KR20210132384A - Laser reflow device for power semiconductors - Google Patents

Abstract

The present invention relates to a laser reflow device for pressing a plurality of electronic components arranged on a substrate with a light-transmitting pressing member while bonding the electronic components to the substrate by irradiating a laser beam through a pressing member. The light-transmitting pressing member comprises: a material having an overall rectangular panel shape; and a pressing part formed to protrude from the bottom surface of the material to correspond to a plurality of electronic components. The side surface of the pressing part comprises a vertical or inclined shape.

Description

Laser reflow device for power semiconductors

The present invention relates to a laser reflow device, and more particularly, the shape of the material that transmits the Jayr beam, such as quartz, constituting the pressing surface so that a plurality of electronic components can be simultaneously pressed and pressed, the laser beam is incident on. It has a multi-slanted rectangular parallelepiped shape that is wide at the upper part and narrows at the lower part where the laser beam is emitted, and the resulting lower surface is made up of multiple grids arranged apart. It relates to a laser reflow device for power semiconductors that makes it possible. However, applications of these devices can be widely applied not only to power semiconductors, but also to various types of memories, non-memory semiconductors, and electronic components.

In industrial laser processing, an application field with micron (㎛) level precision is micro laser processing, which is widely used in the semiconductor industry, the display industry, the printed circuit board (PCB) industry, and the smartphone industry. Memory chips used in all electronic devices have developed technologies to reduce the circuit spacing to a minimum to realize the degree of integration, performance, and ultra-high-speed communication speed. It has become difficult to stack memory chips in a vertical direction. The stacking technology up to 128 layers has already been developed by TSMC, and the stacking technology up to 72 layers is being applied to mass production by Samsung Electronics and SK Hynix.

In addition, technology development for mounting a memory chip, a microprocessor chip, a graphic processor chip, a wireless processor chip, a sensor processor chip, etc. in one package is intensely researched and developed, and a considerable level of technology is already being applied in practice.

However, in the process of developing the above-mentioned technology, more and more electrons have to participate in the signal processing process inside the ultra-high-speed/ultra-high-capacity semiconductor chip, so the power consumption increases, and the issue of cooling processing for heat has been raised. In addition, in order to achieve the requirements of ultra-high-speed signal processing and ultra-high frequency signal processing for more signals, a technical issue that large amounts of electrical signals must be transmitted at high speed has been raised. In addition, since the number of signal lines has to be increased, it is no longer possible to process the signal interface lines to the outside of the semiconductor chip using a one-dimensional lead wire method, but a ball grid array (BGA) method (Fan-In BGA) that processes two-dimensionally at the bottom of the semiconductor chip. Or Fan-in Wafer-Level-Package (FIWLP)) and a signal layout redistribution layer under the ultra-fine BGA layer under the chip, and a second fine BGA layer is installed under it. The method (referred to as Fan-Out BGA or Fan-Out Wafer-Level-Package (FOWLP) or Fan-Out Panel-Level-Package) is being applied.

Recently, in the case of semiconductor chips, products with a thickness of 200 μm or less including an EMC (Epoxy-Mold Compound) layer have appeared. As such, in order to attach micron-level ultra-thin semiconductor chips with a thickness of only several hundred microns to ultra-thin PCBs, the same mass reflow (SMT) standard process, Thermal Reflow Oven technology, is used. When the MR) process is applied, the semiconductor chip is exposed to an air temperature environment of 100 to 300 degrees (℃) for a period of several hundred seconds. - Various types of soldering bonding defects, such as PCB-Boundary Warpage and Random-Bonding Failure by Thermal Shock, may occur.

In addition, semiconductors used for power control of power systems of electric vehicles and general vehicles, and inverters and converters of battery-based electric drive devices are called power semiconductors or power semiconductors and are widely used. Power semiconductors require high voltage resistance and high reliability compared to general semiconductors, and are core strategic components widely used in mobile phones, laptops, solar power generation, wind power generation, and high-speed trains, in addition to automobiles. In future cars, a lot of electronic parts are attached due to the increase in engine electronic control and various convenience specifications to achieve high fuel efficiency. is becoming In particular, to improve the performance of electric vehicles, high-capacity electric batteries are being installed to increase the mileage per charge (average battery capacity 3-5 years ago: 20-30kW, future: 60-100kW). The demand for power semiconductors for stable operation and high-capacity high-speed control without fire/power failure/high temperature failure due to the installation of high-capacity batteries is rapidly increasing.

As electric vehicles are now sold in millions of units annually, it has already been proven in terms of marketability/technology that they are a key future food source. In electric vehicles, the power semiconductor can be divided into a power control unit and a power module device, which can It drives the motor by converting DC to 3-phase AC while supplying it to the unit. The electric vehicle power module, which is a core component of the battery of electric vehicles, converts AC power to DC (when charging the battery), DC power to AC (when driving a motor), and high-voltage DC to low-voltage DC (when driving automotive electronic products) ), which is a key component of electric vehicles and all electric drives required for conversion. In the case of the power control unit, in order to minimize output loss as well as stable high-speed control, a SiC-based power module that can minimize high-speed control and output loss is applied instead of the existing Si chip-based power module. In the case of SiC-based power modules, miniaturization is possible, so it has advantages in automotive design. Its efficiency is 4-5 times better than Si power semiconductors, so the size can be reduced to 1/5, and carbonization with excellent characteristics such as high frequency operation characteristics Demand for silicon (SiC) power semiconductors has been steadily increasing for the past several years, and explosive growth is expected in the future.

This power semiconductor used silicon (Si)-based semiconductors before the advent of electric vehicles, and has the advantage of using a general lead-free 240 degree bonding process. There were downsides. With the recent advent of electric vehicles, the battery capacity of 60 to 100 kWH, which is much larger than the 3 kWH class of general vehicles, is applied, making it possible to drive up to 300 to 600 km on a single charge. Silicon carbide (SiC)-based power semiconductors are newly developed and used because the previous silicon power semiconductors are not sufficient to control the charging and discharging of these electric vehicle batteries at high speed/high capacity. In addition, during high-speed/high-capacity control, heat is generated and the operating temperature rises to around 300 degrees. Therefore, it is necessary to apply a bonding process of more than 350 degrees by introducing Ag sintering or Cu sintering process. In particular, in the case of SiC/GaN devices that operate at high temperatures, since the chip bonding material operates at high temperatures of 200°C or higher, it is disadvantageous in maintaining bonding characteristics and securing bonding strength with conventional low-melting solder bonding, so silver (Ag), copper Technological development is progressing in the direction of bonding by sintering nano-material metals with high melting points such as (Cu). The sintering bonding technology is a bonding technology that secures high reliability even at a high temperature of 250°C or higher. It is a pressure bonding technology that uses an Al-based/Cu-based sintering paste. In particular, in the case of SiC power semiconductors, it is a bonding that is satisfactory when used at a higher temperature. it's technology During sintering bonding, the remelting temperature after bonding becomes the original melting point of the metal, so it is 961.8°C for Ag-based sintered bonding and 1085°C for Cu-based sintered bonding.

In the case of Ag-based sintered junctions, reliability has been verified and some products have been commercialized as SiC-based power semiconductor junction materials. Cu-based sintered bonding has been suggested as an alternative to Ag-based sintered bonding as it can lower the mass production cost in terms of material cost, but it still has a problem of improving productivity by thermal sintering. When using the same type of Cu heat sink, it is possible to secure a similar level of reliability in adhesive strength and is known to have excellent various electrical properties.

Since the sintering bonding process is a process of pressing fine sub-micron-sized particles and baking them at a high temperature for a certain period of time or more, a pressurization process is absolutely necessary. Therefore, although there are variations, it generally requires a heat press sintering time of 30 to 90 minutes, and the productivity is low. The technology for overcoming this low productivity problem is laser pressure bonding equipment using a laser, and only the chip at the position where the laser beam is irradiated absorbs the laser beam energy, is converted into heat, and is heated to a high temperature for bonding. The power semiconductor is placed on the module substrate Since the distance between chips is larger than the chip size, when pressing a large area at once and irradiating a laser beam, all of the laser power irradiated to the space without chips does not contribute to the bonding process and is wasted energy. In order to overcome this problem, the present patent multiplexes and manufactures a pressing module having a function of pressurizing while passing through a laser beam. The lower surface of the multiplexed pressurization module, which has a size similar to that of The laser beam energy wasted by irradiating it is totally reflected on the inclined surface, gathers at the lower surface to form a uniform mode beam, and heats the chip to efficiently perform the sintering and bonding function.

Accordingly, looking at the configuration of a laser reflow device, which has been in the spotlight recently, a laser head module is bonded by irradiating a laser while pressing an electronic component such as a semiconductor chip or an integrated circuit IC, which is a bonding object, for a few seconds. Alternatively, bonding is performed by irradiating a laser in the form of a surface light source corresponding to the size of the integrated circuit (IC).

For such a pressurized laser head module, referring to Korean Patent Registration No. 0662820 (hereinafter referred to as 'Prior Document 1'), the flip chip is heated by irradiating a laser to the rear surface of the flip chip, while the flip chip is A configuration of a flip-chip hot-pressing module for compressing the substrate to the carrier substrate is disclosed.

However, the conventional pressing type laser head module as described above is separated into a means for adsorbing the chip and moving it to the bonding position, and a means for heating the back surface of the chip through a laser and pressing the chip to the carrier substrate at the same time. Therefore, in the case of bonding a plurality of semiconductor chips such as a semiconductor strip, the operation of irradiating a laser while pressurizing one semiconductor chip must be repeatedly performed as many as the number of the plurality of semiconductor chips, thereby increasing the working time.

On the other hand, referring to Korean Patent Application Laid-Open No. 2017-0077721 (hereinafter referred to as 'Prior Document 2'), the pressure head configuration mentioned in the patent is a state in which the pressure head presses several flip chips at the same time, and the laser head moves in the horizontal direction. It is generally mentioned that the bonding process is possible by irradiating each flip chip sequentially one by one while transporting, or by simultaneously irradiating lasers on several flip chips by a single laser head.

However, according to the conventional pressure head configuration of the above-mentioned Prior Document 2, it is technically difficult to irradiate and reflow a homogenized laser beam by simultaneously irradiating a single laser beam to a plurality of flip chips from various angles using a single laser source. difficulties are expected.

Therefore, if the flip-chip is sequentially processed one by one using a single laser source, the total working time is still inevitably increased, and even when a single laser source is simultaneously irradiated to a plurality of flip-chips, homogenized laser processing may be difficult. .

Accordingly, the present invention was invented to solve the above problems, and the present invention provides a laser reflow device with a significantly improved defect rate while allowing mass processing by irradiating a homogenized laser beam while simultaneously pressing a plurality of electronic components. intended to provide

The present invention is a laser reflow apparatus for bonding electronic components to a substrate by pressing a plurality of electronic components arranged on a substrate with a light-transmitting pressing member and simultaneously irradiating a laser beam through the pressing member, wherein the light-transmitting pressing member comprises: , A substrate having an overall rectangular panel shape; and a pressing part protruding from the bottom surface of the substrate and formed to correspond to a plurality of electronic components, and a side surface of the pressing part has a vertical or inclined shape.

According to the present invention as described above, mass processing is possible by irradiating a homogenized laser beam while simultaneously pressing a plurality of electronic components, thereby greatly improving productivity.

1 is an exemplary view showing the overall configuration of the pressure head of the laser reflow device of the present invention
Figure 2 is a block diagram of Figure 1
3 is a conceptual diagram of a single laser beam module according to an embodiment of the pressing head of the present invention;
4 is a conceptual diagram of a dual laser beam module according to another embodiment of the pressing head of the present invention;
5 is a configuration diagram of a dual laser beam module according to another embodiment of the pressing head of the present invention;
6 to 9 are diagrams of a laser optical system applicable to a dual laser beam module according to another embodiment of the pressing head of the present invention;
10 is a cross-sectional view showing a light-transmitting pressing member of the pressing head of the present invention;
11 is a cross-sectional view of a light-transmitting pressing member including a body portion;
12 is a partial perspective view of a light-transmitting pressing member including a body portion;

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise" or "have" to "include" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the present specification exist, but one It should be understood that it does not preclude the existence or addition of other features or numbers, steps, operations, components, parts, or combinations thereof, or other features or more.

Unless defined otherwise herein, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present specification. shouldn't

Hereinafter, a reflow apparatus according to the present invention will be described in detail with reference to the accompanying FIGS. 1 and 2 .

1 is an exemplary view showing the overall configuration of the pressure head of the laser reflow apparatus of the present invention, FIG. 2 is a block diagram of FIG.

As shown in FIG. 1, the pressure head of the laser reflow apparatus according to the present invention is a porous material having a structure capable of applying heat to the lower portion or a bonding object transferred while being supported by a stage 111 having a vacuum hole formed therein. A pressing unit including a laser irradiation unit 120 that irradiates a laser in the form of a surface light source to 11, and a transmissive pressing member 100 that is installed independently from the laser irradiation unit 120 and transmits a laser in the form of a surface light source is composed

First, the laser irradiator 120 converts the laser generated by the laser oscillator and transmitted through the optical fiber 121 into a surface light source to irradiate the bonding object 11 . The laser irradiation unit 120 includes a beam shaper 122 that converts a spot type laser into a surface light source type, and a surface light source disposed under the beam shaper 122 and emitted from the beam shaper 122 to the bonding object. A plurality of lens modules to be irradiated to the irradiation area of (11) may be implemented including an optical unit 123 that is mounted to be spaced apart from each other at an appropriate distance inside the barrel.

The laser irradiation unit 120 rises or falls along the z-axis or left along the x-axis for alignment with the bonding object 11, for flatness adjustment and height adjustment between the bonding object 11 and the light-transmitting pressing member 100 , can be moved right or along the y-axis.

The pressure head of the laser reflow apparatus according to the present invention includes a light-transmitting pressure member 100 for pressing the bonding object 11 and a laser irradiation unit 120 for irradiating a laser in the form of a surface light source to the bonding object 11 independently of each other. By separating and forming, one bonding object ( 11) shortening of the tact time and speeding up the bonding operation for the plurality of bonding objects as a whole can be realized.

The pressure head of the laser reflow device according to the present invention includes at least one actuator for applying pressure to the light-transmitting pressure member 100 and at least one pressure sensor for sensing the pressure applied to the light-transmitting pressure member 100 and the light-transmitting pressure member. It may be implemented including one or more height sensors for detecting the height. By adjusting the pressure applied to the bonding object through the pressure sensor, in the case of a large area, it is possible to control so that the same pressure is transmitted to the bonding object through a plurality of actuators and a plurality of pressure sensors. Provides technical data to check the height position value at the moment the bonding object is bonded through the sensor or to find a more accurate bonding height value, and controls the correct height when performing a process that requires maintaining a constant height interval perform the functions it can.

The light-transmitting pressing member 100 may be implemented as a base material that transmits the laser output from the laser irradiation unit 120 . The base material of the light-transmitting pressing member 100 can be implemented with any beam-transmitting material. The base material of the light-transmitting pressing member 100 may be implemented with, for example, any one of quartz, sapphire, fused silica glass, or diamond. However, the physical properties of the light-transmitting pressing member made of quartz are different from the physical properties of the light-transmitting pressing member made of sapphire. For example, when irradiating a 980 nm laser, the transmittance of the light-transmitting pressing member made of quartz material is 85% to 99%, and the temperature measured at the bonding object is 100°C. On the other hand, the transmittance of the light-transmitting pressing member made of sapphire is 80% to 90%, and the temperature measured at the bonding object is 60°C.

That is, in terms of light transmittance and heat loss required for bonding, quartz exhibits superior performance than sapphire. However, the inventor of the present application repeatedly tested the light-transmitting pressing member 100 while developing the laser reflow device. As a result, the light-transmitting pressing member 100 made of a quartz material is cracked during laser bonding. It was found that there was a problem in that the bonding quality was poor due to burning or the occurrence of burning on the bottom surface. It was analyzed that the gas (fumes) generated during laser bonding adheres to the bottom surface of the light-transmitting pressing member 100 , and the heat source of the laser is concentrated on the part to which the gas (fumes) is adhered, thereby increasing thermal stress.

In order to prevent damage to the light-transmitting pressing member made of a quartz material and to improve durability, a thin film coating layer may be formed on the bottom surface of the light-transmitting pressure member made of a quartz material. The thin film coating layer formed on the bottom surface of the light-transmitting pressing member may be implemented by a dielectric coating, a SiC coating, or a metallic material coating, which is a conventional optical coating.

The light-transmitting pressing member transfer unit 140 moves the light-transmitting pressing member 100 to a working position or a standby position. For example, the light-transmitting pressure member transfer unit 140 may lower or raise the light-transmitting pressure member 100 , or move it left or right to lower or raise the light-transmitting pressure member 100 .

The light-transmitting pressure member transfer unit 140 may include at least one pressure sensor for detecting the pressure applied to the light-transmitting pressure member 100 and a height sensor for detecting the height of the light-transmitting pressure member. The pressure sensor may be implemented as, for example, at least one load cell. The height sensor may be implemented as a linear encoder.

The pressure head of the laser reflow apparatus according to the present invention is, as shown in FIG. 1 , the light-transmitting pressure member 100 under the light-transmitting pressure member 100 , and gas (fumes) generated during laser bonding is applied to the bottom surface of the light-transmitting pressure member 100 . It may be implemented by further including a protective film transfer unit 210 for transferring the protective film 211 to prevent sticking.

The protective film transfer unit 210 may be implemented in a reel-to-reel manner in which the protective film wound in a roll shape is released and transferred to one side. The protective film 211 is, for example, preferably implemented with a material having excellent heat resistance such that the maximum use temperature is 300 degrees Celsius or more, and the continuous maximum use temperature is 260 degrees or more. For example, the protective film 211 may be implemented with a polytetrafluoroethylene resin (commonly referred to as a Teflon resin; Polytetrafluoroethylene, PTFE) or a purple alkoxy resin. Perfluoroalkoxy resin (Per Fluoro Alkylvinyether copolymer; PFA) is a product that improves the heat resistance of fluorinated ethylene propylene resin.

2, the pressure head of the laser reflow apparatus of the present invention includes a laser irradiation unit 120, a light-transmitting pressure member 100, a light-transmitting pressure member transfer unit 140, a support unit 150, and a protective film transfer unit ( 210) may be implemented.

The laser irradiator 120 converts a spot type laser generated from a laser oscillator and transmitted through an optical fiber 121 into a surface light source type to irradiate the bonding object. The laser irradiation unit 120 includes a beam shaper 122 that converts a spot type laser into a surface light source type, and a surface light source disposed under the beam shaper 122 and emitted from the beam shaper 122 to the bonding object. A plurality of lens modules may be implemented to include an optical unit 123 mounted to be spaced apart from each other inside the barrel so as to be irradiated to the irradiation area of the .

For example, the laser irradiation unit 120 may further include a barrel driving unit for adjusting the range and heating temperature of the irradiation area of the surface light source by individually raising or lowering the plurality of lens modules. According to this embodiment, bonding can be performed by selectively irradiating a laser to the bonding object.

In addition, although not shown in FIG. 2, the pressure head of the present invention includes a control unit for controlling the operation of the light-transmitting pressure member transfer unit 140 using the data input from the pressure sensor and the height sensor. The pressure sensor and the height sensor may be installed on the stage 111 supporting the light-transmitting pressure member 100 and the light-transmitting pressure member transfer unit 140 and the bonding object. For example, the control unit receives data from the pressure sensor and controls the light-transmitting pressing member transfer unit 140 so that the pressure reaches a target value, and also receives data from the height sensor and receives data from the height sensor to reach the target value of the height. can control

The support part 150 supports the light-transmitting pressing member transfer part 140 to be movable. For example, the support 150 may be implemented as a pair of gantry extending in parallel with the stage 111 . However, the support 150 should be interpreted as including a configuration that supports the light-transmitting pressing member transfer unit 140 to be movable in the x-axis, y-axis, or z-axis.

3 is a conceptual diagram of a single laser beam module according to an embodiment of the pressing head of the present invention, and FIG. 4 is a conceptual diagram of a dual laser beam module according to another embodiment of the pressing head of the present invention.

Referring to FIG. 3, the present invention is provided with a single laser module 310 according to an embodiment, thereby irradiating a single laser beam on the FPCB substrate. At this time, referring to FIG. 3 , the laser beam irradiated by the first laser module 310 is irradiated on the substrate in a state in which the intensity of the laser beam is transformed into a homogenized square beam shape.

Meanwhile, referring to FIG. 4 , the dual beam module according to another embodiment of the present invention includes a first laser beam module 210 and a second laser beam module 220, and the By irradiating 1 and 2 laser beams in an overlapping state, a homogenized overlapping laser beam is irradiated.

4 shows that the first laser beam has a square shape and the second laser beam has a circular shape, but both laser beams may have a square shape. Also, the first laser beam and the second laser beam may be simultaneously irradiated, or the second laser beam may be sequentially irradiated after the substrate is preheated by the first laser beam.

5 is a configuration diagram of a dual laser beam module according to another embodiment of the pressing head of the present invention.

In FIG. 5, each laser module (310, 320, ... 330) of the laser irradiation unit has a laser oscillator (311, 321, 331), beam shapers (312, 322) provided with cooling devices (316, 326, 336), respectively. , 332), optical lens modules (313, 323, 333), driving devices (314, 424, 334), control devices (315, 325, 335) and the power supply (317, 327, 337) is configured to include.

Hereinafter, except where necessary, the first laser module 310 among laser modules having the same configuration will be mainly described in order to avoid overlapping description.

The laser oscillator 310 generates a laser beam having a wavelength and output power in a predetermined range. The laser oscillator is, for example, a diode laser (Laser Diode, LD) having a wavelength of '750 nm to 1200 nm' or '1400 nm to 1600 nm' or '1800 nm to 2200 nm' or '2500 nm to 3200 nm' or a rare earth medium fiber laser (Rare-Earth- Doped Fiber Laser) or rare earth medium photonic crystal laser (Rare-Earth-Doped Crystal Laser), alternatively, a medium for emitting alexandrite laser light having a wavelength of 755 nm, or Nd Yag (Nd) having a wavelength of 1064 nm or 1320 nm :YAG) may be implemented including a medium for emitting laser light.

The beam shaper 312 converts a spot type laser generated from a laser oscillator and transmitted through an optical fiber into an area beam type having a flat top. The beam shaper 312 may be implemented by including a square light pipe, a diffractive optical element (DOE), or a micro-lens array (MLA).

The optical lens module 313 adjusts the shape and size of the laser beam converted from the beam shaper to the surface light source shape to irradiate the electronic component mounted on the PCB board or the irradiation area. The optical lens module constitutes an optical system by combining a plurality of lenses, and the detailed configuration of such an optical system will be described later in detail with reference to FIGS. 6 to 9 .

The driving device 314 moves the distance and position of the laser module with respect to the irradiated surface, and the controller 315 controls the driving 314 to form a beam when the laser beam reaches the irradiated surface and the size of the beam area. , adjust the beam sharpness and beam irradiation angle. The control device 315 may also integrally control the operation of each part of the laser module 310 in addition to the driving device 314 .

On the other hand, the laser power adjustment unit 370 is supplied to each laser module from the power supply unit 317, 327, 337 corresponding to each laser module (310, 320, 330) according to a program received through the user interface or a preset program. control the amount of power The laser output adjusting unit 370 receives information about each part, each area, or the entire reflow state on the irradiation surface from one or more camera modules 350 and controls each power supply unit 317 , 327 , 337 based on the received information. On the other hand, the control information from the laser power adjusting unit 370 is transmitted to the control devices 315, 325, 335 of each laser module 310, 320, 330, and in each of the control devices 315, 325, 335, respectively. It is also possible to provide a feedback signal for controlling the corresponding power supply 317 . In addition, unlike FIG. 6 , it is also possible to distribute power to each laser module through one power supply unit. In this case, the laser output adjusting unit 370 needs to control the power supply unit.

When implementing the laser overlap mode, the laser output adjustment unit 370 is configured so that the laser beam from each laser module 310, 320, 33 has a required beam shape, beam area size, beam sharpness and beam irradiation angle to each laser module and Controls the power supply (317, 327, 337). The laser overlap mode uses the first laser module 310 to preheat the area around the debonding target position and uses the second laser module 320 to further heat the narrower reflow target area, as well as the preheating function to It also applies when controlling each laser module to have a required temperature profile by properly distributing the additional heating function between the first, second, and third laser modules 310, 320, ... 330.

Meanwhile, when one laser light source is distributed and input to each laser module, a function for simultaneously adjusting the output and the phase of each distributed laser beam may be provided in the laser power adjusting unit 370 . In this case, the beam flatness can be significantly improved by controlling the phase to induce destructive interference between the respective laser beams, thereby further increasing the energy efficiency.

On the other hand, when implementing a multi-position simultaneous processing mode, the laser power adjusting unit 370 makes a part or all of the laser beams from each laser module different so that the beam shape, beam area size, beam clarity, and beam irradiation of each laser beam are different. Controls one or more of angle and beam wavelength. Even at this time, when one laser light source is distributed and input to each laser module, a function for simultaneously adjusting the output and phase of each distributed laser beam may be provided in the laser power adjusting unit 370 .

Through this function, bonding between the electronic components and the substrate in the irradiation surface can be performed or bonding can be removed by adjusting the laser beam size and output. In particular, when a damaged electronic component is removed from the substrate, the application of heat by the laser beam to other adjacent or normal electronic components existing on the substrate can be minimized by minimizing the area of the laser beam to the corresponding electronic component area. Thereby, it is possible to remove only the damaged electronic component to be removed.

On the other hand, in the case where a plurality of laser modules emit laser beams having different wavelengths, the laser irradiator is capable of absorbing a plurality of material layers (eg, EMC layer, silicon layer, solder layer) included in the electronic component well. It can consist of individual laser modules with wavelengths. Accordingly, the laser debonding apparatus according to the present invention selectively increases the temperature of the electronic component and the temperature of the intermediate bonding material such as solder, which is a connecting material between the printed circuit board or the electrode of the electronic component, to be optimized for bonding (attaching or bonding). Bonding) or separation (Detaching or Debonding) process may be performed. Specifically, it penetrates both the EMC mold layer and the silicon layer of the electronic component so that all energy of each laser beam is absorbed by the solder layer, or the laser beam does not penetrate the EMC mold layer and heats the surface of the electronic component to lower the electronic component It is also possible to conduct heat to the bonding portion of the

On the other hand, by utilizing the above function, a predetermined area of the substrate including the electronic component region to be reflowed and its surroundings is preheated to a predetermined preheating temperature by at least one first laser beam, and then, at least one second laser beam Accordingly, the temperature of the electronic component area to be reflowed is selectively heated up to the reflow temperature at which solder melting occurs.

6 to 9 are diagrams of a laser optical system applicable to a dual laser beam module according to another embodiment of the pressing head of the present invention.

6 is an optical system of the simplest structure applicable to the present invention. When the laser beam emitted from the beam transmission optical fiber 410 is focused through the convex lens 420 and is incident on the beam shaper 430, the beam shaper 430 ), converts a spot-shaped laser beam into a flat-top-shaped surface light source A1, and a square laser beam A1 output from the beam shaper 430 passes through a concave lens 440 to a desired size. It is irradiated to the image-forming surface (S) with the enlarged surface light source (A2).

7 is a configuration diagram of a laser optical system according to another embodiment of the present invention.

The surface light source B1 from the beam shaper 430 is enlarged to a predetermined size through the concave lens 440 to become the surface light source B2 irradiated to the first imaging surface S1. If the surface light source B2 is to be further enlarged and used, the boundary of the edge portion of the surface light source B2 may become more unclear according to the additional enlargement, so that the final irradiation surface is the second imaging surface S2 ), the edge is trimmed by installing a mask 450 on the first imaging surface S1 in order to obtain the irradiated light with a clear edge.

The surface light source passing through the mask 450 is reduced (or enlarged) to a desired size while passing through the zoom lens module 460 composed of a combination of one or more convex and concave lenses, and the second imaging surface on which electronic components are disposed. A rectangular irradiation light B3 is formed in (S2).

8 is a block diagram of a laser optical system according to another embodiment of the present invention.

After the square surface light source C1 from the beam shaper 430 is enlarged to a predetermined size through the concave lens 440, it passes through at least a pair of cylindrical lenses 470 and is enlarged (or reduced) in the x-axis direction, for example. (C2) and again passing through at least a pair of cylindrical lenses 480, for example, is reduced (or enlarged) in the y-axis direction and converted into a rectangular-shaped surface light source C3.

Here, the cylindrical lens is a shape in which a cylindrical shape is cut in the longitudinal direction, and functions to expand or reduce the laser beam according to the shape in which each lens is disposed in the vertical direction, and the lens on the surface on which the cylindrical lens is disposed is x, y The laser beam is adjusted in the x-axis or y-axis direction according to the shape arranged in the axial direction.

Then, the surface light source C3 is enlarged (or reduced) to a desired size while passing through the zoom lens module 460 composed of a combination of one or more convex and concave lenses, and the second imaging surface S2 on which electronic components are disposed. ) to form a rectangular irradiation light C4.

9 is a configuration diagram of a laser optical system according to another embodiment of the present invention.

The optical system of FIG. 9 has a configuration for trimming the edge of the laser beam by applying a mask to the optical system of FIG. 8, and it is understood that the final surface light source D5 having a sharper edge can be obtained compared to the case of FIG. will be able

Fig. 10 is a cross-sectional view showing the light-transmitting pressing member of the pressing head of the present invention, Fig. 11 is a cross-sectional view of the light-transmitting pressing member including the body portion, Fig. 12 is a main perspective view of the light-transmitting pressing member including the body portion, and Fig. 13 is another light-transmitting pressing member It is a nebulous view of

Hereinafter, looking at the structure of the light-transmitting pressing member 100 according to an embodiment of the present invention with reference to FIGS. 10 to 13 , the light-transmitting pressing member 100 of the present invention as shown in FIG. 10 is a rectangular plate-shaped substrate 131 . ) has a structure in which the pressing part 133 of a certain area is formed to protrude. In addition, as shown in FIG. 11 , the body part 135 may be formed to surround the substrate 131 , and the body part 135 may be omitted depending on the design.

On the other hand, the pressing surface 132 is formed on the lower portion of the pressing part 133 to be in direct contact with the electronic component, and the area of the pressing surface 132 is a predetermined area of the electronic component 11 to be laser reflowed at one time. In consideration of the area, it is designed to correspond to the processing area of the electronic component 11 . Here, the electronic component may be a power semiconductor.

Referring to FIG. 11 , the area of the pressing surface 132 is formed to be narrower than that of the substrate 131 , and the circumference of the pressing unit 133 may be formed to be inclined in a tapered shape or formed vertically.

In the structure shown in FIG. 12 , it is necessary to design and process the pressing surface 132 so as to accurately correspond to the occupied area of each electronic component 11 to be subjected to laser reflow processing.

On the other hand, power semiconductor processing may require pressing for a certain period of time due to the nature of the paste. For example, the power semiconductor coated with silver (Ag) or copper (Cu) paste may be irradiated with a laser beam while the pressing surface is pressed, and pressed until the paste is cured. At this time, the pressing time may be varied depending on the type of paste and the output of the laser beam.

13 is a structure similar to that of FIG. 12, but a shape in which the pressing surface is divided into eight. That is, the number of divisions of the pressing surface may be formed differently depending on the design of the corresponding semiconductor.

In addition, the present invention is not limited only by the above-described embodiment, and since it is possible to create the same effect even when changing the detailed configuration or number and arrangement of the device, those of ordinary skill in the art will present the present invention It is specified that various additions, deletions, and modifications are possible within the scope of the technical idea of

100: light-transmitting pressing member 131: base material
132: pressing surface 133: pressing part
135: body part

Claims (4)

A laser reflow apparatus for bonding electronic components to a substrate by pressing a plurality of electronic components arranged on a substrate with a light-transmitting pressing member and simultaneously irradiating a laser beam through the pressing member, the laser reflow apparatus comprising:
The light-transmitting pressing member,
a substrate having an overall rectangular panel shape;
and a pressing part protruding from the bottom surface of the substrate and formed to correspond to a plurality of electronic components;
The side surface of the pressing part is a laser reflow device for a power semiconductor that has a vertical or inclined shape. The method of claim 1,
A laser reflow device for a power semiconductor that is in direct contact with an electronic component by forming a pressing surface under the pressing part. The method of claim 1,
The laser beam is a laser reflow apparatus for a power semiconductor formed by overlapping irradiating at least two or more laser sources. The method of claim 1,
The light-transmitting pressing member is a laser reflow device for a power semiconductor that is pressed for a predetermined time after the laser beam is irradiated.

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