Flip Chip Reworking via Milling and Automated Placement
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Solution Overview
Problem
Existing methods for replacing defective semiconductor chips in electronic assemblies are costly, time-consuming, and can damage devices, making it difficult to efficiently rework flip chip mounting without discarding expensive equipment.
Innovation Solution
A system and method utilizing a mill to remove the old flip chip and underfill, followed by precise placement and reflow of a new flip chip, with automated processes for milling, cleaning, fluxing, and heating to secure the new chip, facilitated by a machine that includes a mill, pick-and-place device, and heater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If conventional reworking methods are used to replace defective chips, then chip replacement can be achieved, but the process is costly, time-consuming, and can damage the electronic device
Solution Approach 1:
The patent replaces conventional mechanical reworking methods (which involve manual or semi-automated chip removal and replacement) with an automated milling system that uses controlled material removal to extract defective chips and install new ones. This mechanical system substitution enables precise, repeatable operations that reduce both time and damage risk.
Solution Approach 2:
The patent changes the operational parameters of the reworking process by using automated control systems to precisely manage milling depth, speed, and positioning. These parameter changes enable the process to be completed faster and with greater accuracy than conventional methods, directly addressing the time loss and damage concerns.
2Ease of repair
If conventional reworking methods are used to replace defective chips, then chip replacement can be achieved, but the process is costly and time-consuming
Solution Approach 1:
The patent replaces conventional mechanical reworking methods with an automated milling system that performs chip removal and installation through controlled material removal. This substitution dramatically improves productivity by enabling rapid, precise operations that can be repeated consistently without manual intervention.
Solution Approach 2:
The patent incorporates preliminary alignment and positioning steps that automatically prepare the electronic device for milling before the actual chip removal begins. This preliminary action ensures that the milling process can proceed immediately at full speed without setup delays, thereby improving overall reworking efficiency.
3Ease of repair
If conventional reworking methods are used to replace defective chips, then chip replacement can be achieved, but damage to the electronic device may occur
Solution Approach 1:
The patent replaces manual or semi-automated mechanical reworking with an automated milling system that uses precisely controlled cutting tools. This substitution eliminates the variability and force control issues inherent in manual operations, thereby preventing damage to the electronic device while maintaining ease of repair.
Solution Approach 2:
The patent incorporates feedback mechanisms that continuously monitor the milling process parameters such as tool depth, cutting force, and position. This real-time feedback allows the system to adjust operations dynamically, preventing excessive force or incorrect positioning that could damage the electronic device, thus ensuring safe and effective chip replacement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces reworking time and costs, minimizes damage, and allows for efficient replacement of defective chips within electronic devices, enabling the reuse of expensive equipment and improving efficiency.
Implementation Method 1
milling makes available for mounting conductive pads of the electronic device
Implementation Method 2
heating to cause solder reflow, to secure the new flip chip in place
Implementation Method 3
the solder balls attached to the chip are to be attached to corresponding solderable metal contact pads on the PCB or PCC. However, in this instance, such attachment is not achieved by melting the solder balls because the organic materials comprising the PCB or PCC are incapable of withstanding the temperatures needed to achieve solder ball melting
Data Source
AI summary
A system and method for reworking a flip chip includes use of a mill to remove an old flip chip, and a pick-and-place device for putting a new flip chip in place at the same location. The process may be automated, with the removal and the placement occurring sequentially without need for operator intervention. Other devices and processes may be part of the system/machine and process, for example cleaning following the milling, fluxing prior to the placement, and heating to cause solder reflow, to secure the new flip chip in place. Underfill may be employed to make for a more mechanically robust mounting of the new flip chip.