We use RTX system and WINPC32 to integrate the entire flip chip machine, and the entire structure as shown. We take the computer as a control center, and then take the LD5017 as a sensor to capture with external information and take the PCI 8516 as actuator to control the relay that is the switch of the solenoid valve and output the triangle wave to the IDE. The image in the IP camera that is aligned by the micro-stepping mechanism can be transmitted by the TCP/IP to the computer. And the computer can control the SmartMotor and the power supply via rs232 to achieve the force control. In the computer, we use WINPC32 to do the logic decision. The improved flip chip machine integration architecture is as shown Figure4.1.
And its operation process is as follows
1. The SmartMotor moves the force control mechanism to the Bonding position, and the relay control the five solenoid valves let the carrying platform float or suck five times in order to achieve that the carrying platform and the top plane of plane is coplanar
2. The SmartMotor moves the force control mechanism to the initial position, and the users place the chip.
3. Chip placement completed, the SmartMotor moves the force control mechanism to the Bonding position and open the heater.
4. To control the three IDE makes the chip aligned in the plane.
5. Plane Alignment is completed, and the first stage of the force control use the SmartMotor, power supply control the electromagnet current to
6. Heated a few seconds, and cooling.
7. Cooling is completed, and the SmartMotor moves the force control mechanism to the initial position.
4.1 Coplanarity part
When the SmartMotor moves the force control mechanism to the Bonding position, and the relay control the five solenoid valves let the carrying platform float or fixed. First, the relay let the solenoid valve of aeration open and the relay let the solenoid valve of aspirator close, and the carrying platform floats. Next, the relay let the solenoid valve of aspirator open and the solenoid valve of aeration close, and the carrying platform is fixed. Repeat five times, We will find out the value by the force sensor measure when the solenoid valve of aeration open and the relay let the solenoid valve of aspirator close will gradually become same, and the carrying platform and the top plane of plane is coplanar. The solenoid valve arrangement is as shown Figure4.3.
4.2 Force Control part
The flip-chip mechanism is designed the Z-axis localization and the force control organization. Using the SmartMotor actuates the lead screw to do the platform moving in the first stage. The second stage use electromagnet and spring to slowly rise the platform to the position of the pressure, then recombines load cell which display the pressure value, makes the force feed back to control magnetic force size of the electromagnet to reach the expected force resolution. The localization
and the force control organization contain the lead screw, the step motor, the compression spring, the load cell, the electromagnet. In the second stage, the main linkage strength is depended on the electromagnet current to decide. And the RS232 program process is shown in Figure4.4.
4.2.1 First stage
Using the DC servomotor with the lead screw, the linear slide, and the belt do the Z axis vertical positioning systems, and increases the motor torsion by using the speed reducer that reduction gear ratio is 10:1, then the Z axis platform of the most high loading increase, and uses 2000 counts/rev encoder to read SmartMotor step to do feed back control.
There are three limit switches to observe the platform path domain to prevent to hit machine.
When the user enters the desired force value, the motor will slowly put the flip chip mechanism up, and the chip on the carrying platform will touch the upper substrate, then the force value is increased. When the force value increased over the input values few 50, the motor will stop, completed the first stage force control.
4.2.2 Second stage
Take the DC electromagnet, the spring and the load cell does as the flip chip linkage force control system. This organization takes advantage of the characteristic of electromagnetic force with the magnetic material.
Controlling the linkage force is executed because of us gives electromagnet the initial current first and has the electromagnetic force.
springs to compress. There is 200g preload. After the localization is completed, we reduce gradually the electromagnetic current by once 0.001A to reduce electromagnetic force, when the electromagnetic force is smaller than the spring’s strength, they will cause the sliding panel with the carrying platform to receive spring's upward thrust force. But the carrying platform already compresses the chip, therefore the sliding panel will receive the upward thrust force of a small upward displacement. The upward thrust force by small displacement will create force, also will be the linkage force which we will control.
When the first stage of the force control is end, we reduce gradually the electromagnetic current by once 0.001A to reduce electromagnetic force until the new force value is equal to the enter value. The resolution is shown as Figure4.5.
4.3 Plane Alignment part
Piezoelectric actuator is an efficient driver for micro-stepping mechanism, and it comes with several advantages such as its power-saving function, less noise, compact size, sensitivity, and high precision.
On the carrying platform top, we put three sets of IDM, as shown Figure4.6. Using the PCI 8516, output the anything style triangular wave in order to control the output of three sets of IDM, along with the observation by CCD, as shown Figure4.7. The translation and rotation experiment towards the 2-D ( 2-Dimension) of 3-DOF ( 3- Degree Of Freedom) micro-stepping mechanism is eventually for deliberating the
movement relationship between different driving waves done to the same mechanism. The users can operate the movement by exchange the parameters freely with Human Machine Interface and then capably gain the precise positioning.
We mark some frames on the chip to be an aligned mark, as shown Figure4.8. The frame’s size that will be aligned mark is the same with substrate, as shown Figure4.9. We can change the ratio of the three triangle waves, we can move the chip to the aligned placement. When the frame on the chip is overlapped with the substrate, the plane alignment is finished, as shown Figure4.10.