Research On Lead Frame Carrier System Of Vertical LED High Speed Wire Bonder

Wire bonder is semiconductor packaging equipment,which is the one of the key equipment required in the production of LED(Lighting Emitting Diode).The lead frame(LF)carrier system as an important part of the wire bonder,the main function is to drive the LF transmission and fixed LF welding position.Speed and positioning accuracy of the LF carrier system directly affect the overall performance of wire bonder.The LED high speed wire bonder has higher speed and precision,it has theoretical significance and practical value to study the mechanical structure,transmission mode and motion control of the lead frame carrier mechanism.In this paper,the design of the LF carrier system of the vertical LED wire bonder reference to the same equipment at home and abroad,according to the requirements of welding technology,designed the entire LF carrier system structure and motion control process.The specific contents of the paper are as follows:(1)The design of LF carrier deviceThe design of the LF carrier device mainly includes tray,pusher,clamp,puller mechanism,and so on.Designed the overall type of LF tray and pusher mechanism,which is more convenient and reliable for adjusting the lead frames with different height.Reducing the weight of the LF pusher mechanism,and then LF pusher mechanism directly connect to the LF rail of tray,so that it is linkage adjustment.When the sensor of LF detects a lead frame,the pusher motor will pushes the LF to the appointed location of the LF tray mechanism.Designed the modular and multi pieces translational LF clamp mechanism,which has the characteristics of lamp-cup of good applicability,and reliable compression deformation.In order to reduce the time of LF carrier,the clamp assembly will simultaneously press the multi lamp-cups modular clamp,which can be pressed more than a number of lamp-cups,according to the need to match a different number of clamps.In the process of clamping and opening the lamp-cup,the clamp can reduce the friction and deformation between the clamping force and the lamp-cup by using the horizontal translation method,which can ensure that the welding surface of the lamp-cup is level,and the welding wire stability is improved.Due to the small stroke of the clamp,the clamp assembly uses the lever assembly to enlarge the force,and the voice coil motor directly drives.Through changing the electrical parameters,it can be adjust the clamp force of clamp.Designed a voice coil driven LF puller mechanism,which are double grippers mechanical linkage,time-sharing.It is not only to reduce the moving components,but also to ensure the speed and accuracy of LF carrier.The design of the voice coil motor and the double grippers assembly of the LF puller mechanism directly drive the LF transmission,Through high speed of voice coil motor and grating of feedback motor position,can be ensured position accuracy and speed of the LF carrier.The left(index)gripper is responsible for pulling the LF from the LF tray mechanism into the clamping position of the LF clamp mechanism,the right(eject)gripper is responsible for pulling the LF from the clamping position to the unload mechanism.As the voice coil motor with high speed and high precision,left and right grippers can be individually or time-controlled to opening or clamping the LF.Through an optical fiber sensor detects the small holes in the stent of the LF,it is sure the position of LF.(2)The design of the control systemFirstly,the control experiment scheme of the LF carrier mechanism is designed.This paper introduces and analyzes the various components and practical requirements of the hardware system of the LF carrier control system.The control process is described,which the pusher and tray motor are controlled by the control module of the single chip microcomputer,and the clamp and puller motor are controlled by Turbo PMAC motion control card,and the related electrical components are selected and the relevant experimental prototype is built.Secondly,according to the position control method of puller motor,the algorithm of multi-stage PID control strategy with multi-stage displacement,variable speed / acceleration feedforward is designed,and through the following two aspects to verify to shorten time and the position precision within 50 um.On the one hand,the internal S-curve algorithm and PID servo setting of Turbo PMAC control card are studied,and the position control strategy of the puller motor has analyzed,and the reliability of the trajectory control of the puller motor has verified by experiments.On the other hand,according to the actual requirements of the image and the motor to move the relationship between the location of the relationship,and in accordance with this relationship to confirm the position of moved LF,in order to verify the effect of puller motor control.Further,a 20-pieces LF with one index distance spacing of 7.62 mm,each moving 6 index pitches spacing(38.1mm)was tested.According to the above two aspects of the detection process,on the basis of the multi-stage PID control,use variable speed/acceleration feedforward gain to respectively test two or three displacement.Through grating read data and image matching corresponding position,the final positioning accuracy is controlled within 0.05 mm and the time is controlled in 120 ms,compared to time of single-stage displacement reduced by 1/3.Finally,according to the experimental scheme,the software system has developed,the prototype test has completed,and the feasibility of the scheme has verified.The software control module related to the LF carrier control system has introduced,and the related software has wrote in the VS2010 environment.It has completed the test of the related experiments,and it will provides a reference for the practical application.