurement temperature H1 rises and reaches 300 ° C., the increase and decrease are repeated until the end of the second step S2. It is maintained at around 300 ° C. The comparison itself between the measurement target temperature H2 and the measurement temperature H1 may be performed in the waveform control range up to the middle of the second step S2.

Subsequently, when the process shifts to the third step S3 (FIG. 3C), the measurement temperature H1 which was about 300 ° C. immediately before the third step S3 is changed to 250 ° C. which is the target temperature H2 of the third step S3. In order to reduce the output, the output of the laser beam B is gradually reduced, and the measurement temperature H1 is lowered accordingly. Then, when the measurement temperature H1 reaches 250 ° C., the output level of the laser beam B is kept around about 30 W, and the measurement temperature H1 is maintained at around 250 ° C. In this way, the soldering point P is irradiated with the laser beam B for 0.3 seconds to perform post-heating, during which the metal work piece required for soldering is generated.

Since the measurement target temperature H2 is set to 0 ° C. at the end of the third step S3, the output of the laser beam B becomes zero accordingly. As a result, the soldering point P is naturally cooled, the measurement temperature H1 drops sharply, and finally the temperature is settled at a constant temperature.
In the actual soldering step, when the third step S3 is completed, the irradiation of the laser beam B is stopped as described above, the temperature is measured by the radiation thermometer 6, and the measurement target temperature H2 and the measurement temperature H1 are combined. The comparison is also stopped, the irradiation head 3 moves to the next soldering point P, and the same operation is performed to solder the soldering point P, and the same operation is performed for all the soldering points P. Repeated.

As described in detail above, according to the present invention, the output and irradiation time of the laser beam B required to heat the soldering point to the measurement target temperature H2 are preset as the control waveform C, and soldering is performed. The measurement target temperature H2 at the point P is set in advance, and the output of the laser beam B is controlled along the control waveform C in the waveform control range in the first half of the soldering process, and this measurement target in the temperature control range in the second half. The temperature H2 is compared with the measurement temperature H1 at the soldering point P measured by the radiation thermometer 6, and the output of the laser beam B is output so that the deviation between the measurement target temperature H2 and the measurement temperature H1 becomes zero. It is configured to control. As a result, in the waveform control range in the first half, the output of the laser beam is controlled regardless of the temperature H1 measured by the radiation thermometer 6, and in the temperature control range in the second half, the solder 15 is diffused over the entire soldering point P. After that, since the solder 15 is the measurement target of the temperature measurement, it is not affected by the variation of the measurement temperature H1, so that the output of the laser beam is controlled with high accuracy, thereby performing high-quality soldering. Can be done.

The soldering apparatus of the present invention is not limited to the above-described embodiment, and various design changes can be made without departing from the scope of the claims.
For example, in the example shown in FIG. 1, the radiated infrared rays radiated from the soldering point P are transmitted from the inside of the irradiation head 3 to the radiation thermometer 6 via the second optical fiber 12. As in the second embodiment shown, it is also possible to directly receive the infrared rays emitted from the soldering point P by the light receiving portion 6a of the radiation thermometer 6 and measure the temperature of the soldering point P. ..
Since the configurations other than the above in the second embodiment are substantially the same as those in the first embodiment, the same reference numerals as those in the case of the first embodiment are attached to the main same components of both, and the description thereof will be described. Is omitted.

Further, the control waveform C of the laser beam B and the measurement target temperature H2 shown in the above embodiment are merely examples, and for example, the materials and shapes of the terminals 21 and leads 22 forming the soldering point P, and the solder. It is also possible to change as appropriate according to various conditions such as materials. The control waveform C shown as an example in FIG. 3 has a flat linear shape so as to output the laser beam B at a constant intensity in each of the first to third steps. For example, the laser beam B is formed. The output of the above may be an inclined linear or curved waveform that changes with time, or may be a waveform that is a combination of these straight lines and curves.
Further, the timing of switching from the waveform control to the temperature control is performed after the solder 15 has diffused to the entire soldering point P in the second step S2, but it may be before or after that, for example, the third step. It can also be performed at the time of transition to S3, and can be performed at an appropriate timing.
Further, the control waveform C shown in FIG. 3 covers the entire area of the first step S1 to the third step S3, but since it is used for waveform control in at least the first half of the soldering step, this is used. , The waveform after shifting to the temperature control range may be cut.

1 Soldering device 2 Laser oscillator 3 Irradiation head 5 Soldering supply device 6 Radiation thermometer 7 Control device 15 Solder B Laser light C Control waveform H1 Measurement temperature H2 Target temperature P Soldering point

Claims (3)

The first step of irradiating the soldering point with laser light to preheat the soldering point, the second step of melting the supplied solder with the laser beam and diffusing it to the soldering point, and the second step of diffusing the solder diffused to the soldering point with laser light. In a laser soldering method having a third step of post-heating,
The entire soldering process from the beginning of the first process to the end of the third process is divided into a waveform control range in the first half and a temperature control range in the second half.
In the waveform control range, the laser beam output and irradiation time required to heat the soldering point to the target temperature are preset as control waveforms, and the laser beam output is controlled according to this control waveform.
In the temperature control range, the temperature of the soldering point is preset as the target temperature for each hour , and this target temperature is compared with the measured temperature of the soldering point after solder diffusion measured by the radiation thermometer, and these targets are compared. The output of the laser beam is controlled so that the deviation between the temperature and the measured temperature becomes zero .
The emissivity of the temperature measurement target by the radiation thermometer is set to the emissivity of tin, which is the main component of solder.
A laser soldering method characterized by this. The laser soldering method according to claim 1 , wherein the switching from the waveform control based on the control waveform to the temperature control based on the measured temperature is performed after the solder is supplied to the soldering point. A laser oscillator that outputs laser light, an irradiation head that irradiates the laser light from the laser oscillator toward the soldering point, a radiation thermometer that measures the temperature of the soldering point, and solder to the soldering point. It has a solder supply device to supply and a control device that controls the entire soldering device according to a control program.
The emissivity of the radiation thermometer is set to the emissivity of tin, which is the main component of solder.
In the control device, a control waveform for controlling the output of the laser beam and the irradiation time required to heat the soldering point to the target temperature and the target temperature for each time of the soldering point are input. After performing waveform control that controls the output of the laser beam along the control waveform until the solder diffuses to the soldering point, the measured temperature of the soldering point after the solder diffusion measured by the radiation thermometer and the said It is configured to perform temperature control that controls the output of the laser beam so that the deviation from the target temperature becomes zero.
A laser-type soldering device that is characterized by this.

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