TWI764199B - Laser soldering device and laser soldering method - Google Patents

Abstract

A laser soldering device includes a laser source, a lens group, a temperature sensor, and a feedback controller. The laser source transmits a power adjustable laser beam according to a control signal. The temperature sensor receives the infrared rays radiated from a welding point where the laser beam irradiates, to detect the temperature of the welding point, and correspondingly outputs a sensing signal according to the detected temperature. When the detected temperature are within a first temperature interval based on a target temperature, the feedback controller executes a PID algorithm to obtain a predicted error value according to an error value between the detected temperature and the target temperature. The feedback controller controls the laser source according to the predicted error value, and adjusts the transmitted power of the laser beam accordingly, so that the detected temperature can be substantially equal to the target temperature.

Description

Laser soldering device and laser soldering method

The present invention relates to a laser soldering device and a laser soldering method, and more particularly, to a laser soldering device and a laser soldering method using a power mode and a temperature feedback mode at the same time.

The laser control of the laser soldering process is divided into power mode and temperature feedback mode. The power mode sets the laser beam output power according to the characteristics of the solder joints. However, because the energy of the laser beam continues to accumulate, it is easy to cause the soldering temperature to be too high, resulting in damage to components or PCBs. On the other hand, due to the different quality of incoming components and the degree of oxidation on the surface of the component pins or PCB pads, the absorption rate of the components to the laser beam is different, resulting in insufficient energy accumulation, resulting in a lower heating temperature of the solder joints. Causes the problem of cold soldering or unmelted tin wire.

In the heating process of the temperature feedback mode, the infrared sensor receives the infrared signal generated by the heated solder joint and feeds it back to the feedback controller. The feedback controller sets the target temperature curve to adjust the output power of the laser source, and then reaches the melting point temperature of the solder, so that the components are bonded to the PCB through the solder. The temperature feedback mode improves the quality and stability of solder processing. However, if the laser beam excites abnormal light, the temperature sensor receives abnormal signals, resulting in incorrect temperature feedback sensing signals, and soldering errors may still occur.

A laser soldering device according to an embodiment of the present invention includes: a laser source, a lens group, a temperature sensor, and a feedback controller. The laser source emits a laser beam with adjustable power according to a control signal. The lens group outputs the laser beam to a welding point. The temperature sensor receives the infrared rays radiated when the laser beam irradiates the welding point, is used for detecting the temperature of the welding point, and outputs a sensing signal correspondingly according to the detected temperature. The feedback controller receives the sensing signal, and transmits the control signal to the laser source according to the sensing signal. When the detected temperature falls within a first temperature range based on a target temperature, the feedback controller executes a proportional-integral-derivative (PID) algorithm based on an error between the detected temperature and the target temperature value to calculate a prediction error value. The feedback controller controls the laser source according to the prediction error value, and adjusts the emission power of the laser beam accordingly, so that the detected temperature can be substantially equal to the target temperature. When the detected temperature falls outside the first temperature range based on the target temperature, the feedback controller controls the laser source according to a preset power, so that the laser source emits a laser beam conforming to the preset power.

In the above-mentioned laser soldering device, the laser source includes a power meter. The power meter detects the power of the laser beam, and according to the detected power of the laser beam, correspondingly outputs a power feedback signal to the feedback controller, so that the feedback controller can pass the control signal according to the power feedback signal. , adjust the power of the laser beam emitted by the laser source.

In the above-mentioned laser soldering device, the feedback controller executes the proportional-integral-derivative algorithm to generate a proportional calculation part (P), an integral calculation part (I) and a differential calculation part (D). The proportional calculation part multiplies the error value between the currently detected temperature and the target temperature by a first gain (K _p ) to obtain a proportional result. The integral calculation part adds the error values at each past time point to obtain an error sum, and multiplies the error sum by a second gain (K _i ) to obtain an integral result. The differential calculation part performs first-order differentiation on the current error value to obtain a future error value, which is used to predict the future change of the error value, and multiplies the future error value by a third gain (K _d ) to obtain A differential result.

In the laser soldering device described above, the feedback controller adds the proportional result, the integral result and the differential result to obtain the prediction error value.

In the laser soldering device as described above, when the detected temperature falls within a first temperature range based on the target temperature and is also within a second temperature range based on the target temperature, the feedback controller increases the first gain , the second gain and the third gain are set as a first value group. The first temperature interval includes the second temperature interval.

In the laser soldering device described above, when the detected temperature falls within the first temperature range based on the target temperature, but is not within the second temperature range based on the target temperature, the feedback controller adjusts the first gain, the second temperature range, and the The second gain and the third gain are set as a second value group. The second set of values is not identical and not completely different from the first set of values.

The laser soldering method according to the embodiment of the present invention includes the following steps: transmitting a laser beam with adjustable power to a welding point according to a control signal; to detect the temperature of the solder joint; output a sensing signal correspondingly according to the detected temperature; receive the sensing signal, and obtain the detected temperature from the sensing side signal; when the detected temperature falls based on a When the target temperature is within a first temperature range, a proportional-integral-derivative (PID) algorithm is executed, and a prediction error value is calculated according to an error value between the detected temperature and the target temperature; correspondingly according to the prediction error value Adjust the emission power of the laser beam so that the detected temperature can be substantially equal to the target temperature; when the detected temperature falls outside the first temperature range based on the target temperature, adjust the laser beam according to a preset power transmit power.

In the above-mentioned laser soldering method, performing the proportional-integral-derivative algorithm includes: multiplying the error value between the currently detected temperature and the target temperature by a first gain (K _p ) to obtain a proportional result; The error values at each time point in the past are added to obtain an error sum, and the error sum is multiplied by a second gain (K _i ) to obtain an integration result; the current error value is first-order differential, and A future error value is obtained to predict the future change of the error value, and the future error value is multiplied by a third gain (K _d ) to obtain a differential result.

In the above-mentioned laser soldering method, the proportional-integral-derivative algorithm further includes: adding the proportional result, the integral result and the differential result to obtain the prediction error value.

In the laser soldering method as described above, when the detected temperature falls within the first temperature range based on the target temperature and is also within a second temperature range based on the target temperature, the first gain and the second gain are and the third gain is set as a first value group. The first temperature interval includes the second temperature interval.

In the laser soldering method as described above, when the detected temperature falls within the first temperature range based on the target temperature, but is not within the second temperature range based on the target temperature, the first gain, the second gain and the The three gains are set as a second value group. The second set of values is different from the first set of values.

The invention is described with reference to the accompanying drawings, wherein like reference numerals designate similar or identical elements throughout. The above drawings are not drawn to actual scale, but merely provide an illustration of the present invention. Some aspects of the invention are described below as references to illustrate exemplary applications. This means that many specific details, relationships and methods are set forth to provide a complete understanding of the invention. In any event, one having ordinary knowledge in the relevant art will recognize that the invention may be practiced without one or more of the specific details or otherwise. In other instances, well-known structures or operations have not been listed in detail to avoid obscuring the invention. The invention is not limited by the recited acts or order of events, as some acts may occur in a different order or concurrently with other acts or events. Furthermore, not all recited acts or events need to be performed in the same way as prior inventions.

FIG. 1 is a schematic diagram of a laser soldering device 100 and its operating environment according to an embodiment of the present invention. As shown in FIG. 1 , the laser soldering device 100 includes a laser source 102 , a lens group 104 , a temperature sensor 106 , and a feedback controller 108 . The laser source 102 emits a laser beam 118 with adjustable power according to a control signal 112 from the feedback controller 108 . In some embodiments, the laser source 102 may be a laser generator including a laser diode (not shown), or other types of laser generators. In some implementations, the laser source 102 further includes a power meter 110 . The power meter 110 can detect the power of the laser beam 118, and according to the detected power of the laser beam 118, correspondingly output a power feedback signal 114 to the feedback controller 108, so that the feedback controller 108 can detect the power of the laser beam 118 according to the power The signal 114 is fed back, and the power of the laser beam 118 emitted by the laser source 102 is adjusted through the control signal 112 .

The laser beam 118 emitted by the laser source 102 is transmitted to the lens group 104 through the optical fiber 130 . The lens group 104 outputs the laser beam 118 to a pad 124 and a component pin 122 on a circuit board 120 for soldering the component pin 122 and the pad 124 together, so that the component pin 122 can be fixed on the circuit board 120 superior. In some embodiments, the lens group 104 may be a convex lens group or a combination lens group of concave-convex lenses, for projecting the laser beam 118 onto the device pins 122 and the pads 124 . In some embodiments, the laser source 102 can be replaced by a generator of electromagnetic waves such as X-ray, ultraviolet light, megahertz wave, microwave, etc., but the invention is not limited thereto. In some embodiments, the laser beam 118 is not limited to a focused beam, but can also be a parallel beam.

When the laser beam 118 is irradiated on the pin 122 and the pad 124 of the device, due to the high energy characteristic of the laser beam 118, the temperature of the pin 122 and the pad 124 continues to rise with time. Above the melting point of the solder (eg, tin wire, not shown), the solder melts into a liquid state and penetrates into the holes between the component pins 122 and the pads 124 . After cooling down, the solder solidifies into a solid state again, so that the component pins 122 and the pads 124 can be electrically connected. In some embodiments, in the process of continuously heating up to a target temperature, the surface of the pins 122 , the pads 124 and the circuit board 120 (commonly referred to as a solder joint) will radiate infrared rays 126 , which are detected by the temperature sensor 106 . Measurement.

The temperature sensor 106 receives the infrared rays 126 radiated when the laser beam 118 is irradiated to the pins 122 and the pads 124 , and is used to detect the temperature of the pins 122 and the pads 124 according to the intensity of the received infrared rays 126 . The detected temperature correspondingly outputs a sensing signal 116 to the feedback controller 108 . Generally speaking, when the temperature of the pins 122, the pads 124 and the circuit 120 is higher, the intensity of the infrared rays 126 radiated by them is stronger, so that the intensity of the infrared rays 126 received by the temperature sensor 106 is also higher, and the temperature The temperature of the pins 122 , the pads 124 and the circuit 120 measured by the sensor 106 is also higher. Then, the temperature sensor 106 transmits the sensing signal 116 to the feedback controller 108 according to the detected temperature of the solder joint.

In some embodiments, the sensing signal 116 may carry temperature information including a plurality of bits, or referred to as temperature raw data. The temperature sensor 106 converts the temperature of the detected solder joints into temperature raw data in digital form, and carries the temperature raw data in the sensing signal 116 , and finally transmits it to the feedback controller 108 . In some embodiments, the temperature sensor 106 may be a pyroelectric infrared (PIR) sensor, a thermopile infrared sensor, or other types of infrared sensors. In some embodiments, the lens group 104 and the temperature sensor 106 are disposed in a laser soldering sub-device 128, but the invention is not limited thereto. In some embodiments, the lens group 104 and the temperature sensor 106 may be independently disposed within the laser soldering device 100 . In some embodiments, the temperature sensor 106 is not limited to a non-contact sensor, and may also be a temperature measuring instrument such as a contact sensor or an equivalent temperature sensor. In some embodiments, the target measured by the temperature sensor 106 is not limited to infrared rays, but can also be far-infrared light, color temperature, etc., and can measure the target of equivalent temperature.

The feedback controller 108 receives the sensing signal 116 from the temperature sensor 106 . In some embodiments, the feedback controller 108 extracts the temperature information of the detected solder joints from the received sensing signal 116, and compares the detected temperature with a target temperature at the current time point for the basis of An error value between the detected temperature and the target temperature is correspondingly sent to the laser source 102 by the control signal 112 .

FIG. 2 is a relationship diagram between the detected temperature of the temperature sensor 106 of the laser soldering device 100 of FIG. 1 and a target temperature according to the embodiment of the present invention. As shown in FIG. 2 , the feedback controller 108 in FIG. 1 can set different target temperatures at different time points, thereby forming the target temperature curve 200 in FIG. 2 . The feedback controller 108 reads the detected temperature information in the sensing signal 116 transmitted by the temperature sensor 106 at different time points to form the detected temperature curve 202 in FIG. 2 . In some embodiments, the production line tester sets the target temperature curve 200 through a user interface (UI) (not shown) of the laser soldering device 100 , so that the feedback controller 108 at different time points according to the detected temperature and Perform corresponding operations on the error value of the target temperature.

In some embodiments, the feedback controller 108 may set the temperature interval 204 and the temperature interval 206 which are changed based on the target temperature curve 200 according to the welding requirements and past welding experience. When the detected temperature falls within the temperature range 204 based on the target temperature curve 200 , that is, when the absolute value of the error between the detected temperature and the target temperature is less than or equal to a first threshold, the feedback controller 108 executes a proportional-integral- A differential (PID) algorithm calculates a prediction error value according to the error value between the detected temperature and the target temperature. The feedback controller 108 controls the laser source 102 through the control signal 112 according to the prediction error value, and adjusts the emission power of the laser beam 118 accordingly, so that the detected temperature can be substantially equal to or close to the target temperature. When the detected temperature falls outside the temperature range 204 based on the target temperature curve 200 , that is, when the absolute value of the error between the detected temperature and the target temperature is greater than the first threshold, the feedback controller 108 controls the The signal 112 controls the laser source 102 so that the laser source 102 emits a laser beam 118 with a predetermined power.

For example, as shown in FIG. 2 , at time point t1 , the target temperature is the temperature value at point E on the target temperature curve 200 , and the detection temperature is the temperature value at point A on the detection temperature curve 202 . Since the detected temperature falls outside the temperature range 204 at the time point t1, in other words, the absolute value of the error between the detected temperature and the target temperature is greater than the first threshold, so the return of the laser soldering device 100 in FIG. The controller 108 controls the laser source 102 through the control signal 112 according to the preset power, so that the laser source 102 emits the laser beam 118 with the preset power. In some embodiments, the preset powers at different time points may be different values, or may be the same value. In some embodiments, the preset power is a set value obtained from past welding experience. By adjusting the transmission power of the laser beam 118 to the preset power, the difference between the detected temperature of the temperature sensor 106 and the target temperature can be achieved. The error value between the two can converge quickly.

At time point t2 , the target temperature is the temperature value at point F on the target temperature curve 200 , and the detected temperature is the temperature value at point B on the detected temperature curve 202 . Since the detected temperature falls within the temperature range 204 at time point t2, in other words, the absolute value of the error between the detected temperature and the target temperature is less than or equal to the first threshold, the feedback controller 108 executes the proportional-integral- The differential (PID) algorithm calculates the prediction error value based on the error value between the detected temperature and the target temperature. The feedback controller 108 then indirectly adjusts the emission power of the laser beam 118 according to the prediction error value, so that the detected temperature of the welding point detected by the temperature sensor 106 can approach the target temperature.

Similarly, at time point t3 , the target temperature is the temperature value at point G on the target temperature curve 200 , and the detected temperature is the temperature value at point C on the detection temperature curve 202 . Since the detected temperature falls within the temperature range 204 at the time point t3, in other words, the absolute value of the error between the detected temperature and the target temperature is less than or equal to the first threshold, the feedback controller 108 also performs proportional-integral - Differential algorithm, which calculates the prediction error value according to the error value between the detected temperature and the target temperature. Then, the feedback controller 108 indirectly adjusts the emission power of the laser beam 118 according to the prediction error value, so that the detected temperature of the welding point detected by the temperature sensor 106 can approach the target temperature.

In some embodiments, the feedback controller 108 executes a proportional-integral-derivative (PID) algorithm to generate a proportional computing part (P), an integral computing part (I) and a differential computing part (D). The proportional operation unit (P) has a proportional gain (K _p ). The integral operation part (I) has an integral gain (K _i ). The differential operation part (D) has a differential gain (K _d ). The proportional gain (K _p ), the integral gain (K _i ) and the differential gain (K _d ) are used to adjust the proportional calculation part (P), the integral calculation part (I) and the differential calculation part (D) in the whole proportional-integral- The respective gain values occupied in the differential (PID) algorithm. The feedback controller 108 can correspondingly set the proportional gain (K _p ), the integral gain (K _i ) and the differential gain (K _d ) according to the error value between the detected temperature and the target temperature, so that the detected temperature can be substantially equal or close to the target temperature.

For example, at the time point t2, the detected temperature (point B of the detected temperature curve 202) not only falls within the temperature range 204, but also falls within the temperature range 206. In other words, the detected temperature and the target The absolute value of the error value between the temperatures is less than or equal to a second threshold, wherein the second threshold is less than the first threshold. At this time, the feedback controller 108 sets the proportional gain (K _p ) in the proportional-integral-derivative (PID) algorithm to P2, the integral gain (K _i ) to I2, and the differential gain (K _d ) Set to D2 to obtain a gain setting group (P2, I2, D2).

At time t3, the detected temperature (point C of the detected temperature curve 202) falls within the temperature range 204, but falls outside the temperature range 206. In other words, the difference between the detected temperature and the target temperature is the difference between the detected temperature and the target temperature. The absolute value is greater than the second threshold, but less than or equal to the first threshold. At this time, the feedback controller 108 sets the proportional gain (K _p ) in the proportional-integral-derivative (PID) algorithm to P1, the integral gain (K _i ) to I1, and the differential gain (K _d ) Set to D1 to obtain a gain setting group (P1, I1, D1).

FIG. 3 is a schematic diagram of the operation of the feedback controller 108 of the laser soldering device 100 of FIG. 1 according to an embodiment of the present invention. As shown in FIG. 3 , the feedback controller 108 includes a multiplexer 302 , a proportional-integral-derivative (PID) arithmetic module 304 , and a subtractor 316 . The proportional-integral-derivative algorithm module 304 is generated by the feedback controller 108 executing a proportional-integral-derivative algorithm. The proportional-integral-derivative computing module 304 includes a proportional computing unit 306 , an integral computing unit 308 , a differential computing unit 310 , a subtractor 312 , and an adder 314 . In some embodiments, the processing unit 300 of the feedback controller 108 receives the sensing signal 116 from the temperature sensor 106 and retrieves the information of the detected temperature 318 carried by the sensing signal 116 . Next, the processing unit 300 transmits the detected temperature 318 to the subtractor 312 in the proportional-integral-derivative computing module 304 . The subtractor 312 subtracts the target temperature 330 and the detected temperature 318 to obtain an error value between the target temperature 330 and the detected temperature 318 .

The proportional calculation unit 306 multiplies the error value between the current detected temperature 318 and the target temperature 330 by the proportional gain (K _p ) to obtain a proportional result 322 . In some embodiments, a larger proportional gain (K _p ) results in a larger proportional result 322 for the same error value. However, if the proportional gain (K _p ) is too large, the output of the proportional-integral-derivative operation module 304 will be unstable. Conversely, if the proportional gain (K _p ) is too small, under the same error value, a smaller proportional result 322 will be obtained, so that the proportional-integral-derivative calculation module 304 can determine the detection temperature 318 and the target temperature 330 The error value is less sensitive. Therefore, when there is disturbance, the proportional-integral-derivative calculation module 304 cannot correct the disturbance.

The integral calculation part 308 adds the error values of the detected temperature 318 and the target temperature 330 at each past time point to obtain an error sum, and multiplies the error sum by the integral gain (K _i ) to obtain an integral result 324 . In some embodiments, the integral calculation unit 308 can speed up the process of the detection temperature 318 approaching the target temperature 330 . The larger the integral gain (K _i ) is, the faster the detected temperature 318 approaches the target temperature 330 .

The differential calculation unit 310 performs a first-order differential on the error value between the current detected temperature 318 and the target temperature 330 to obtain an instantaneous error variation, and then obtains a future error value, which is used to predict the error value in the future. The future error value is multiplied by the differential gain (K _d ), resulting in a differential result 326 . In some embodiments, the differential calculation unit 310 can increase the time for maintaining the error value between the detected temperature 318 and the target temperature 330 within a specific temperature range (eg, the temperature range 206 in FIG. 2 ). Finally, the adder 314 of the proportional-integral-derivative calculation module 304 adds the proportional result 322 , the integral result 324 , and the differential result 326 to obtain a prediction error value 332 . In short, the proportional-integral-derivative calculation module 304 is used to accelerate the minimization of the absolute value of the error value between the detected temperature 318 and the target temperature 330 , so that the detected temperature 318 can quickly approach or be substantially equal to the target temperature. 330.

Referring to FIGS. 2 and 3 at the same time, when the detected temperature 318 falls within the temperature range 204 in That is, the absolute value of the error value between the detected temperature 318 and the target temperature 330 is less than or equal to the first threshold, then the processing unit 300 outputs the control signal 328 to the multiplexer 302, so that the multiplexer 302 receives the data from the proportional-integral-derivative calculation module Prediction error value 332 output by 304 . The processing unit 300 receives the prediction error value 322 through the multiplexer 302, and correspondingly controls the laser source 102 through the control signal 112 according to the magnitude of the prediction error value 332, so that the laser source 102 adjusts the emission power of the laser beam 118, and This enables the detected temperature 318 of the temperature sensor 106 to be substantially equal to or close to the target temperature 330 .

In some embodiments, when the detected temperature 318 falls within the temperature range 204 in FIG. 2 and also falls within the temperature range 206 (eg, point B on the detected temperature curve 202 in FIG. 2 ), the detection When the absolute value of the error value between the measured temperature 318 and the target temperature 330 is less than or equal to the second threshold, the processing unit 300 sets the proportional gain (K _p ) of the proportional calculation unit 306 to P2 through a setting signal 320 , and the integral of the integral calculation unit 308 The gain (K _i ) is set to I2, and the differential gain (K _d ) of the differential calculation unit 310 is set to D2, so that the detected temperature 318 and the target temperature 330 can be maintained within a specific temperature range (such as the temperature range shown in FIG. 2 ). 206).

In some embodiments, when the detected temperature 318 falls within the temperature range 204 in FIG. 2, but falls outside the temperature range 206 (eg, point C on the detected temperature curve 202 in FIG. 2), the detection The absolute value of the error value between the measured temperature 318 and the target temperature ₃₃₀ is less than or equal to the first threshold, but greater than the second threshold. The integral gain (K _i ) of the calculation part 308 is set to I1, and the differential gain (K _d ) of the differential calculation part 310 is set to D1, so that the detected temperature 318 can be accelerated to approach the target temperature 330 .

In some implementations, the subtractor 316 in the feedback controller 108 subtracts the preset power 340 from the measured power carried in the power feedback signal 114 to obtain a power error 334 . Referring to FIG. 2 and FIG. 3 at the same time, when the detected temperature 318 falls outside the temperature range 204 in FIG. 2 (for example, the temperature corresponding to point A on the detected temperature curve 202 in FIG. When the absolute value of the error value between the temperature 318 and the target temperature 330 is greater than the first threshold, the processing unit 300 outputs the control signal 328 to the multiplexer 302 so that the multiplexer 302 receives the power error 334 from the adder 316 . The processing unit 300 receives the power error 334 through the multiplexer 302, and outputs the control signal 112 to the laser source 102 correspondingly according to the magnitude of the power error 334, so that the laser source 102 adjusts the transmission power of the laser beam 118, so that the power meter The power of the laser beam 118 detected by 110 can be close to or substantially equal to the preset power 340 , so as to reduce the error value between the detected temperature 318 and the target temperature 330 .

In some embodiments, when the detected temperature 318 falls outside the temperature range 204 in FIG. 2 (eg, the temperature corresponding to point A on the detected temperature curve 202 in FIG. 2 ), the detected temperature 318 and the target When the absolute value of the error value of the temperature 330 is greater than the first threshold, the preset power 340 does not pass through the subtractor 316 and is directly received by the multiplexer 302 (not shown in FIG. 3 ). In other words, the processing unit can directly and indirectly adjust the emission power of the laser beam 118 according to the preset power 340 , and can also make the detected temperature 318 substantially equal to or close to the target temperature 330 .

In some embodiments, the method in which the processing unit 300 indirectly adjusts the transmit power of the laser beam 118 according to the power error 334 (referred to as a power mode) is comparable to the method in which the processing unit 300 indirectly adjusts the transmit power of the laser beam 118 according to the prediction error value 332 This method (called a temperature feedback mode) brings the detected temperature 318 closer to or substantially equal to the target temperature 330 more quickly. Therefore, when the absolute value of the error value between the detected temperature 318 and the target temperature 330 is greater than the first threshold (eg, point A on the detected temperature curve 202 in FIG. 2 ), the control unit 300 of the feedback controller 108 of the present invention , to perform power mode. On the other hand, the control unit 300 of the feedback controller 108 of the present invention will ensure that the absolute value of the error between the detected temperature 318 and the target temperature 330 is less than or equal to the first threshold (eg, point B on the detected temperature curve 202 in FIG. 2 ). and point C), the temperature feedback mode is executed.

The invention also discloses a laser soldering method. FIG. 4 is a flowchart of a laser soldering method according to an embodiment of the present invention. As shown in FIG. 4 , the laser soldering method of the present invention includes: according to a control signal, transmitting a laser beam with adjustable power to a welding point (step S400 ); The infrared ray output is used to detect the temperature of the solder joint (step S402); a sensing signal is correspondingly output according to the detected temperature (step S404); the sensing signal is received, and the detected signal is obtained from the sensing side signal temperature (step S406); when the detected temperature falls within a first temperature range based on a target temperature, a proportional-integral-derivative (PID) algorithm is executed, according to the detected temperature and the target temperature Calculate a prediction error value according to an error value of When the measured temperature falls outside the first temperature range based on the target temperature, the emission power of the laser beam is adjusted according to a preset power (step S412 ).

In some embodiments, the laser source 102 of FIGS. 1 and 3 performs step S400. The temperature sensor 106 of FIGS. 1 and 3 executes steps S402 and S404. The control unit 300 of the feedback controller 108 of FIG. 1 and the feedback controller 108 of FIG. 3 executes step S406 , step S408 , step S410 , and step S412 . The technical features of the laser soldering method of the present invention are the same as the technical features of the laser soldering apparatus 100 in FIG. 1 , and thus will not be repeated. The laser soldering device and the laser soldering method of the present invention generally use a temperature feedback mode to heat the solder joints, and the temperature of the solder joints is monitored by a temperature sensor. When the temperature of the solder joint changes abnormally, that is, the target temperature cannot be reached or the temperature rises rapidly, the laser soldering device and the laser soldering method of the present invention can automatically switch to the power mode to heat the solder joint.

Although embodiments of the present invention have been described above, it should be understood that the above are presented by way of example only, and not limitation. Many changes to the above-described exemplary embodiments in accordance with this embodiment can be implemented without departing from the spirit and scope of the invention. Accordingly, the breadth and scope of the present invention should not be limited by the above-described embodiments. Rather, the scope of the invention should be defined by the following claims and their equivalents.

While the above-described invention has been illustrated and depicted by one or more relevant implementations, equivalent changes and modifications will occur to others skilled in the art in light of the above-described specification and drawings. Furthermore, although a particular feature of the invention has been demonstrated by one of the various implementations in question, the above-described feature may be combined with one or more other features as may be required and useful for any known or particular application .

The technical terms used in this specification are for the purpose of describing particular embodiments only, and are not intended to be used as limitations of the present invention. Unless the context clearly dictates otherwise, as used herein in the singular, the meanings of a, the and the above also include the plural. Furthermore, the words "include", "include", "(have, provided) have", "have", or variations thereof are used either as a detailed description or as the scope of the patent application. The above words mean inclusive, and to some extent, are equivalent to the word "includes."

Unless otherwise defined, all terms (including technical or scientific terms) used herein are generally understood by those of ordinary skill in the art pertaining to the above invention. We should be more aware that the above terms, such as those defined in commonly used dictionaries, should be interpreted as the same in the context of the related art. Unless expressly defined herein, the above terms are not to be construed in an idealized or overly formal sense.

100: Laser soldering device 102: Laser source 104: Lens group 106: Temperature sensor 108: Feedback controller 110: Power meter 112: Control signal 114: Power feedback signal 116: Sensing signal 118: Laser Beam 120: Circuit board 122: Component pins 124: Pad 126: Infrared 128: Laser soldering sub-assembly 130: Optical fiber 200: Target temperature curve 202: Detected temperature curve t1, t2, t3: Time points A, B, C , E, F, G: point 204, 206: temperature range 300: processing unit 302: multiplexer 304: proportional-integral-differential calculation module 306: proportional calculation section 308: integral calculation section 310: differential calculation section K _p : proportional Gain K _i : Integral gain K _d : Differential gain 312: Subtractor 314: Adder 316: Subtractor 318: Detected temperature 320: Setting signal 322: Proportional result 324: Integral result 326: Differential result 328: Control signal 330: target temperature 332: prediction error value 334: power error 340: preset power S400, S402, S404, S406: step S408, S410, S412: step

FIG. 1 is a schematic diagram of a laser soldering device and its operating environment according to an embodiment of the present invention. FIG. 2 is a relationship diagram between a temperature detected by a temperature sensor of the laser soldering device of FIG. 1 and a target temperature according to an embodiment of the present invention. FIG. 3 is a schematic diagram of the operation of the feedback controller of the laser soldering device of FIG. 1 according to an embodiment of the present invention. FIG. 4 is a flowchart of a laser soldering method according to an embodiment of the present invention.

100: Laser soldering device 102: Laser source 104: Lens group 106: Temperature sensor 108: Feedback Controller 110: Power Meter 112: Control signal 114: Power feedback signal 116: Sensing signal 118: Laser Beam 120: circuit board 122: Component pins 124: Pad 126: Infrared 128: Laser soldering sub-assembly 130: Fiber

Claims (11)

A laser soldering device, comprising: a laser source, according to a control signal, emitting a laser beam with adjustable power; a lens group, outputting the laser beam to a welding point; a temperature sensor, receiving The infrared rays radiated when the laser beam irradiates the welding point is used to detect the temperature of the welding point, and correspondingly output a sensing signal according to the detected temperature; and a feedback controller receives the temperature of the welding point. sensing a signal, and sending the control signal to the laser source according to the sensing signal; wherein when the detected temperature falls within a first temperature range based on a target temperature, the laser soldering device enters a temperature The feedback mode makes the feedback controller execute a proportional-integral-derivative (PID) algorithm to calculate a prediction error value according to an error value between the detected temperature and the target temperature; the feedback controller is based on The prediction error value controls the laser source, and adjusts the emission power of the laser beam accordingly, so that the detected temperature can be substantially equal to the target temperature; wherein the laser source includes a power meter; when the detected temperature is substantially equal to the target temperature When the temperature falls outside the first temperature range based on the target temperature, and the detected temperature is higher than the target temperature, the laser soldering device enters a power mode, so that the power meter detects the laser beam according to the correspondingly outputs a power feedback signal to the feedback controller, and the feedback controller subtracts the measured power carried by the power feedback signal from a preset power to obtain a power error; The feedback controller correspondingly outputs the control signal to the laser source according to the amount of the power error, so that the laser source emits the laser beam conforming to the preset power. The laser soldering device according to claim 1, wherein the laser source includes a power meter, the power meter detects the power of the laser beam, and outputs a corresponding power according to the detected power of the laser beam A power feedback signal is given to the feedback controller, so that the feedback controller can adjust the power of the laser beam emitted by the laser source through the control signal according to the power feedback signal. The laser soldering device as claimed in claim 1, wherein the feedback controller executes the proportional-integral-derivative algorithm to generate a proportional calculation part, an integral calculation part and a differential calculation part; the proportional calculation part calculates the current The error value between the detected temperature and the target temperature is multiplied by a first gain to obtain a proportional result; the integral calculation part adds the error value at each past time point to obtain an error sum, and Multiplying the error sum by a second gain to obtain an integration result; the differential calculation part performs first-order differentiation on the current error value to obtain a future error value, which is used to predict the future change of the error value, And the future error value is multiplied by a third gain to obtain a differential result. The laser soldering device of claim 3, wherein the feedback controller adds the proportional result, the integral result and the differential result to obtain the prediction error value. The laser soldering device of claim 3, wherein when the detected temperature falls within the first temperature range based on the target temperature and also within a second temperature range based on the target temperature, the The feedback controller sets the first gain, the second gain and the third gain as a first value group; wherein the first temperature range includes the second temperature range. The laser soldering device of claim 4, wherein when the detected temperature falls within the first temperature range based on the target temperature, but is not within the second temperature range based on the target temperature, the return The controller sets the first gain, the second gain and the third gain as a second value group; wherein the second value group is not identical and not completely different from the first value group. A laser soldering method, comprising: transmitting a laser beam with adjustable power to a welding point according to a control signal; receiving the infrared rays radiated when the laser beam irradiates the welding point to detect the welding point temperature; output a sensing signal correspondingly according to the detected temperature; receive the sensing signal, and obtain the detected temperature from the sensing side signal; when the detected temperature falls based on a target temperature When the temperature is within a first temperature range of correspondingly adjust the emission power of the laser beam according to the prediction error value, so that the detected temperature can be substantially equal to the target temperature; and when the detected temperature falls within the first temperature based on the target temperature Outside the range, and the detected temperature is higher than the target temperature, enter a power mode, which is used to output a power feedback signal correspondingly according to the detected power of the laser beam; The measured power of the carrier is subtracted from a preset power to obtain a power error; according to the amount of the power error, the emission of the laser beam is adjusted power. The laser soldering method according to claim 7, wherein executing the proportional-integral-derivative algorithm includes: multiplying the error value between the currently detected temperature and the target temperature by a first gain to obtain a Proportional result; add the error value at each time point in the past to obtain an error sum, and multiply the error sum by a second gain to obtain an integral result; and perform a first order on the current error value Differentiating to obtain a future error value for predicting the future change of the error value, and multiplying the future error value by a third gain to obtain a differential result. The laser soldering method of claim 8, wherein the proportional-integral-derivative algorithm further comprises: adding the proportional result, the integral result and the differential result to obtain the prediction error value. The laser soldering method of claim 8, wherein when the detected temperature falls within the first temperature range based on the target temperature and also within a second temperature range based on the target temperature, the The first gain, the second gain and the third gain are set as a first value group; wherein the first temperature interval includes the second temperature interval. The laser soldering method of claim 10, wherein when the detected temperature falls within the first temperature range based on the target temperature, but is not within the second temperature range based on the target temperature, the The first gain, the second gain and the first gain The three gains are set as a second value group; wherein the second value group is not identical and not completely different from the first value group.

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