CN111745249A

CN111745249A - Variable temperature controlled soldering iron

Info

Publication number: CN111745249A
Application number: CN201911173624.2A
Authority: CN
Inventors: 阮廷和
Original assignee: OK International Inc
Current assignee: OK International Inc
Priority date: 2019-03-26
Filing date: 2019-11-26
Publication date: 2020-10-09

Abstract

The present invention provides a soldering iron with automatic variable temperature control, comprising: a handpiece or robotic arm including a welding cartridge having a welding horn, a coil generating a magnetic field, and a temperature sensor for sensing a temperature of the welding horn; a variable power source for delivering variable power to the coil to heat the welding horn; a processor including associated circuitry for accepting a set temperature input and the sensed temperature of the welding horn and providing control signals to control the variable power supply to deliver appropriate power to the coil to maintain the temperature of the welding horn at a substantially constant level of the set temperature input.

Description

Variable temperature controlled soldering iron

Cross Reference to Related Applications

This application is a partial continuation of U.S. patent application 16/365,279 filed on 26.3.2019, U.S. patent application 16/365,279 is a partial continuation of U.S. patent application 15/450,425 filed on 6.3.3.2017, U.S. patent application 15/450,425 is a partial continuation of U.S. patent application serial No. 15/333,590 filed on 25.10.2016, U.S. patent application serial No. 15/333,590 is a partial continuation of U.S. patent No. 9,511,439 on 15/096,035.4.11.2016, U.S. patent No. 9,511,439 is a partial continuation of U.S. patent No. 14/966,975 filed on 11.12.2015, U.S. patent No. 9,327,361, U.S. patent No. 9,327,361 is a partial continuation of U.S. patent No. 14/794,678 filed on 8.7.2015. 9,516,762, U.S. patent No. 9,516,762 claims the benefit of U.S. provisional patent application serial No. 62/033,037 filed on 8/4/2014, which is expressly incorporated herein by reference in its entirety.

Technical Field

The disclosed invention relates generally to the manufacture, repair, and rework of Printed Circuit Boards (PCBs) using soldering, and more particularly to soldering irons having automatic variable temperature control.

Background

As the variety of components used on Printed Circuit Boards (PCBs) increases, passive components become smaller and ICs with finer pitch dimensions become larger, and the demand for high quality solder joints that facilitate PCB assembly (PCBA) manufacturing and rework increases. Over the years, wrong solder joints have lost billions of dollars to companies. Many processes have been developed to reduce the failure rate for wave soldering systems. However, for point-to-point hand-held welding and rework applications, companies rely on operator skill to produce good weld joints with good quality electrical connections. Regardless of how much training is provided to the operator of the soldering iron, without guidance during the soldering activity, the operator may make a mistake and repeat the mistake due to the fact that there are many factors that affect the heat transfer through the soldering iron to form a solder joint with a good electrical connection. These factors include weld head temperature, weld head geometry, oxidation of the weld, human behavior, and the like.

Further, automatic (e.g., robotic) welding is an event that is currently strictly based on open loop time, wherein the robot moves to a particular joint, automatically places the welding head on the joint, automatically applies the weld, and after a prescribed time (determined by the specific software for the robot), automatically removes the welding head from the joint. This process is repeated until the robot program is completed.

Heating of the welding head is typically performed by passing a (fixed) current from a power source through a resistive heating element. However, different welding applications require different heating temperatures. Since a single horn with a particular alloy is capable of generating heat at a certain (maximum) temperature, different welding heads are required for different heating applications. A simple soldering iron reaches a temperature level determined by the thermal equilibrium, which depends on the power (current) input and the material of the workpiece in contact with the soldering iron. However, when the horn contacts a large workpiece, such as a large mass of metal, the horn temperature drops, and thus for welding large workpieces, a small horn may lose a large amount of temperature. More advanced soldering irons have a mechanism with a temperature sensor to keep the temperature of the soldering tip steady at a constant level by delivering more power to the soldering tip as the temperature of the soldering tip decreases.

Typically, the variable power control changes the equilibrium temperature of the horn without automatically measuring or adjusting the temperature. Other systems use thermostats, typically inside the soldering iron's soldering tip, which automatically turn power on and off to the cartridge/tip. A thermocouple sensor may be used to monitor the temperature of the horn and adjust the power delivered to the heating element of the cassette to maintain a desired constant temperature.

Another approach is to use a magnetized welding horn that loses its magnetic properties at a particular temperature (curie point). The method depends on the electrical and metallurgical properties of the particular bond head material. For example, the soldering tip may include copper as a material having high electrical conductivity and another magnetic material (metal) having high electrical resistivity. As long as the welding horn is magnetic, the welding horn is in proximity to the switch for the power source and heating element. When the temperature of the horn exceeds the desired temperature (for a particular application), the horn will open the switch and thus the horn begins to cool until the temperature drops sufficiently to restore magnetization of the horn material. Selecting a material with a fixed curie point results in a heater that generates and maintains a specific, self-regulating temperature and constant level, and therefore the heater does not require calibration. That is, when the heater temperature drops (when the heater contacts a thermal load), the power supply will respond with sufficient power to increase the horn temperature back to a fixed desired temperature to properly weld the workpiece. Also, a particular horn of a particular alloy having particular magnetization properties is capable of generating heat at or up to a certain temperature. Thus, different welding horns are required for different heating applications. This requires inventory and maintenance of a variety of different welding horns having different thermal characteristics. This also adds a significant amount of time to the welding process for sufficiently large workpieces or workpieces having different types of components requiring different welding heads, as the operator must continually change the welding heads.

Disclosure of Invention

In some embodiments, the disclosed invention is a soldering iron system with automatic variable temperature control. The soldering iron system comprises: a handpiece or robotic arm including a welding pod having a welding horn, a heating coil, and a temperature sensor for sensing the temperature of the welding horn; a variable power supply for delivering variable power to the heating coil to heat the welding horn; a processor including associated circuitry for accepting a set temperature input and the sensed temperature of the welding horn and providing control signals to control the variable power supply to deliver appropriate power to the heating coil to maintain the temperature of the welding horn at a substantially constant level of the set temperature input.

In some embodiments, the disclosed invention is a soldering iron system with automatic variable temperature control. The soldering iron system comprises: a handpiece or robot arm including a welding pod having a welding horn, a heating coil, and an impedance measuring device for measuring the impedance of the welding horn; a variable power supply for delivering variable power to the heating coil to heat the welding horn; a processor including associated circuitry for accepting a set temperature input and a measured impedance of the welding horn, determining a temperature of the welding horn based on the measured impedance, and providing control signals to control the variable power supply to deliver appropriate power to the heating coil to maintain the temperature of the welding horn at a substantially constant level of the set temperature input.

In some embodiments, the disclosed invention is a soldering iron system with automatic variable temperature control. The soldering iron system comprises: a handpiece or robot arm including a welding pod having a welding horn, a heating coil; a variable power supply for delivering variable power to the heating coil to heat the welding horn; a processor including associated circuitry for accepting a set temperature input and a measured impedance of the welding horn, determining the impedance of the welding horn by disconnecting power to the welding horn and measuring a voltage of the coil, determining a temperature of the welding horn from the measured impedance, and providing a control signal to control the variable power supply to deliver appropriate power to the heating coil to maintain the temperature of the welding horn at a substantially constant level of the set temperature input.

In some embodiments, the set temperature input can be adjusted by an operator of the soldering iron system or can be automatically adjusted by the processor based on one or more of the following: a cassette type, a horn size, a horn shape, a heat load type or size, and a quality of a weld joint formed by the welding horn and determined by the processor.

In some embodiments, the processor determines the quality of the weld joint by determining a thickness of an intermetallic compound (IMC) of the weld joint and determining whether the thickness of the IMC is within a predetermined range.

The automatic variable temperature control of the disclosed invention may be used in a hand-held soldering iron or in an automated (robotic) soldering station for soldering workpieces.

During the welding process, the weld joint may be randomly welded. The welding information data is collected for each welding operation, but the welding identification information is not collected, so it is not possible to know which welding joint is being processed. Accordingly, another aspect of the present invention is directed to a smart welding handpiece comprising: a housing; welding a welding head; a heater for heating the welding horn; a processor for receiving an image of a weld joint being welded by the intelligent welding handpiece, determining weld joint information, and associating the image of the weld joint with the determined weld joint information to distinguish the determined weld joint information for each respective joint.

One or more implementations of the aspects described immediately above include one or more of the following: a camera associated with the handpiece, the camera obtaining an image of a weld joint being welded; the handpiece includes a distal portion with a camera; the camera is an internal camera; the internal camera device comprises a wiring and an electronic device inside the shell; the image pickup device is an external image pickup device; the external camera device comprises a wiring and an electronic device outside the shell; the processor receives an image of the welding horn being welded before welding of the weld joint occurs and receives an image of the welding horn being welded after welding of the weld joint occurs; the processor receives an image of a weld joint being welded while welding of the weld joint occurs; and/or the processor determines a thickness of an intermetallic compound (IMC) of the weld joint being formed by the welding horn, generates an indicator signal indicating that a reliable weld joint connection is formed when the thickness of the IMC is within a predetermined range, and associates an image of the weld joint with the indicator signal.

In some embodiments, the disclosed invention is a soldering iron system with automatic variable temperature control, the soldering iron system comprising: a handpiece or robotic arm including a welding cartridge having a welding horn, a coil generating a magnetic field, and a temperature sensor for sensing a temperature of the welding horn; a variable power source for delivering variable power to the coil to heat the welding horn; a processor including associated circuitry for accepting a set temperature input and the sensed temperature of the welding horn and providing control signals to control the variable power supply to deliver appropriate power to the coil to maintain the temperature of the welding horn at a substantially constant level of the set temperature input.

One or more implementations of the aspects described immediately above include one or more of the following: the temperature sensor is a temperature sensor for sensing the temperature of the welding horn and the processor includes associated circuitry for accepting a set temperature input and the sensed temperature of the welding horn and providing control signals to control the variable power supply to deliver appropriate power to the coil to maintain the temperature of the welding horn at a substantially constant level of the set temperature input; the control signal is a pulse width modulation signal to control the output power of the variable power supply; the set temperature input is adjustable by an operator of the soldering iron system; the set temperature input can be automatically adjusted by the processor based on one or more of: a cassette type, a horn size, a horn shape, a heat load type or size, and a quality of a weld joint formed by the welding horn and determined by the processor; the processor determines a quality of the weld joint by determining a thickness of an intermetallic compound (IMC) of the weld joint and determining whether the thickness of the IMC is within a predetermined range; the processor generating an indication signal indicating that a reliable weld joint connection is formed and transmitting the indication signal when the thickness of the IMC is within a predetermined range; the coil receives high-frequency alternating current, and generates electromagnetic induction through eddy current to heat a welding head serving as a conductive object; the weld box includes a memory that stores unique PID factors to maximize thermal performance; the solder cartridge includes a plurality of solder cartridges, each solder cartridge of the plurality of solder cartridges including a memory storing a unique PID factor to maximize thermal performance; and/or soldering iron systems use temperature sensors to control different temperature set points.

Drawings

Fig. 1A depicts an exemplary hand-held soldering iron according to some embodiments of the disclosed invention.

FIG. 1B is an exemplary block diagram of a processor and related components in accordance with some embodiments of the disclosed invention.

FIG. 1C depicts an exemplary handheld soldering iron in which a processor and associated circuitry are in a power supply, according to some embodiments of the disclosed invention.

FIG. 1D illustrates an exemplary handheld soldering iron in which a processor and associated circuitry are in a hand piece, according to some embodiments of the disclosed invention.

FIG. 1E illustrates an exemplary hand-held soldering iron in which the processor and associated circuitry are in a cartridge, according to some embodiments of the disclosed invention.

FIG. 1F illustrates an exemplary hand-held soldering iron in which a processor and associated circuitry are in a workstation, according to some embodiments of the disclosed invention.

FIG. 1G depicts an exemplary automated welding station, according to some embodiments of the disclosed invention.

Fig. 1H depicts an exemplary circuit for a soldering iron to variably control and set the temperature of a solder tip, according to some embodiments of the disclosed invention.

FIG. 1I depicts an exemplary handheld soldering iron system in accordance with another embodiment of the disclosed invention.

FIG. 1J is a perspective view of an embodiment of various components of a soldering iron of the handheld soldering iron system of FIG. 1I.

FIG. 1K is a perspective view of an embodiment of a soldering iron hand piece and various components of the handheld soldering iron system of FIG. 1I.

FIG. 2 illustrates an exemplary process flow according to some embodiments of the disclosed invention.

Fig. 3A illustrates a graph of temperature versus time for a welding horn for three given load sizes, according to some embodiments of the disclosed invention.

Fig. 3B depicts a graph of the impedance of a welding horn over time for three given power levels and three given temperatures, according to some embodiments of the disclosed invention.

Figure 4A illustrates a graph of thickness versus time of an IMC, in accordance with some embodiments of the disclosed invention.

FIG. 4B illustrates a graph of thickness versus weld time for an IMC in accordance with some embodiments of the disclosed invention.

Fig. 4C shows the IMC layers for a welding event.

Fig. 5 is an exemplary process flow for liquidus detection and connection verification using images from multiple cameras according to some embodiments of the disclosed invention.

Fig. 6A-6D illustrate various images for detecting a liquidus line according to some embodiments of the disclosed invention.

Fig. 7A illustrates some exemplary weld joints for a through-hole component, according to some embodiments of the disclosed invention.

Fig. 7B depicts some exemplary solder joints for surface mount components, according to some embodiments of the disclosed invention.

Fig. 8 illustrates an exemplary smart solder cartridge, in accordance with some embodiments of the disclosed invention.

FIG. 9 is a perspective view of another embodiment of a hand-held soldering iron including a hand piece having a distal end portion including an external camera.

FIG. 10 is a perspective view of yet another embodiment of a hand-held soldering iron including a hand piece having a distal end portion including an internal camera.

Detailed Description

In some embodiments, the disclosed invention is a welding station with automated weld connection verification. The welding station includes a processor, such as a microprocessor or controller, memory, input/output circuitry, and other necessary electronic circuitry to perform weld connection verification.

In some embodiments, the processor receives various characteristics of the solder joint and the soldering station and performs a process to calculate an intermetallic compound (IMC) thickness of the solder and the PCB substrate to ensure a good solder joint is formed during the soldering event. Once a good electrical connection of the weld joint is confirmed, an audio, LED, or vibration indicator in the welding station, such as in the handpiece or on a display in the welding station, will inform the operator or welding robot program that a good weld joint is being formed. Generally, a good solder joint formed by SAC (tin-silver-copper) solder and copper substrate PCB is when the intermetallic thickness of the solder is between 1um and 4 um. Thus, if the bonding station uses, for example, SAC305 (96.5% Sn, 3% Ag, 0.5% Cu) bond wires with a copper substrate PCB, then Cu is calculated by the disclosed invention₆Sn₅Thickness of IMC ofAnd the operator or robot is notified once the IMC thickness of the solder reaches 1um to 4um during the soldering event.

The chemical reaction between the copper substrate and the solder can be shown as:

3Cu+Sn->Cu₃sn (stage 1) (1)

2Cu₃Sn+3Sn->Cu₆Sn₅(stage 2-IMC thickness 1um to 4um) (2).

Phase 1 of the chemical reaction is transient (transient) and therefore not used to determine the quality of the weld joint.

FIG. 1A depicts an exemplary hand-held soldering iron according to some embodiments of the disclosed invention. As shown, the hand-held soldering iron includes a power supply unit 102, the power supply unit 102 including a display 104, such as an LCD display, and various indicators 106, such as

LED indicators

106a and 106 b. Other indicators such as sound emitting devices or tactile devices may also be used. The soldering iron further comprises a hand piece 108 coupled to the power supply unit 102 and a (work) table 110 accommodating the hand piece 108. The handpiece 108 receives power from the power supply unit 102 and heats a welding horn attached to or located in a welding pod to perform welding on a workpiece. In some embodiments, the weld cartridge may include a temperature sensor thermally coupled to the welding horn to sense the horn temperature and send this data to the processor.

The handpiece 108 may include various indicators thereon, such as one or more LEDs and/or a buzzer. In some embodiments, the power supply unit 102 or the handpiece 108 includes a microprocessor, memory, input/output circuitry, and other necessary electronic circuitry to perform various processes. Those skilled in the art will recognize that the microprocessor (or controller) may be placed in the power source, in the handpiece, or in the station of the welding system. Known wired and/or wireless interfaces and protocols can be used to communicate with external devices, such as local computers, remote servers, robots for performing welding, printers, etc., at the workstation via wired and/or wireless connections.

In some embodiments, the microprocessor and associated circuitry identifies which solder pot is being used, verifies the solder head geometry, verifies the temperature and load (solder joint) match to ensure that the selected solder pot can generate enough energy to bring the load to the melting point of the solder, detects the liquidus temperature and then determines the IMC thickness of the solder, as described in more detail below. For example, if the solder head geometry is too small for the load, the solder head will not be able to bring the joint to the solder melting point. The liquidus temperature is a temperature above which the material is completely in a liquid state. The liquidus temperature is mainly used for impurities (mixtures) such as glass, alloys and rocks. Above the liquidus temperature, the material is homogeneous and liquid at equilibrium. Below the liquidus temperature, depending on the material, crystals form in the material after a sufficient time.

Fig. 8 illustrates an exemplary smart solder cartridge, in accordance with some embodiments of the disclosed invention. In some embodiments, the smart solder cartridge includes a solder horn 802, associated wiring 804, a magnetic shield 806, a heater 808 for heating the horn, a shaft or housing 810, a connector 812 for both electrical and mechanical connection, and a storage device 814, such as a non-volatile memory (NVM). The smart welding cartridge may also include one or more sensors 818, such as a temperature sensor for measuring the temperature of the horn and/or a potentiometer for measuring the impedance of the horn, a Radio Frequency Identification Device (RFID)820, and/or a processor and associated circuitry 816, such as input/output circuitry and wired and/or wireless interfaces for data communication. A mechanical connector (not shown) for connecting the cassette to a handpiece or robotic arm may be included for efficient, quick-release operation.

In some embodiments, a cartridge ID, such as a serial number or code unique to a particular cartridge, is read from the NVM 814 or RFID 820 to identify the cartridge, the type of cartridge, and related parameter and specification information. The NVM 814 can also store information regarding the temperature of multiple welding heads over time, similar to the graphs of fig. 3A, 3B, 4A, and 4B. Once a particular welding horn is used, information about the temperature change of the welding horn being used is obtained from the NVM. Typically, during a welding event, the temperature of the horn may drop as the weld joint is heated and thus the heater needs to re-heat the horn, which typically results in exceeding the temperature required (set) for the horn. However, in some embodiments, the temperature sensor 818 periodically senses the temperature of the horn and feeds information to the processor (or directly to the heater 808) to adjust the temperature in the event of any temperature drop (or increase) due to load or other factors. In this way, a modest amount of heat is transferred directly to the weld joint.

In some embodiments, the NVM and/or the RFID stores data relating to characteristics of the cartridge such as part number, lot code, serial number, total usage, total number of points, bond head quality/weight, bond head configuration, authentication code (if any), thermal efficiency, thermal characteristics, etc. This data may be acquired by a processor (e.g., internal processor 816 or an external processor) periodically at start-up and during the welding operation. In some embodiments, data may also be received and transmitted via wired or wireless methods.

In some embodiments, the NVM and/or RFID of the cartridge includes all or some of the following information.

1. Temperature of the heater/horn and optionally information about temperature changes over time for various load sizes;

2. the soldering tip geometry, which may include the contact surface of the soldering tip with the solder, the distance of the soldering tip from the heater, the quality of the soldering tip;

3. thermal efficiency factor of the horn (based on mass, shape, heater, etc.);

4. the number of welding events that have been performed by a particular horn, which can be used for traceability;

5. time of horn use (e.g., total time of horn use for warranty and traceability);

6. date of manufacture of the cartridge;

7. a serial number and an identification code for the cartridge;

8. a part number;

CV select flag (whether the horn and/or cassette uses CV techniques);

10. data checksum;

11. having a different proportional-integral-derivative controller ("PID") factor for each cartridge to maximize thermal performance;

as explained below, the bond head temperature, bond head geometry, and thermal efficiency are used to calculate an approximation of the IMC layer thickness. As explained below, the number of welding events, the time of use of the welding head, and the date of manufacture can be used to further refine the IMC thickness calculation process. Historical information such as time of use, number of welding events, etc. may be written back to the NVM to be accumulated.

The serial number, part number, and CV select flags are used for internal custody, traceability, and/or to determine whether a process will/should provide a valid indication of IMC formation. In some embodiments, the data checksum may be used to determine whether there is a failure in the NVM or whether there is a communication data transfer error. In some embodiments, a smart pod for a robotic welding station includes an anti-rotation D-ring for preventing unwanted rotation of the pod while the robotic arm is rotating.

In some embodiments, the smart solder box is capable of performing the process of liquidus detection and connection verification according to the two process flows of fig. 2 and 5. For example, the processor 816 can obtain information from the NVM or the RFID regarding characteristics of the cartridge, detect the occurrence of a liquidus at the solder joint, receive a 3D current image of the solder joint, determine a volume of solder dispensed after the liquidus has occurred from the 3D current image, compare the volume of solder dispensed to an amount of solder required for a surface of a canister for a through-hole component fill hole or a canister for a surface mount component fill hole to determine how much solder dispensed is spread onto a surface area of the canister or canister, repeat the comparison of the volumes of solder dispensed until the solder dispensed fills the surface area of the canister or canister, and generate an indication signal indicating that a reliable solder joint connection is formed when the solder dispensed fills the surface area of the canister or canister within a predetermined tolerance.

Additionally, the processor 816 may be capable of obtaining information regarding characteristics of the cartridge, detecting the appearance of a liquidus at the solder joint, receiving a 3D current image of the solder joint, determining a volume of solder dispensed upon appearance of the liquidus from the 3D current image, comparing the volume of solder dispensed to an amount of solder required for a surface of a barrel for a through-hole component fill hole or a barrel for a surface mount component fill hole to determine how much solder dispensed is spread onto a surface area of the barrel or barrel. The processor may then repeatedly compare the volume of dispensed solder until the dispensed solder fills the canister or surface area of the canister and generate an indicator signal indicating that a reliable solder joint connection is formed when the dispensed solder fills the canister or surface area of the canister within a predetermined tolerance.

FIG. 1B is an exemplary block diagram of a processor and related components in accordance with some embodiments of the disclosed invention. As shown, processor 112, memory 114, non-volatile memory (NVM)116, and I/O interface 118 are coupled to bus 120 to include the processor and associated circuitry of some embodiments of the disclosed invention. The I/O interface 118 may be a wired interface and/or a wireless interface to components external to the welding station. Optionally, one or

more cameras

122 and 124 are coupled to the processor and memory via the bus 120 or the I/O interface 118 to capture images from the weld joint from various angles. Additionally, an optional temperature sensor 126 for sensing the temperature of the welding horn may be coupled to the processor 112 and the memory 114 via the bus 120 or the I/O interface 118. The optional temperature sensor may be located at or near the welding horn.

As those skilled in the art will readily appreciate, the different components depicted in FIG. 1B may be located in different parts of the soldering iron or automated soldering station, as described in the following sections. For example, the camera may be located external to or separate from various components of the soldering iron or automated soldering station, while the processor and associated circuitry may be located in any component of the soldering iron or automated soldering station (as described below). The sensors may also be located in/at different parts of the soldering iron or automatic soldering station depending on their application.

FIG. 1C depicts an exemplary handheld soldering iron in which a processor and associated circuitry are in a power supply, according to some embodiments of the disclosed invention. As shown, the power supply unit includes a processor and associated circuitry and an internal power monitoring unit/circuit to detect and vary the power supplied by the power supply to the handpiece, cartridge and/or welding horn. The power supply unit also includes a wired and/or wireless interface to electronically communicate with the handpiece, LED, cartridge, and/or external device. Once the processor determines the quality of the weld joint, the processor outputs an appropriate signal to activate one or more of the LED, sound emitting device, and haptic device to inform the operator about the determined quality of the weld joint.

In addition, a cartridge ID, such as a serial number or code unique to a particular cartridge, is read from the cartridge's memory (e.g., NVM or RFID) to identify the cartridge and its type. This may be done through a wired connection or a wireless connection. For example, with an RFID inside the cartridge, the RFID (or even the NVM) can be read wirelessly (by the processor). Once the smart solder cartridge and its type are identified, the relevant parameters of the cartridge are retrieved by the processor from memory, such as an EEPROM. The storage of cartridge-related parameters may be inside or outside the cartridge. In some embodiments, if all relevant (cartridge) parameters are stored in the memory (which is within the cartridge), the cartridge may not need to be specifically identified since the parameters are already available in the memory of the cartridge and are cartridge specific.

In some embodiments, the cartridge may have a bar code, magnetic strip, or "smart chip" to identify the cartridge. Once the cartridge is identified, the relevant information may be read from a bar code, magnetic strip, smart chip or retrieved from an external storage device such as a memory or database coupled to a computer network such as the internet. For purposes of this application and the claimed invention, the storage device will also include bar codes, magnetic strips, and smart chips.

FIG. 1D illustrates an exemplary handheld soldering iron in which a processor and associated circuitry are in a hand piece, according to some embodiments of the disclosed invention. The general function and operation of these embodiments are similar to those described with respect to fig. 1C, except that the processor (and associated circuitry) and power monitoring unit/circuitry are now located with the handpiece.

FIG. 1E illustrates an exemplary hand-held soldering iron in which the processor and associated circuitry are in a cartridge, according to some embodiments of the disclosed invention. In these embodiments, the cartridge may be similar to the smart cartridge described in fig. 8 and described above. The general function and operation of these embodiments are similar to those described with respect to fig. 1C, except that the processor (and associated circuitry) and memory are now located with the cartridge. Also, the communication between the cartridge, the handpiece, and the external device may be wired and/or wireless. As will be readily appreciated by those skilled in the art, the power monitoring unit/circuit (not shown) may be located in the power supply unit, the handpiece, or the case itself. In these embodiments, the means of notifying the operator (e.g., an LED, sound emitting device, and/or tactile device) may be located with the handpiece or the case itself. If the means of notifying the operator is located with the handpiece, the handpiece includes a wired interface and/or a wireless interface to communicate with the cartridge (and any associated external devices).

FIG. 1F illustrates an exemplary hand-held soldering iron in which a processor and associated circuitry are in a workstation, according to some embodiments of the disclosed invention. The general function and operation of these embodiments are similar to those described with respect to fig. 1C, except that the processor (and associated circuitry) and power monitoring unit/circuitry are now located with the soldering iron's table.

FIG. 1G illustrates an exemplary automated welding station, according to some embodiments of the disclosed invention. In these embodiments, the handpiece and cassette are assembled on or part of a robotic arm as shown. As shown, the robotic arm 140 is capable of three-dimensional movement and rotation. The handpiece 144 is coupled to the robotic arm and a smart welding cartridge, such as the smart welding cartridge according to fig. 8, is connected to the handpiece. In some embodiments, the smart welding cartridge 142 may be directly coupled to the robotic arm 140 that will act as a handpiece.

A workpiece 154, such as a Printed Wiring Board (PWB), is placed on a moving platform 156 to perform a soldering operation on the platform 156. The solder feeder 146 provides solder to the workpiece 154 via a handle, anchor, roller or tube 148. One or more cameras 152 placed at different angles capture the closure of the weld joint on the workpiece. The power supply 150 provides power to the cartridge and associated electronics in the cartridge.

In this way, the CV technique of the disclosed invention is capable of providing feedback to any conventional automated welding station (closed loop system). For example, by providing real-time feedback of weld quality, the open loop time-based events of the conventional method are significantly improved. That is, CV techniques provide the robot motion control system with a feedback signal that indicates when a good joint is made, rather than using a prescribed time for the weld joint. In some embodiments, the robot may move to the next joint in the program only if the joint is indicated to be good. When a poor joint is made, the robot may stop immediately or at the end of the procedure and alert the operator to problems with the welded joint.

Fig. 1H depicts an exemplary circuit for a soldering iron to variably control and set the temperature of a solder tip in accordance with some embodiments of the disclosed invention. As shown, the variable power supply 162 delivers power to a coil 165 of a welding handpiece or robotic arm 164 to heat the coil. The heat of the coil 165 is then transferred to the welding horn 166. The handpiece or robotic arm 164 includes a temperature sensor 172 to measure the temperature of the weld head and/or an impedance measuring device 172, such as a potentiometer, to measure the impedance of the weld head, according to methods described below. If a temperature sensor, the sensor may be a contact or non-contact sensor for measuring the temperature of the bonding tool.

A processor 169 having associated circuitry and programming then receives the temperature measurement information 167 and/or the impedance measurement information 168. Additionally, the processor 169 also receives temperature setting information 170. Based on the temperature setting information 170, the temperature measurement information 167, and/or the impedance measurement information 168, the processor 169 controls (via control signals 171) the variable power supply 162 to deliver the required power set by the temperature setting information 170 to the coil 164 such that the coil maintains a constant temperature at the set temperature. The output power of the variable power supply 162 may be varied based on a variation of its output voltage or a Pulse Width Modulation (PWM) control signal 171. Well known PWM regulate the output of the power supply 162 by switching the voltage delivered to the coil 164 at an appropriate duty cycle, which approximates the voltage at the desired level (and resulting weld head temperature).

In some embodiments, the temperature setting information 170 is provided by an operator according to a desired temperature for the application. In some embodiments, the temperature setting information 170 is automatically set and changed (adjusted) by the processor 169 according to one or more of cassette type, horn size, horn shape, heat load type or size, and the quality of the connection as determined by the verification process described below.

In this way, the same welding horn may be used for different heating applications, resulting in reduced inventory and maintenance of various different welding horns and reduced welding time for large workpieces or components having different types requiring different horns.

With reference to fig. 1I-1K, an exemplary handheld soldering iron system 174 with automatic variable temperature control in accordance with embodiments of the disclosed invention will be described.

Soldering iron system 174 with automatic variable temperature control includes a hand piece 176 including a shaft 177 and a solder cartridge 178 having a solder tip 180, a coil 182 for generating a magnetic field, a magnetic shield 183, and a temperature sensor for sensing the temperature of the solder tip 180 or an impedance measuring device 184 for measuring the impedance of the solder tip 180. Soldering iron system 174 includes an RF variable power source 186 for delivering variable power to coil 182 to heat welding tip 180 via the skin effect. A high-frequency alternating current is passed through the coil 182 to generate electromagnetic induction by eddy current to heat the bonding tool 180, which is an electrically conductive object. The (work) table 187 receives the hand piece 176. A connector 188 having a chip including a processor and associated circuitry accepts a set temperature input and a sensed temperature of the welding horn 180 and provides control signals to control the RF variable power source 186 to deliver appropriate power to the heating coil 182 to maintain the temperature of the welding horn 180 at a substantially constant level of the set temperature input. The welding horn holder 190 covers the welding horn 180.

In another embodiment, to make the handheld soldering iron system 174 more accurate and powerful, each soldering cartridge 178 includes a memory (e.g., NVM 814, RFID 820) built into the cartridge 178 that stores a different PID factor for each cartridge 178 to maximize thermal performance.

The handheld soldering iron system 174 uses the temperature sensor 184 to control a different temperature set point (i.e., any desired temperature set point) rather than using the curie point to obtain a fixed temperature as in the past induction heating handheld soldering iron systems. In the handheld soldering iron system 174, due to the transient response of induction heating, the solder cartridge 178 is used which stores a unique PID factor in each of the different cartridges to outperform the conventional curie point fixed temperature and avoid excessive exceeding damage to the electronic components, and the heat is controlled based on the sensed temperature, superior to past induction heated handheld soldering iron systems which use the curie point to obtain the fixed temperature.

FIG. 2 illustrates an exemplary process flow according to some embodiments of the disclosed invention. As shown in block 202, a process for verifying all connection joints between a component and a PCB substrate is initiated. In block 204, the cartridge being used is identified and data relating to the identified cartridge is retrieved from a non-volatile memory (NVM) such as EEPROM in or external to the cartridge. As described above, in some embodiments, data relating to the identified cartridge is retrieved by the processor from the NVM in the cartridge.

In block 206, the process (e.g., processor) checks the power level to determine if any welding actions are being performed over a period of time. If there are no more welding actions to be performed, the process waits in block 206. For example, a timer may be set to a predetermined time and if no action occurs within that time, the process waits. However, if a welding action is to be performed, the process proceeds to optional block 208, where the indicator is reset at optional block 208.

Fig. 3A shows a graph of temperature versus time for a welding horn for three given solder load sizes. As described above, this data may be stored in the memory of the cartridge. Graph 306 is for a large load size (e.g., -104 Cu Mil)²) Graph 304 is for a medium load size (e.g., -54 Cu Mil)²) And graph 302 illustrates small load sizes (e.g.，～24CuMil²). As shown in fig. 3A, the heavier the load, the greater the temperature drop for a given horn. In some embodiments, if the temperature of the horn drops above a predetermined value, e.g., about 25 ℃ (as determined from experimental data), the process is aborted because the power supply will not be able to resume quickly enough to continue to deliver power to the horn for the required time (e.g., 8 seconds) to complete the welding event to maintain the temperature of the horn.

In some embodiments, the temperature drop may be detected by measuring the impedance of the horn and then determining the horn temperature by equation (3) below. The impedance may be measured by disconnecting power to the cartridge/weld head and measuring the voltage of the coil (in the cartridge) in thermal contact with the weld head. The impedance of the horn will then be the voltage of the coil multiplied by an impedance weighting factor (K in equation (3)) that depends on the horn type and is stored in a memory, for example in the cartridge itself. In some embodiments, a temperature sensor may be placed in the cassette to directly read the temperature drop of the bonding tool and transmit the temperature drop of the bonding tool to the microprocessor.

R_imd＝+R_max/(1+[k*e^(-T)]) (3).

Wherein R is_imdIs the resistance value, R_minIs the minimum value of the impedance, R_maxIs the maximum value of the impedance, K is the weighting factor and T is the temperature difference, i.e. the temperature difference between the horn and the load. The weld head temperature drop is typically due to heat transfer from the weld head to the load at the beginning and may vary between 6 ° and 48 ° depending on the weld head geometry, heater, and type of weld head. R_minIs the minimum impedance value of the welding horn prior to turning on power at start-up. R_maxIs the maximum impedance value of the welding horn after a predetermined amount of time, e.g., 2 seconds, of power being turned on at startup. These values are specific to the particular welding horn being used and are stored in a memory accessible to the processor.

Fig. 3B depicts a graph of the impedance of the welding horn over time for three given power levels and three given temperatures of the welding horn delivered to the welding horn by the power supply unit. As explained above, this data may also be stored in the memory of the cartridge. Graph 318 is for low power, graph 312 is for high power and graph 314 shows medium power. Further, graph 310 is for small temperatures, graph 316 is for medium temperatures and graph 320 is for large temperatures.

In some embodiments, the temperature drop may be detected by defining a thermal efficiency factor for each given horn geometry and heater material (stored in a memory in or external to the cartridge), as shown in equation (4) below. If the power consumed is above the TE factor, the system determines that the process is aborted by, for example, turning on a red LED, activating a haptic device, or activating a sound emitting device.

TE factor (mass of the weld head) pattern (HTR factor) constant (4),

where the horn mass is the weight of copper (mg), 0.65 for a long horn, 1 for a conventional horn and 1.72 for a power horn. The horn pattern refers to the distance from the head of the horn to the heater in the cartridge. For example, according to the data for some welding horns currently available on the market, the horn style is 20mm for "long" horns, 10mm for "conventional" horns and 5mm for "power" horns. The HTR _ factor is the heater temperature multiplied by a factor (e.g., 0.01) that is given (predetermined) based on the type of heater. For all types of heaters, the constant 4.651 x 10^-3. For example, the HTR _ factor may be 800F 0.01 — 8 for various heater types; 700F 0.01 ═ 7; 600F 0.01 ═ 6 or 500F 0.01 ═ 5. These parameter values may be stored in a memory (e.g., NVM) of the soldering iron, the soldering station, or in a memory within the cartridge itself.

Referring back to fig. 2, in block 210, a thermal efficiency check is performed to ensure that the horn geometry/temperature matches the load based on the horn temperature drop (e.g., according to equation (3) or equation (4) or a temperature sensor) over a predetermined period of time, e.g., the first 2 to 3 seconds of a welding event. For example, there is a match when the maximum power 2 seconds after welding is less than or equal to the thermal efficiency factor of the welding horn being used. The parameters may be retrieved from the NVM.

In some embodiments, the thermal efficiency inspection process monitors the heat transfer and power recovery of the welding station with respect to the horn and load. Each horn type has its own thermal characteristics that are a function of the horn temperature, quality, and configuration/style. For each bond head type, their thermal characteristics and efficiency factors (TE) are stored in a memory in or external to the cassette.

During a first time period (e.g., 2-3 seconds), power to the horn (e.g., from a power source) is measured and compared to the TE of the horn. If the measured power is greater than a threshold, such as 95% +/-10% of the TE factor, it means that the horn is too small or too loaded because they require much power. In this case, the thermal efficiency check fails (210a), and the process aborts and optionally turns on one or more indicators such as red LEDs, tactile devices, and/or sound emitting devices in block 226. If the thermal efficiency check passes (210b), the process proceeds to optional block 212 where a pass indicator, such as a green LED and/or beep, is turned on in block 212 to let the operator or robot program know that the thermal efficiency check process has passed.

In block 214, the liquidus temperature is detected based on the following heat transfer formula.

ΔT＝P*TR (5),

Where Δ T is the bond head temperature minus the load temperature, P is the (electrical) power level to the bond head, and TR is the thermal resistance between the bond head and the load that can be obtained from NVM.

Since the load temperature continues to increase until equilibrium is reached, Δ T decreases throughout the welding action. In addition, when a welding event is first initiated, power to the welding head is increased. Therefore, as shown below, TR will decrease. Once the liquidus occurs, TR stabilizes and thus, as shown below, the power to the weld head P now begins to decrease. Thus, for the detected liquidus temperature, the state of change of the power transmitted to the welding horn is observed.

ΔT↓＝P↑*TR↓

ΔT↓＝P↓*TR～

In block 216, a check is made to see if the power is at a peak and drops. If not, the process times out (216a) and aborts in block 226. If the power measured from the power source to the horn is at a peak and drops, the process proceeds to block 218 to turn on an indicator such as an LED and/or beep. When the power is at a peak and drops, this means that the welding event is in the liquidus state.

In block 220, the thickness of the IMC is determined by the following equation.

IMC＝1+(k*ln(t+1)) (6),

Where k is a weighting factor for the type of solder used (provided by the manufacturer of the solder and stored in memory) and t is the sampling/sensing interval time, e.g., 100ms, to determine the IMC thickness at a given time after the liquidus. For example, K is a constant with a value of 0.2173 and t is 0.1 seconds, that is, the IMC is calculated at intervals of 0.1s to avoid overshoot for small loads. That is, as the horn heats the weld joint, the horn cools, and the temperature may exceed its set (desired) value when the heater attempts to re-heat the horn. Typically, the thickness of the IMC may vary between 1um to 4 um.

Generally, the thickness of the IMC of a weld joint will be a function of time and temperature. When the temperature is at the melting point of the solder load (e.g., at 220 ℃ to 240 ℃), it has no substantial effect on the thickness of the IMC of the solder joint. Therefore, equation (6) is based only on time and fixed temperature.

Fig. 4A shows a graph of thickness of IMC versus time for a solder joint with a weight factor k of 0.2173 obtained experimentally using a number of solder joints and IMC thickness measurements. As depicted in fig. 4A, IMC thickness increased over time based on experimental data.

Referring back to FIG. 2, block 222 checks to see if the determined thickness of the IMC is within a predetermined range, e.g., 1um to 4um, for a predetermined amount of time (cooling period). If so, processing proceeds to block 224 where the operator is notified in block 224. If the result of the test in block 222 is false, the process times out (222b) and aborts in block 226.

In some embodiments, the present invention provides an operator with an indication of successful or potentially unsuccessful joint formation and the ability to collect intermetallic joint information and operating parameters for that particular joint for post-processing. The indication may be accomplished via visual means, audible means, and/or vibration of the handpiece.

For example, and not by way of limitation, fig. 9 and 10 illustrate embodiments of a

camera

900, 910 for a welding handpiece, the

camera

900, 910 may be used to obtain images of a weld joint to determine the joint being machined because in the past, joints were often welded randomly and weld information data was collected for each welding event without knowing which joint was being machined. Elements in fig. 9 and 10 that are similar to those shown and described herein will be shown/described with the same reference numerals but suffixed with "a". The subject matter shown and/or described with respect to fig. 1-8 is incorporated herein. For example, but not by way of limitation, the processor and related components shown and/or described with respect to fig. 1B are incorporated herein.

In the embodiment of fig. 9, the camera 900 is an external camera carried by the handpiece 108a at the distal end 902 of the housing/shaft 810 a. The external image pickup device 900 is coupled to the power supply unit 102a via a line 920, an adapter 930, and a plug/connector 940. In alternative embodiments, the external camera 900 may be located in a portion other than the distal end 902 of the housing/shaft 810 a. For example, but not by way of limitation, external camera 900 may be mounted on a tripod (e.g., on a table) near the welding activity.

In the embodiment of fig. 10, the camera 910 is an internal camera carried by the handpiece 108a at the distal end 902 of the housing/shaft 810a, but unlike the external camera 900, all wiring/electronics for the internal camera 910 are internal to the shaft 810a and/or the power supply unit 102 a. For example, but not by way of limitation, the internal camera 910 may be mounted on the power supply unit 102 a.

In use, the

cameras

900, 910 obtain images of the joint before and after a welding event. The image is correlated with one or more of the welding information collected and/or determined for each joint shown and/or described herein, such that the welding information collected/determined for each respective joint can be distinguished, such as the horn geometry, liquidus temperature, heater/horn temperature, information about the change in horn geometry temperature over time for various load sizes, which may include the contact surface of the horn with the solder, the distance of the horn from the heater, the quality of the horn, the thermal efficiency factor of the horn (based on quality, shape, heater, etc.), the number of welding events that have been performed by a particular horn that can be used for retrospective, the time of use of the horn (e.g., total time of use of the horn for warranty and retrospective), the date of manufacture of the cartridge, the time of use of the cartridge, the time of the cartridge, and, A serial number and identification code for the cartridge, a part number, a CV selection flag (whether the soldering tip and/or the cartridge uses CV technology), a data checksum, detecting the presence of a liquidus at the soldering joint, receiving a 3D current image of the soldering joint, determining from the 3D current image the volume of solder dispensed after the liquidus has occurred, comparing the volume of solder dispensed with the amount of solder required for the surface of the barrel for the through-hole component fill hole or the barrel for the surface mount component fill hole to determine how much solder dispensed is spread onto the barrel or surface area of the barrel, an indicator signal indicating that a reliable soldering joint connection is formed. Alternatively, the

cameras

900, 910 obtain images of the joint during the welding event or before, during, and/or after the welding event.

For example, the commissioning mode (block 228) is used by a process engineer to track steps involved during a welding event. To enter debug mode, the user needs to turn on debug mode.

A similar process for detecting liquidus may be used to remove solder from a solder joint to ensure that all solder is removed from the joint. For example, once the liquidus temperature is detected, the vacuum (automatically or manually) is turned on to remove the solder from the joint. In this way, the vacuum is turned on at the correct time. Because if opened earlier than the liquidus temperature, the solder is not liquid and therefore cannot be removed. Furthermore, if the vacuum is turned on before the liquidus temperature, most of the heat applied to the joint is drawn away by the vacuum.

Fig. 4B shows a graph of thickness versus weld time for IMC. As depicted, graph 402 is for a temperature of 300 ℃, where Y is 0.176X +1.242, graph 404 is for a temperature of 275 ℃, where Y is 0.044X +1.00, and graph 406 is for a temperature of 220 ℃, where Y is 0.049X +0.297, where X is time and Y is IMC thickness. The constants were derived from multiple experiments. As shown, breakthrough of IMC thickness occurs in three different temperature ranges. Since the thickness of the IMC is a function of time and temperature, the IMC increases as the temperature increases as a linear function. Depending on the application, either of these curves can be used to determine the weighting factor K in equation (6). For example, for a welding application with a SAC305 weld head (the specifications of which may be stored in the NVM of the cartridge), the map 404 is used.

Figure 4C shows an IMC layer of size 10 um. The vertical arrows are locations where IMC thickness measurements can be performed. As described above, the disclosed invention detects the liquidus temperature, determines the thickness of the IMC and ensures that the desired thickness is obtained.

In this way, embodiments of the disclosed invention ensure good bonding and electrical connection between two metals by calculating the intermetallic thickness, and thus prevent poor joints at an early stage. Furthermore, the present invention provides immediate feedback to the operator (via the indicator) regarding joint quality and process issues, and thus the operator has the ability to track information regarding joint quality for later analysis. The operator may change or select different parameters from a menu to meet certain application requirements.

In some embodiments, when using self-regulating temperature feedback techniques, no calibration of the system is required on the client side. The present invention also provides the ability to assist operators in identifying whether they are using an improper horn/cassette combination for a welding event. For example, the present invention can notify the operator (e.g., via an LED, sound emitting device, haptic device, etc.) when the welding horn is unable to deliver sufficient energy required to bring the load to the melting point after a predetermined time (e.g., 2 seconds) from start-up based on a thermal efficiency threshold stored in the NVM.

In some embodiments, the present invention uses at least two high resolution cameras to capture two or more 2D images, obtains 3D images from those 2D images (using various known techniques), uses the 2D images and the 3D images to detect the liquidus phase and then calculates the amount of solder filled through the via (barrel) for the through-hole component or distributed around the component for the surface mount component.

Fig. 5 is an exemplary process flow for liquidus detection and connection verification using images from multiple cameras according to some embodiments of the disclosed invention. In some embodiments, at least two high resolution cameras are placed at two different locations near the weld joint to capture 2D images of the weld joint from two perspectives (angles) before and after the welding event. The liquidus is detected from a comparison of the 2D images. Then, in the case of the through hole member, the volume of the through hole cylinder (barrel) is determined from the 3D image generated from the 2D image. In the case of Surface Mount (SMT) components, the surface of the can on the PCB is determined from the 2D image. As shown in block 502, prior to the welding event, two images of the welding area (joint) are captured by two cameras to generate two reference images, as depicted in fig. 6A. In block 504, prior to the welding event, a 3D reference image of the weld region is generated from the two reference images by well-known methods.

In block 506, a volume V of the barrel for the through hole is determined from the 3D reference image_bAnd/or surface area S of the canister for SMT components_bTo determine how much solder is needed to fill the barrel or the surface area of the barrel. From the position of the camera, the surface of the cylinder can also be determined from the 2D image. For example, knowing the distance and angle of each camera relative to the weld joint, the distance of any point (e.g., a point on the perimeter of the can surface) can be determined using simple known trigonometry. Furthermore, having a second (stereo) camera provides at least four points for volume determination. There is also a root of HeiKnown software tools (e.g. computer vision software) measure volumes (and surface regions) from 3D images. For example, from MediaCybernetics^TMImage-Pro Premier 3D of^TMAnd Image-Pro Plus^TMThe properties of a variety of materials within a volume can be measured and easily found in composition percentage, material mass, orientation, diameter, radius and surface area. The tool is capable of measuring object volume, cassette volume, depth, diameter, radius and surface area. Several other tools with similar functions are also available and known to those skilled in the art.

Thus, depending on the type of component, the amount of solder required to fill the barrel or the surface of the barrel is determined. After the welding event begins, two current images of the weld area are captured immediately at block 508. In block 510, as the soldering event progresses, the color value of each pixel in the 2D reference image is compared to the color value of each corresponding pixel in the 2D current image to detect any color change of the pixel in the current image due to spreading of the solder. Since the pixel value of the solder color is known, the process can determine whether the pixel is a solder pixel, i.e., contains solder, as shown in fig. 6B.

In block 512, the process in blocks 508 (fig. 6C) and 510 are repeated until it is determined that all pixels in the current image are pixels of the dispensed solder, i.e., the liquidus is now detected, as depicted in fig. 6D. If it is determined that not all pixels in the current image are pixels of solder, the process in block 512 times out after a predetermined amount of time (e.g., 8 seconds). When all pixels in the two most recent current images are determined to be pixels of the dispensed solder (within tolerance), the liquidus is detected in block 514.

After the liquidus is detected, in block 516, the most recent current image from each camera is processed to generate a 3D current image. Then, in block 518, a volume V of dispensed solder is determined from the 3D current image by one or more of equations (7) through (9)_s. In block 520, the calculated volume V of solder dispensed is compared_sWith the determined filling cylinder (i.e. V)_b) Or surface area of the cartridge (i.e., S)_b) The amounts of solder required are compared to determine how much of the dispensed solder is spread into or onto the surface area of the barrel. The process is repeated in block 522 (block 520) until the dispensed solder has filled the canister or surface area of the canister. That is, the visible volume of dispensed solder has reached (V) within a predetermined tolerance_sV_b) Or (V)_sS_b). The process in block 522 times out after a predetermined amount of time (e.g., 8 seconds). An indicator (e.g., an LED and/or buzzer) is then turned on to notify the operator that a connection is now being made by filling all of the cartridges or surfaces of the cartridges with the dispensed solder.

In other words, in the case of the through-hole component, when the calculated volume is reduced to the predetermined amount required to fill the cartridge and is within the predefined tolerance for the through-hole component, a good weld joint is formed, as shown in fig. 7A. In some embodiments, the calculation of the height and volume of the weld joint is performed based on the following equation.

V_{Lead wire}＝πr_{Lead wire} ²h (7)

V_Cartridge＝πr_Cartridge ²h (8)

V_{Need to make}＝πh(r_Cartridge ²h–r_{Lead wire} ²h) (9)

As shown in FIG. 7A, wherein V_{Lead wire}Is the volume of the component lead; v_CartridgeIs the volume of the through-hole cartridge; v_{Need to make}Is the amount of solder required to fill the canister; r is_{Lead wire}Is the (via) component lead radius; r is_CartridgeIs the through-hole cylinder radius; and h is the plate thickness.

Fig. 7A illustrates some exemplary weld joints for a thru-hole component, images of which are captured by two cameras, according to some embodiments of the disclosed invention. Fig. 7B illustrates some exemplary solder joints for surface mount components, images of which are captured by two cameras, according to some embodiments of the disclosed invention. In this case, the present invention compares the height of the entire load with a predetermined reference height (desired height) to form a parabolic shape or a linear shape. Once the identified shape area is equal to a predefined percentage of the load (barrel) surface area within a predetermined tolerance, a good weld is formed for the surface mount component. As shown in fig. 7B, for larger surface mount components, the solder joints are formed in a parabolic shape on the side of the component. However, for smaller surface mount components, the solder joints are formed in a linear shape on the side of the component due to the small size of the component because the camera device can only capture the area of linear fill.

A similar process for detecting liquidus may be used to remove solder from a solder joint to ensure that all solder is removed from the joint. For example, once the liquidus temperature is detected using the process described above, the vacuum (either automatically or manually) is turned on to remove the solder from the joint. In this way, the vacuum will be turned on at the correct time.

It will be appreciated by those skilled in the art that various modifications could be made to the illustrated embodiments of the invention described above, as well as other embodiments, without departing from the broad inventive step of the present invention. It is understood, therefore, that this invention is not limited to the particular embodiments or arrangements disclosed, but is intended to cover any changes, adaptations or modifications that are within the scope and spirit of the invention as defined by the appended claims.

Claims

1. A soldering iron system with automatic variable temperature control, comprising:

a handpiece or robotic arm including a welding cartridge having a welding horn, a coil generating a magnetic field, and a temperature sensor for sensing a temperature of the welding horn;

a variable power source for delivering variable power to the coil to heat the welding horn;

a processor including associated circuitry, the processor for accepting a set temperature input and the sensed temperature of the welding horn and providing control signals to control the variable power source to deliver appropriate power to the coil to maintain the temperature of the welding horn at a substantially constant level of the set temperature input.

2. The soldering iron system according to claim 1, wherein the temperature sensor is a temperature sensor for sensing the temperature of the welding tip and the processor includes associated circuitry for accepting a set temperature input and the sensed temperature of the welding tip and providing control signals to control the variable power supply to deliver appropriate power to the coil to maintain the temperature of the welding tip at a substantially constant level of the set temperature input.

3. The soldering iron system according to claim 1, wherein the control signal is a pulse width modulated signal to control the output power of the variable power source.

4. The soldering iron system according to claim 1, wherein the set temperature input is adjustable by an operator of the soldering iron system.

5. The soldering iron system according to claim 1, wherein the set temperature input is automatically adjustable by the processor based on one or more of: a cassette type, a horn size, a horn shape, a heat load type or size, and a quality of a weld joint formed by the welding horn and determined by the processor.

6. The soldering iron system according to claim 5, wherein the processor determines the quality of the solder joint by determining a thickness of an intermetallic compound (IMC) of the solder joint and determining whether the thickness of the intermetallic compound (IMC) is within a predetermined range.

7. The soldering iron system according to claim 5, wherein the processor generates an indication signal indicating that a reliable solder joint connection is formed and transmits the indication signal when the thickness of the intermetallic compound (IMC) is within the predetermined range.

8. The soldering iron system according to claim 1, wherein the coil receives a high frequency alternating current to generate electromagnetic induction by eddy currents to heat the soldering tip as an electrically conductive object.

9. The soldering iron system according to claim 1, wherein the soldering cartridge includes a memory that stores unique PID factors to maximize thermal performance.

10. The soldering iron system according to claim 1, wherein the solder cartridge comprises a plurality of solder cartridges, wherein each solder cartridge of the plurality of solder cartridges comprises a memory that stores unique PID factors to maximize thermal performance.

11. The soldering iron system according to claim 10, wherein the soldering iron system uses the temperature sensor to control different temperature set points.