Burn-in Oven Ventilation Control for Rapid Thermal Cycling
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Solution Overview
Problem
Current burn-in methods for electronic equipment using thermal cycling face limitations in achieving rapid temperature variations due to thermal inertia and heat exchange issues, requiring costly and risky disassembly or excessive oven performance, and high nitrogen consumption.
Innovation Solution
The method involves temporarily suspending ventilation during temperature transitions to allow the oven to rapidly change temperature, restarting ventilation when the temperature disparity is maximal, and using a control circuit to manage ventilation flow, thereby achieving instantaneous transitions for the equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If ventilation is increased to improve heat exchange, then heat exchange efficiency is improved, but temperature variation speed at the equipment remains insufficient due to thermal inertia
Solution Approach 1:
The ventilation system operates periodically rather than continuously - it is activated during temperature stabilization phases and deactivated during rapid transition phases. This periodic operation allows the system to achieve both efficient heat exchange when needed and rapid temperature transitions when ventilation is suspended, resolving the contradiction between heat exchange efficiency and temperature variation speed.
2Loss of energy
If equipment is disassembled to expose boards for direct air contact, then heat exchange is improved, but manufacturing complexity and risk increase
Solution Approach 1:
The ventilation system is made dynamically controllable, allowing it to be adjusted or suspended during critical transitions. This dynamic control enables the equipment to remain assembled while still achieving rapid temperature variations by temporarily stopping ventilation, thus improving heat exchange efficiency without requiring disassembly and reducing manufacturing complexity.
3Speed
If oven temperature variation capacity is increased to achieve faster equipment temperature changes, then temperature variation speed is improved, but equipment cost increases
Solution Approach 1:
The ventilation system serves as an intermediary mechanism that enables rapid temperature transitions without requiring an oversized oven. By suspending ventilation during transitions, the system leverages the oven's existing capacity while using ventilation control as the mediating factor to achieve faster temperature changes, thereby avoiding the need for expensive high-capacity oven equipment.
4Speed
If liquid nitrogen is used for rapid cooling, then cooling speed is improved, but operational cost increases due to nitrogen consumption
Solution Approach 1:
The system uses its own ventilation infrastructure to achieve rapid cooling by suspending it during transitions, rather than relying on external liquid nitrogen. This self-service approach leverages the existing ventilation system's capacity and eliminates the need for costly nitrogen consumption, thereby achieving fast cooling speed without increased operational costs.
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 enables faster temperature variation at the equipment without disassembly, reducing costs and risks, while allowing the use of less expensive, lower-performance ovens to achieve equivalent stress levels, optimizing oven usage and improving temperature gradient steepness.
Implementation Method 1
The heating system usually is based on electrical resistances
Implementation Method 2
a refrigerating machine comprising a cold unit, an evaporator and a condenser
Implementation Method 3
a refrigerating machine comprising a cold unit, an evaporator and a condenser
Implementation Method 4
a system based on injection of liquid nitrogen into the oven with gasification of the nitrogen in the oven
Implementation Method 5
the temperature variations of the oven are passed on to the equipment through exchange of calories between the air of the oven and the equipment
Implementation Method 6
the second physical phenomenon is the thermal inertia of the equipment which counters temperature variations by storing calories
Data Source
AI summary
An equipment burn-in method, which includes the equipment undergoing treatment in an oven, the oven undergoing cycles including at least one temperature-rise and/or temperature-fall transition, for which ventilation of the equipment is cut off during at least part of a temperature transition of the oven.