Double-Sided PCBA BGA Rework With Heat Shielding and Cooling
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Solution Overview
Problem
Existing methods for removing defective BGA chips from double-sided PCBA assemblies often result in collateral heat damage to adjacent components, particularly in high-density or symmetrically arranged chip configurations.
Innovation Solution
A system comprising a holder for the PCBA, a hot air gun for heating the defective chip, and a movable heat-resistant shield to protect adjacent chips on one side, along with a cooling stage using a heat-dissipative tube and heat-dissipative elements to protect chips on the opposite side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hot air gun is used to heat the defective BGA chip for removal, then the chip can be effectively removed, but adjacent components especially heat-sensitive components may suffer collateral heat damage
Solution Approach 1:
The system divides the PCBA into multiple zones using movable heat shields that can be positioned to segment the thermal field. The shields create separate heating zones, allowing the defective chip to be heated while isolating adjacent components from excessive heat exposure.
Solution Approach 2:
Movable heat shields serve as intermediary elements between the hot air gun and the PCBA components. These shields intercept and redirect hot air flow, acting as a mediator that protects heat-sensitive adjacent components while allowing sufficient heat to reach the defective chip for removal.
2Loss of time
If higher heat is applied to remove the defective chip faster, then removal time is reduced, but the risk of collateral heat damage to adjacent components increases
Solution Approach 1:
The heat shields are designed to be movable rather than fixed, allowing dynamic adjustment of their positions during the heating process. This enables real-time optimization of heat distribution, concentrating heat on the defective chip while dynamically protecting adjacent components as the heating progresses.
Solution Approach 2:
The system allows for changing thermal parameters (heat distribution pattern) during the removal process by adjusting shield positions. This enables maintaining high heat concentration on the target chip while controlling overall thermal exposure to adjacent components, effectively decoupling removal speed from collateral damage risk.
3Object-affected harmful factors
If cooling agents are used to protect adjacent components during heating, then some heat protection is achieved, but the cooling agents may interfere with the heating effectiveness on the defective chip
Solution Approach 1:
The system extracts the cooling function from the heating zone by using movable heat shields to physically separate the thermal fields. Instead of introducing cooling agents into the heating zone, the shields redirect hot air flow away from adjacent components, maintaining heating effectiveness on the target chip while protecting surrounding areas without interference.
4Object-affected harmful factors
If rework BGA chip isolation is implemented to protect adjacent chips, then heat protection is improved, but the system complexity and setup time increase
Solution Approach 1:
The heat shields are designed to be movable and repositionable, allowing the same isolation structure to be dynamically adjusted for different chip locations and configurations. This reduces overall system complexity compared to having fixed isolation structures for every possible chip position, as the movable shields can be configured as needed.
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
Effectively removes defective BGA chips from double-sided PCBA while minimizing heat damage to adjacent components, even in high-density or symmetrically arranged configurations.
Implementation Method 1
heating with hot air gun
Implementation Method 2
cooling source feeding cooled air via a heat-dissipative tube towards the location of the PCBA
Implementation Method 3
heat-dissipative tube that can be covered with a thermal-resistant coating or wrapping along the length of the tube, leaving an end of the tube exposed
Implementation Method 4
at least one heat-dissipative element (e.g., a heat sink) that is to the side of the heat-dissipative tube that comes into contact with adjacent BGA chips on the second side of the PCBA via heat-dissipative media (e.g., thermal paste) on the surface of the at least one heat-dissipative element
Data Source
AI summary
A system for dismantling defective BGA chips from double-sided PCBA having a fix stage and a cooling stage. The fix stage includes at least one shield that prevents hot air from a hot air gun to heat BGA chips that are adjacent to the defective BGA chips. The cooling stage prevents overheating of the BGA chips that are on the opposite side of the double-sided PCBA by conducting heat away from the BGA chips during the process.