CN116053153A - Die bonder and die bonding method - Google Patents

Die bonder and die bonding method Download PDF

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Publication number
CN116053153A
CN116053153A CN202310019191.5A CN202310019191A CN116053153A CN 116053153 A CN116053153 A CN 116053153A CN 202310019191 A CN202310019191 A CN 202310019191A CN 116053153 A CN116053153 A CN 116053153A
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China
Prior art keywords
wafer
lead frame
die
heating
material taking
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CN202310019191.5A
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Chinese (zh)
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何祥
江智能
黄道平
黎振升
刘少君
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South China University of Technology SCUT
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South China University of Technology SCUT
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Priority to CN202310019191.5A priority Critical patent/CN116053153A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67011—Apparatus for manufacture or treatment
    • H01L21/67144—Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
    • H01L21/60—Attaching or detaching leads or other conductive members, to be used for carrying current to or from the device in operation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67242—Apparatus for monitoring, sorting or marking
    • H01L21/67248—Temperature monitoring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67242—Apparatus for monitoring, sorting or marking
    • H01L21/67253—Process monitoring, e.g. flow or thickness monitoring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/677—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
    • H01L21/67763—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations the wafers being stored in a carrier, involving loading and unloading
    • H01L21/67766—Mechanical parts of transfer devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/687—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches
    • H01L21/68714—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support
    • H01L21/68742—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using mechanical means, e.g. chucks, clamps or pinches the wafers being placed on a susceptor, stage or support characterised by a lifting arrangement, e.g. lift pins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
    • H01L21/60—Attaching or detaching leads or other conductive members, to be used for carrying current to or from the device in operation
    • H01L2021/60277—Attaching or detaching leads or other conductive members, to be used for carrying current to or from the device in operation involving the use of conductive adhesives
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Robotics (AREA)
  • Die Bonding (AREA)

Abstract

The invention discloses a die bonder and a die bonding method, wherein the die bonder comprises a bearing mechanism, a camera identification mechanism, a heating carrier mechanism, a die taking and bonding mechanism and a wafer table mechanism; the bearing mechanism comprises a lead frame and a frame driving device, wherein the lead frame is provided with a die fixing position for bearing chips, and the frame driving device is responsible for driving the lead frame to move on the carrier track; the camera recognition mechanism is used for realizing photographing and positioning of the bonding pad and recognizing the wafer on the wafer table, so that the lossless wafer is attached to the correct position in the bonding pad; the heating carrier mechanism comprises a carrying track, a carrier heating device and a nitrogen supply mechanism for heating the lead frame, wherein the nitrogen supply mechanism is used for preventing the lead frame from oxidizing, the crystal taking and fixing mechanism comprises a suction nozzle welding head in the xyz direction, and the suction nozzle is fixed at the tail end of the welding head. The wafer table mechanism comprises a wafer table driving motor and a thimble device in the xy direction.

Description

Die bonder and die bonding method
Technical Field
The invention relates to the technical field of die bonding equipment, in particular to a die bonder and a die bonding method.
Technical Field
The semiconductor industry in China is rapidly developing, and the packaging technology is an important link affecting the development of the semiconductor industry. The advantages and disadvantages of the packaging technology of the semiconductor are critical competitive factors, and compared with most semiconductor mechanical equipment in the market, the die bonder has obvious advantages of die bonding precision, speed, stability and the like.
The existing fixing mode is mainly to quantitatively fix silver paste glue to a die bonding position point on a lead frame through a glue dispenser by a physical layer dispensing technology, and then attach a taken-out wafer on the glue to complete connection of components, however, the glue dispensing process is a key factor influencing the final effect, and some process defects are very easy to generate in the production: the glue points are unqualified in size, wire drawing, pad dyeing by glue, poor in curing strength, easy in chip falling and the like;
in the conventional die bonder die bonding process, chips on a wafer are generally fixed at die bonding positions (CN 202210772025.8) on a substrate or a lead frame through a rocker arm and a suction nozzle, firstly, the rocker arm drives the suction nozzle to move downwards to suck the chips on the wafer, then, the rocker arm swings and drives the suction nozzle to rotate (the rocker arm swings to drive the suction nozzle to rotate and simultaneously, the suction nozzle also makes ascending motion), the chips are sent to the upper part of the lead frame, and then, the rocker arm drives the suction nozzle to move downwards to fix the chips on the lead frame; generally, the time of swinging the rocker arm once is within 150ms250ms, and when the chip is sucked or fixed on the lead frame, the suction nozzle needs to stop for tens of milliseconds or even tens of milliseconds, so that the time of swinging the rocker arm back and forth can be prolonged, and each time a chip is fixed, the suction nozzle needs to go through once stopping, sucking the chip and once stopping to fix the chip on the lead frame, thus affecting the die bonding efficiency, and the chip cannot be well attached to the lead frame, and the die bonding quality cannot be guaranteed.
Disclosure of Invention
The invention provides a method for bonding wafers by heating the lead frames, which enables materials at the contact part of chips and the lead frames to be fully diffused and melted, and is provided with a nitrogen supply mechanism to prevent oxidization.
The invention is realized at least by one of the following technical schemes.
A die bonder comprises a bearing mechanism, a heating carrier mechanism, a camera identification mechanism, a die-taking die-bonding mechanism and a die-table mechanism;
the heating carrier mechanism comprises a carrier heating device, a nitrogen supply mechanism and a material taking device;
the mounting mechanism comprises a frame driving device and a lead frame, and a die bonding position for mounting the chip is arranged on the lead frame; the frame driving device drives the lead frame to slide on the carrier heating device, so that the carrier heating device heats the lead frame and then moves the die bonding position of the lead frame to the lower part of the welding head of the die bonding mechanism;
the crystal taking and fixing mechanism comprises a welding head and a servo motor, one end of the welding head is connected with the servo motor, the free end of the other end of the welding head is provided with a replaceable suction nozzle, and the servo motor controls the free end of the welding head to move in the x, y and z directions;
the wafer platform mechanism comprises a wafer platform and a thimble device, the thimble device ejects the wafer from the wafer platform, the wafer is taken out by the welding head suction nozzle, and the wafer is attached to the lead frame for fixing the wafer, so that the wafer reciprocates.
Further, the lead frame is provided with n rows of m columns of die-bonding sites, the n rows of die-bonding sites are arranged along the x direction, the m columns of die-bonding sites are arranged along the y direction, wherein m is more than or equal to 1, n is more than or equal to 1, and n and m are natural numbers.
Further, the frame driving device comprises a screw motor and a pusher dog connected with the screw motor; the carrying platform heating device is carved with a carrying track, and the pusher dog drives the lead frame to move on the carrying track.
Further, the carrier heating device comprises a heating carrier, and a heating cover plate is covered on the heating carrier to prevent heat dissipation; a carrying track for the lead frame to move is engraved on the heating carrier, and a gap for the lead frame to move is reserved between the heating carrier and the heating cover plate;
further, the nitrogen supply mechanism comprises a plurality of temperature sensors, a plurality of nitrogen output pipes and a plurality of heating wires;
the temperature probe of the temperature sensor is connected with the heating carrier and the nitrogen output pipe, the nitrogen output pipe is provided with a nitrogen output port, and the heating wires are wound on the nitrogen output pipe in one-to-one correspondence.
Further, the material taking device comprises a material taking box, a material taking device and a metal sensor, wherein the free end of the material taking device is used for taking materials from the material taking box, the metal sensor is positioned at the bottom of the material taking device, one end of the metal sensor is connected with the air cylinder, and the metal sensor is used for judging whether the taken materials are lead frames or not; the material taking device is positioned right above the material taking box when being initialized, the material taking device is parallel to the material taking box, and the material taking device moves downwards to absorb the lead frames in the material taking box and is placed on the heating carrier mechanism.
Further, the camera recognition mechanism comprises two cameras and is used for shooting images of a wafer table during wafer capturing and a lead frame wafer fixing position during wafer fixing.
Further, the wafer table comprises a wafer disc, and a blue film of the wafer is attached to the wafer disc; the wafer table is connected with the servo motor and the rotating motor, and controls the wafer table to move in the x direction and the y direction and controls the wafer disc to rotate.
Further, the ejector pin device comprises an ejector pin connected with a motor, the motor drives the ejector pin to move in the vertical direction, the wafer is ejected out of the blue film, and the ejector pin device is matched with a welding head suction nozzle to finish synchronous lifting operation to take out the wafer.
The die bonding method for realizing the die bonder comprises the following steps:
s1, dividing a heating carrier into n temperature areas, and heating in real time according to a set temperature;
s2, when the temperatures of the n temperature areas are heated to the specified temperature, a material taking device of the material taking device takes out a lead frame from a material box, a sensor at the bottom of the material taking device is in contact with the lead frame, whether the material is a metal lead frame is judged according to signals of the sensor, if so, a cylinder connected with the sensor is triggered to be opened, the material taking device absorbs the lead frame and is placed at the starting end of a heating carrier, if not, the cylinder connected with the sensor is closed, the material taking device discards the material taken out, and the material is taken out from the material taking box again;
s3, placing the pusher dog into an edge small hole of the lead frame, driving the lead frame to slowly move in the x direction on a carrying track of the heating carrier mechanism, and heating the lead frame by the heating carrier after the lead frame is positioned;
s4, until the first column of the lead frame reaches the position below the welding head, namely the welding lug position, the camera shoots and identifies the welding disc, the shot image is sent to the computer through the image acquisition card, and the computer calculates and converts the die-fixing position coordinates of the lead frame on the image into coordinates which are required to be reached by the welding head, namely die-fixing coordinates;
s5, the other camera shoots and identifies the wafer meeting the specification against the wafer table, an image of the wafer is obtained, the image is sent to a computer through an image acquisition card to be calculated, so that the image coordinate of the wafer is obtained, and software converts the obtained image coordinate of the wafer into a mechanical coordinate corresponding to a welding head, namely a wafer taking coordinate; then the wafer table moves a wafer distance in the x direction under the action of a motor connected with the bottom, and waits for the next identification;
s6, the welding head reaches the position of a crystal taking coordinate, meanwhile, the ejector pin ejects the wafer on the blue film to the vertical direction under the driving action of the motor, the suction nozzle of the welding head sucks the wafer, the welding head brings the wafer to the crystal fixing coordinate, vertically contacts the crystal fixing position of the lead frame downwards, and places the wafer on the crystal fixing position, so that the chip attaching action of a wafer is completed;
s7, repeating the step s5 and the step s6, moving the pusher dog by a unit distance after all n pieces of the first row of lead frames are welded, repeating the step s4, the step s5 and the step s6 again until all die fixing positions of one lead frame are provided with chips, conveying the finished lead frames to a discharging area through the pusher dog, and placing the lead frames into a discharging box;
s8, repeating the steps s 2-s 7 until all the lead frames in the material taking box are taken out.
Compared with the prior art, the beneficial effects of the method are as follows:
in the die bonder, the z-axis of the welding head drives the suction nozzle to move, chips are taken out of a wafer through the cooperation of the ejector pins from the wafer disk, and the chips are conveyed to a die bonding position on a lead frame. The die bonding positions on the lead frame are generally distributed in a matrix, the suction nozzles are used for carrying out soldering lugs in a row, after the row is finished, the lead frame is driven by the pusher dog to move forwards by a unit to carry out the soldering lugs in the next row, therefore, the bonding head mainly moves in the y direction and the z direction, the wafer disc seat is provided with the ejector pins, when the bonding head suction nozzle reaches the upper side of a wafer, the bonding head and the ejector pins are lifted at the same time, the bonding head is not contacted with the wafer, the synchronous lifting action is mainly used for preventing the wafer from being damaged, the die bonding quality is greatly improved, the movement of the bonding head is carried out in the y direction and the z direction in a reciprocating mode, a traditional swing arm is not needed, and the suction nozzle is responsible for matching the ejector pins to absorb the ejected wafer and attach the wafer to a lead frame bonding pad heated at high temperature, so that the die bonding time is saved, and the die bonding efficiency is improved.
The die bonding method of the invention is applied to the die bonding machine, and can provide an oxygen-free environment by the nitrogen supply mechanism when die bonding is carried out, so that the chip or the lead frame is prevented from being oxidized due to contact with air when being heated; and the temperature of the nitrogen is close to that of the die bonder, the nitrogen can not exchange excessive heat with the chip, so that the temperature of the chip is more moderate, and the die bonder is not influenced by the accident of die bonding caused by excessive temperature difference.
Drawings
FIG. 1 is a schematic diagram of a die bonder in a die bonding portion of an embodiment of the present application;
FIG. 2 is a schematic structural diagram of a die bonding portion according to another embodiment of the present disclosure;
fig. 3 is a schematic view of a leadframe structure of the die bonder shown in fig. 1;
FIG. 4 is a schematic view of a part of a bonding tool of the die bonder shown in FIG. 1;
FIG. 5 is a front view of a wafer table structure according to an embodiment of the present application;
FIG. 6 is a schematic view of a wafer table according to an embodiment of the present application;
FIG. 7 is a schematic view of a thimble structure according to an embodiment of the present disclosure;
FIG. 8 is an exploded view of an ejector pin structure according to an embodiment of the present application.
Reference numerals illustrate:
11-lead frame, 12-die attach; 2-crystal taking and fixing mechanism: 21-a rotating electric machine; 22-welding heads, 23-welding head displacement sensors, 24-force control motors and 25-suction nozzles; 3-heating stage mechanism: 31-heating wires, 32-nitrogen output pipes, 33-cover plates, 34-carrying rails and 35-heating carriers; 4-wafer table mechanism: 41-wafer discs, 42-x-axis moving platforms, 43-y-axis moving platforms and 44-wafer rotating motors; 5-thimble device: 51-motor, 52-thimble cap, 53-thimble, 54-base and 55-ejector rod; 100-X direction, 200-Y direction, 300-Z direction.
Detailed Description
For the purpose of making the technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, and the described embodiments are only some embodiments of the present invention, but not all examples. Based on the examples herein, other embodiments are within the scope of the present invention as would be appreciated by one of ordinary skill in the art without undue burden.
As shown in fig. 1 to 8, a die bonder of the present embodiment includes a carrying mechanism, a die-picking and die-bonding mechanism 2, a heating stage mechanism 3, a wafer stage mechanism 4, and a camera recognition mechanism 5;
the bearing mechanism comprises a frame driving device and a lead frame 11, wherein the lead frame 11 comprises a die bonding position 12, and the die bonding position 12 is also called a bonding pad;
the frame driving device comprises a screw motor and a pusher dog connected with the screw motor, and the pusher dog drives the lead frame to move on a carrying track of the heating carrier mechanism. The frame driving device drives the lead frame 11 to slide on the carrying track 34 of the heating carrier 35;
the lead frame 11 is provided with n rows of m rows of die-bonding sites, the n rows of die-bonding sites are arranged along the x direction, and the m rows of die-bonding sites are arranged along the y direction, wherein m is more than or equal to 1, n is more than or equal to 1, and n and m are natural numbers.
The heating carrier mechanism comprises a carrier heating device, a nitrogen supply mechanism and a material taking device;
the carrier heating device comprises a heating carrier 35, wherein a heating cover plate 33 is covered on the heating carrier to prevent heat dissipation; a groove is engraved on the heating carrier 35 to form a carrying track 34 for moving the lead frame 11, and a gap for the lead frame to move is reserved between the heating carrier 35 and the heating cover plate 33;
the carrier heating device comprises a plurality of temperature sensors and heating wires 31, a cover plate 33 and a plurality of nitrogen output pipes 32, wherein a plurality of nitrogen output ports are formed in the nitrogen output pipes, the temperature sensors are provided with a plurality of temperature probes, the probes are connected to a heating carrier 35 and the nitrogen output pipes 32, the heating wires 31 are wound on the nitrogen output pipes 32, the heating carrier mechanism 3 heats a carrying track 34, the cover plate 33 prevents heat dissipation, the carrying track 34 carries a lead frame 11, the lead frame 11 is indirectly heated, the heating wires 31 heat the nitrogen output pipes 32, the temperature difference between the nitrogen ground temperature and the lead frame 11 is not large, too much heat exchange does not exist, the chip temperature reduction is milder, and accidents such as crystal explosion and the like of the chip on the die fixing position 12 are prevented.
The material taking device comprises a material taking box, a material taking device and a metal sensor, wherein the free end of the material taking device is used for taking materials from the material taking box, the metal sensor is located at the bottom of the material taking device, one end of the metal sensor is connected with an air cylinder, the metal sensor is used for judging whether the taken materials are lead frames, the metal sensor is located right above the material taking box when the material taking device is initialized, the material taking device is parallel to the material taking box, and the material taking device can vertically downwards take materials from the material taking box.
The die-picking and die-fixing mechanism 2 comprises a rotating motor 21, a welding head 22 and a welding head displacement sensor 23 which is vertically and parallelly arranged with the welding head, wherein the welding head displacement sensor 23 is mainly responsible for judging whether the welding head contacts with the die-fixing position 12 on the lead frame 11; the welding head 22 is connected with the force control motor 24, the welding head 22 is provided with a replaceable suction nozzle 25, the suction nozzle 25 is fixed at the tail end of the welding head 22 and can be replaced according to the use abrasion condition, and the welding head 22 moves in the Z direction 300 under the driving of the force control motor 24. The rotating motor 21 is connected to a connecting rod of the welding head and controls the rotation of the welding head;
the wafer table mechanism 4 comprises a wafer table, an x-axis moving platform 42, a y-axis moving platform 43, a thimble device 5 and a rotating motor 44; the wafer table comprises a wafer disc 41, and a blue film of the wafer is attached to the wafer disc 41; the thimble device 5 is connected with a servo motor, and the bottom of the wafer table is connected with a rotating motor 44 to drive the wafer disc 41 to rotate to a correct angle; an x-axis motion stage 42 and a y-axis motion stage 43 are mounted at the bottom of the wafer table in a vertical orientation to control movement of the wafer table in the x, y directions.
The ejector pin device 5 comprises an ejector pin 55 and a base 54, wherein the ejector pin 55 is fixed on the base 54, the ejector pin 53 is connected with the motor 51, the motor 51 drives the ejector pin 55 to drive the ejector pin 53 to move in the vertical direction, the wafer is ejected out of the blue film, and the wafer is lifted up synchronously by matching with a welding head suction nozzle.
The fingers of the frame driving device fix the positioning holes hooked on the edge of the lead frame 11, the fingers drive the lead frame 11 to move along the X direction (first direction) and move relative to the heating carrier 35, the lead frame reaches the lower part of the welding head under the action of the fingers, after the die bonding action of the welding head until all the dies on one row of die bonding positions of the lead frame are provided, the fingers drive the lead frame 11 to rapidly move by a unit distance (the distance between two adjacent rows of die bonding positions is called the unit distance) to the next row under the action of the lead screw motor, and the cycle is performed so that the die bonding operation is orderly.
The die bonding sites 12 on the lead frame 11 are distributed in a matrix, a chip is placed on one die bonding site 12 of a row of die bonding sites 12, and the next die bonding site of the bonding tool 22 needs to be added with a die bonding site distance in the Y direction (second direction) 200 so as to place the chip on the next die bonding site of the row; at the same time, the X-moving platform 42 on the wafer table mechanism 4 also needs to move a distance of one wafer, and if the limit of the wafer table mechanism 4 in the X direction (the first direction) 100 exceeds the limit, the y-axis moving platform 43 needs to move a distance of one wafer, so as to perform the z-type wafer taking path. The wafer is not stopped until it is completely removed from the wafer disk or until all of the die 12 on the lead frame 11 are on die.
The finger drive may move along the first direction with the lead frame 11 to correct for errors in the pulling of the lead frame 11, compensating for distance adjustment in the first direction.
Based on the above technical scheme, the bonding tool 22 drives the suction nozzle 25 to move in the X direction (first direction) and the Z direction, the chip is sucked from the wafer, the motor 51 drives the ejector rod 55 to drive the ejector pin 53 to move in the Z direction 300, the ejector pin 53 and the suction nozzle 25 are lifted synchronously to suck the wafer, the chip is moved in the X direction (first direction) 200 and the Z direction 300, the chip is conveyed to the die holder 12 of the lead frame 11, the lead frame 11 is fully heated on the heating carrier 35, the bonding tool 22 pastes the chip on the die holder 12, the chip and the die holder are fully contacted, the solder paste of the die holder is fully covered, and the contact surface is fully melted, so that the crystalline solid quantity is ensured. The lead frame 11 is a metal lead frame.
The die-bonding sites 12 on the lead frame 11 are generally distributed in a matrix, and the height of each row of die-bonding sites 12 is kept the same after the pressure of the cover plate 33, so that the bonding head selects the first column for each row of bonding pads before the machine operates to perform high processing to obtain the height of each row, and then the die-bonding sites 12 of each row are subjected to surface mounting according to the parameters after the high processing, and the surface mounting is performed after the height of each die-bonding site 12 is calculated every time when the surface mounting is performed, thereby saving the time, improving the die-bonding efficiency bar, and ensuring the die-bonding quality.
As a preferred embodiment, the time of one movement of the welding head 22 is within 120ms, since the welding head 22 is not stopped and the time of synchronous lifting of the welding head 22 and the thimble 53 is negligible, the time of one back and forth movement of the welding head 22 will not exceed 240ms, and assuming 15k chips on a wafer, the time of operation of the welding head 22 is 240ms multiplied by 15k, which is 3600s, for about one hour; for the existing die bonder, generally, 15k chips are fixed for more than 90 minutes, so that the die bonder has extremely high die bonding efficiency;
in this embodiment, the sensor of the material taking device is connected with the pusher, the material taking device can trigger the pusher to act when the material is taken, the motor for controlling the wafer table and the motor for controlling the welding head to act can be controlled by the application program to work cooperatively, the application program is inconvenient to describe, but the application program sets the procedure, and the motor connected with the welding head and the motor connected with the wafer table are correspondingly controlled; the feeder sensor is connected with the pusher dog, so that a position sensor for arranging the pusher dog can be omitted, the cost can be saved, and the hardware wiring condition can be reduced.
In this embodiment, the material taking driving, the crystal taking driving, the pusher dog driving, and the wafer table driving may be linear motors, servo motors, stepper motors, air cylinders, or other structures capable of performing linear driving, and the crystal taking driving and the frame driving are performed in a driving manner common in the prior art, which is not described here.
In this embodiment, the second direction 200 is perpendicular to the first direction 100, the third direction 300 is perpendicular to both the first direction 100 and the second direction 200, the upper surface of the lead frame 11 is recessed inward to form the die-bonding sites 12, N rows of M die-bonding sites 12 are arranged on the lead frame 11, N rows of die-bonding sites 12 are arranged along the first direction 100, M rows of die-bonding sites 12 are arranged along the second direction 200, wherein N is greater than or equal to 1, M and N are natural numbers, the bonding tool fixes a row of N die-bonding sites 12 along the second direction, and then moves a die-bonding site unit to complete the die-bonding of all M rows of die-bonding sites 12.
Generally, during die bonding, in order to ensure that the chip can be well attached to the solder paste on the die bonding site 12, the die bonding effect is ensured, the temperature of the chip is typically one hundred degrees celsius to several hundred degrees celsius, so that the solder paste is melted, and the lead frame 11 is typically copper or copper alloy.
In this embodiment, a plurality of nitrogen output ports are distributed on the heating stage 35 at intervals along the first direction 100, and the nitrogen output ports can output nitrogen to push away the air of the heating stage 35, so as to provide an oxygen-free environment for the lead frames 11 on the carrying rails 34, and prevent the chips and the lead frames 11 from being oxidized due to contact with oxygen.
As a preferred embodiment, the preheating temperature of the frame stage 35 is about 450 ℃, and the optimum temperature at the time of die bonding on the lead frame 11 is 480 ℃, so that the temperature of nitrogen gas is also maintained at 480 ℃ of 450 ℃; in addition, the temperature of the carrier 35 is decreased from 340 ℃ to 450 ℃ to 280 ℃ in the first direction 100, so that excessive heat exchange between nitrogen and the chip is prevented, and in practice, the temperature difference between the nitrogen and the chip in die bonding is within 30 ℃, so that the chip can be well cooled.
The heating wires 31 are distributed along the first direction, so that the lead frame 11 is uniformly heated on the carrying track 34, and the temperatures of all the parts are not greatly different.
The camera identification mechanism comprises two CCD industrial cameras, a light source and an image acquisition card, and is used for shooting images of two parts of crystal shooting and crystal fixing; taking out wafers meeting the standard from the wafer disc through a chip identification positioning algorithm based on gray information, a normalization cross-correlation algorithm and the like; and identifying the die bonding position on the lead frame through a template matching algorithm, and fixing the wafer at the accurate position of the die bonding position.
The camera recognition mechanism of the embodiment is divided into a crystal taking camera and a crystal fixing camera, the crystal taking camera mainly takes a picture of a wafer and converts the acquired image coordinates into mechanical coordinates of a welding head, the welding head can take the wafer at an accurate position, and the provided coordinates are the basis for taking the wafer; the die bonding camera is used for obtaining the accurate bonding pad position by photographing the die bonding position 12, and the welding head accurately sticks the chip to the correct position of the die bonding position 12 according to the mechanical coordinates given by the camera conversion, so that the basis is provided for the die bonding position of the bonding pad;
the application also provides a die bonding method, which comprises the following steps:
s1, heating a carrying platform 35, heating n temperature areas of the carrying platform 35 according to a set temperature, acquiring the actual temperature of the carrying platform 35 through a sensor, starting a nitrogen supply mechanism, and outputting nitrogen by a nitrogen output pipe 32;
s2, when the temperature of the n temperature areas is heated to a specified temperature, a material taking device of the material taking device takes out a lead frame from a material box, a sensor at the bottom of the material taking device is in contact with the lead frame, whether the lead frame is a metal lead frame is judged according to signals of the sensor, if so, a cylinder connected with the sensor is triggered to be opened, the material taking device absorbs the lead frame and is placed at the starting end of a heating carrier, if not, the cylinder connected with the sensor is closed, the material taking device discards the material taken out, and the material is taken out from the material taking box again until the lead frame is taken out;
s3, positioning the lead frame 11 by a pusher dog of the frame driving device, putting the pusher dog into an edge small hole of the lead frame 11, carrying out slow movement of the lead frame 11 on a frame carrying platform in a first direction 100, and heating the lead frame 11 by a heating carrying platform 35;
s4, pulling the lead frame by the pusher dog to move on the heating carrier 35 until the first column of the lead frame 11 reaches the position below the welding head, namely the welding lug position, taking a picture by the camera to identify the welding disc, transmitting the taken picture to the computer through the image acquisition card, calculating the die-fixing position coordinates of the lead frame on the picture and converting the die-fixing position coordinates into coordinates which are required to be reached by the welding head, namely die-fixing coordinates;
s5, the other camera shoots and identifies the wafer meeting the specification against the wafer table, an image of the wafer is obtained, the image is transmitted to a computer through an image acquisition card to be calculated, so that the image coordinate of the wafer is obtained, and the software converts the obtained image coordinate of the wafer into a mechanical coordinate corresponding to the welding head, namely the wafer taking coordinate; then the wafer table moves a wafer distance in the first direction 100 under the action of a motor connected with the bottom, and waits for the next recognition;
s6, when the welding head 22 reaches the crystal taking coordinate position, the welding head 22 vertically moves downwards along a third direction 300, at the moment, under the action of a motor 51 pushing a push rod 55, a crystal round platform ejector pin 53 upwards punctures a blue film covered on a crystal round disc 41 along the third direction 300, the crystal round is lifted, a suction nozzle 25 synchronously lifts upwards above the ejector pin 53 until a chip is sucked, then a crystal fixing coordinate welding sheet is removed, the welding head 22 simultaneously moves in a second direction 200 and the third direction 300 under the action of the motor, returns to a crystal fixing coordinate position patch, vertically contacts a crystal fixing position 12 of a lead frame 11 downwards until the chip is arranged on the crystal fixing position 12;
s7, repeating s5 and s6 until all n pieces of the first row of the lead frames 11 are welded, then moving a unit distance by a pusher dog, repeating the steps s4, s5 and s6 again until all die fixing positions 12 of one lead frame 11 are provided with chips, conveying the completed lead frame 11 to a discharging area through the pusher dog, and placing the lead frame 11 into a discharging box;
s8, repeating the steps s 2-s 7 until all the lead frames in the material taking box are taken out.
Further, the temperature of the stage 35 is gradually increased and then gradually decreased along 8 temperature areas arranged in the x direction; generally, the preheating temperature of the frame stage 35 is about 450 ℃, and the optimum temperature at the time of die bonding on the lead frame 11 is 480 ℃, so the temperature of nitrogen gas is also maintained at 480 ℃ of 450 ℃; in addition, the temperature of the carrier 35 is decreased from 340 ℃ to 450 ℃ to 280 ℃ in the first direction 100, so that excessive heat exchange between nitrogen and the chip is prevented, and in practice, the temperature difference between the nitrogen and the chip in die bonding is within 30 ℃, so that the chip can be well cooled.

Claims (10)

1. The die bonder is characterized by comprising a bearing mechanism, a heating carrier mechanism, a camera identification mechanism, a die-picking and die-bonding mechanism and a die-wafer table mechanism;
the heating carrier mechanism comprises a carrier heating device, a nitrogen supply mechanism and a material taking device;
the mounting mechanism comprises a frame driving device and a lead frame, and a die bonding position for mounting the chip is arranged on the lead frame; the frame driving device drives the lead frame to slide on the carrier heating device, so that the carrier heating device heats the lead frame and then moves the die bonding position of the lead frame to the lower part of the welding head of the die bonding mechanism;
the crystal taking and fixing mechanism comprises a welding head and a servo motor, one end of the welding head is connected with the servo motor, the free end of the other end of the welding head is provided with a replaceable suction nozzle, and the servo motor controls the free end of the welding head to move in the x, y and z directions;
the wafer platform mechanism comprises a wafer platform and a thimble device, the thimble device ejects the wafer from the wafer platform, the wafer is taken out by the welding head suction nozzle, and the wafer is attached to the lead frame for fixing the wafer, so that the wafer reciprocates.
2. The die bonder of claim 1, wherein the leadframe is provided with n rows of m rows of die bonding sites, the n rows of die bonding sites being arranged in the x-direction and the m rows of die bonding sites being arranged in the y-direction, wherein m is greater than or equal to 1, n is greater than or equal to 1, and n and m are both natural numbers.
3. The die bonder as claimed in claim 1, wherein the frame driving means includes a screw motor and a finger connected to the screw motor; the carrying platform heating device is carved with a carrying track, and the pusher dog drives the lead frame to move on the carrying track.
4. The die bonder as claimed in claim 1, wherein the stage heating means includes a heating stage covered with a heating cover plate to prevent heat dissipation; the heating carrier is engraved with a carrying track for the lead frame to move, and a gap for the lead frame to move is reserved between the heating carrier and the heating cover plate.
5. The die bonder of claim 4, wherein the nitrogen supply mechanism comprises a plurality of temperature sensors, a plurality of nitrogen output pipes and a plurality of heating wires;
the temperature probe of the temperature sensor is connected with the heating carrier and the nitrogen output pipe, the nitrogen output pipe is provided with a nitrogen output port, and the heating wires are wound on the nitrogen output pipe in one-to-one correspondence.
6. The die bonder of claim 1, wherein the material taking device comprises a material taking box, a material taking device and a metal sensor, wherein the free end of the material taking device is used for taking materials from the material taking box, the metal sensor is positioned at the bottom of the material taking device, one end of the metal sensor is connected with the air cylinder, and the metal sensor is used for judging whether the taken materials are lead frames or not; the material taking device is positioned right above the material taking box when being initialized, the material taking device is parallel to the material taking box, and the material taking device moves downwards to absorb the lead frames in the material taking box and is placed on the heating carrier mechanism.
7. The die bonder of claim 1, wherein said camera recognition mechanism includes two cameras for capturing images of both the die attach table and die attach leadframe die attach sites.
8. The die bonder of any one of claims 1 to 7, wherein the wafer table comprises a wafer disc on which a blue film of a wafer is attached; the wafer table is connected with the servo motor and the rotating motor, and controls the wafer table to move in the x direction and the y direction and controls the wafer disc to rotate.
9. The die bonder as claimed in claim 8, wherein the ejector pin assembly includes ejector pins coupled to the motor, the motor driving the ejector pins to move in a vertical direction to eject the wafer from the blue film, and the ejector pins cooperate with the bonding tool suction nozzle to perform a simultaneous lifting operation to remove the wafer.
10. The die bonding method for realizing the die bonder of claim 9, comprising the following steps:
s1, dividing a heating carrier into n temperature areas, and heating in real time according to a set temperature;
s2, when the temperatures of the n temperature areas are heated to the specified temperature, a material taking device of the material taking device takes out a lead frame from a material box, a sensor at the bottom of the material taking device is in contact with the lead frame, whether the material is a metal lead frame is judged according to signals of the sensor, if so, a cylinder connected with the sensor is triggered to be opened, the material taking device absorbs the lead frame and is placed at the starting end of a heating carrier, if not, the cylinder connected with the sensor is closed, the material taking device discards the material taken out, and the material is taken out from the material taking box again;
s3, placing the pusher dog into an edge small hole of the lead frame, driving the lead frame to slowly move in the x direction on a carrying track of the heating carrier mechanism, and heating the lead frame by the heating carrier after the lead frame is positioned;
s4, until the first column of the lead frame reaches the position below the welding head, namely the welding lug position, the camera shoots and identifies the welding disc, the shot image is sent to the computer through the image acquisition card, and the computer calculates and converts the die-fixing position coordinates of the lead frame on the image into coordinates which are required to be reached by the welding head, namely die-fixing coordinates;
s5, the other camera shoots and identifies the wafer meeting the specification against the wafer table, an image of the wafer is obtained, the image is sent to a computer through an image acquisition card to be calculated, so that the image coordinate of the wafer is obtained, and software converts the obtained image coordinate of the wafer into a mechanical coordinate corresponding to a welding head, namely a wafer taking coordinate; then the wafer table moves a wafer distance in the x direction under the action of a motor connected with the bottom, and waits for the next identification;
s6, the welding head reaches the position of a crystal taking coordinate, meanwhile, the ejector pin ejects the wafer on the blue film to the vertical direction under the driving action of the motor, the suction nozzle of the welding head sucks the wafer, the welding head brings the wafer to the crystal fixing coordinate, vertically contacts the crystal fixing position of the lead frame downwards, and places the wafer on the crystal fixing position, so that the chip attaching action of a wafer is completed;
s7, repeating the step s5 and the step s6, moving the pusher dog by a unit distance after all n pieces of the first row of lead frames are welded, repeating the step s4, the step s5 and the step s6 again until all die fixing positions of one lead frame are provided with chips, conveying the finished lead frames to a discharging area through the pusher dog, and placing the lead frames into a discharging box;
s8, repeating the steps s2 to s7 until all the lead frames in the material taking box are taken out.
CN202310019191.5A 2023-01-06 2023-01-06 Die bonder and die bonding method Pending CN116053153A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310019191.5A CN116053153A (en) 2023-01-06 2023-01-06 Die bonder and die bonding method

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Application Number Priority Date Filing Date Title
CN202310019191.5A CN116053153A (en) 2023-01-06 2023-01-06 Die bonder and die bonding method

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116504710A (en) * 2023-06-25 2023-07-28 广东芯乐光光电科技有限公司 Mini-LED die bonding device and die bonding method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116504710A (en) * 2023-06-25 2023-07-28 广东芯乐光光电科技有限公司 Mini-LED die bonding device and die bonding method
CN116504710B (en) * 2023-06-25 2023-12-29 广东芯乐光光电科技有限公司 Mini-LED die bonding device and die bonding method

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