Test Socket Gas-Flow Cooling for Solder Ball Temperature Control
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Solution Overview
Problem
Existing test systems for integrated circuits face issues such as solder ball melting and deformation due to excessive localized temperatures, difficulty in controlling base die junction temperature in stacked packages, and the need for redesigning test sockets for temperature measurement, leading to potential damage and high repair costs.
Innovation Solution
A test socket design with a channel for gas flow that cools spring probes, using a closed-loop temperature control system to maintain desired temperatures, compatible with existing systems and avoiding the need for larger probes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional test sockets are used without gas flow cooling, then the test system structure is simple, but the localized temperature exceeds the solder melting point causing solder ball deformation and damage
Solution Approach 1:
The test socket is segmented into multiple functional components: a body portion, a probe cartridge with spring probes, and an integrated gas flow cooling system with inlet and outlet ports. This segmentation allows the cooling function to be added as a distinct module rather than redesigning the entire socket structure.
Solution Approach 2:
A gas flow (typically nitrogen or compressed air) is introduced as an intermediary cooling medium between the heat source (spring probes and DUT) and the environment. The gas flows through channels in the probe cartridge, absorbing heat and preventing solder ball melting without requiring direct thermal contact or complex active cooling systems.
2Measurement precision
If temperature measurement devices are added to monitor DUT temperature, then temperature control capability is improved, but the test socket requires redesign and probe size/length must increase
Solution Approach 1:
The spring probes serve multiple functions: they provide electrical signal transmission to/from the DUT, act as thermal conduction paths, and function as temperature sensing elements through resistance temperature detection. This multi-functionality eliminates the need for separate temperature measurement devices and their associated infrastructure.
Solution Approach 2:
The test system uses its existing spring probes to self-monitor temperature by measuring probe resistance, which varies with temperature. This self-service approach allows temperature monitoring without adding external sensors or redesigning the socket, as the probes inherently provide both testing and temperature sensing functions.
3Reliability
If gas flow cooling is implemented in the test socket, then solder ball melting is prevented, but the test socket structure becomes more complex with additional inlet and outlet ports
Solution Approach 1:
The gas flow cooling system is merged with the existing probe cartridge structure. The inlet and outlet ports are integrated into the cartridge housing, and gas flow channels are formed within the existing probe support structure. This merging allows cooling functionality to be added without creating a completely separate system or significantly increasing overall complexity.
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 controls temperatures to prevent solder ball melting, reduces damage risk, and integrates seamlessly with existing test systems without requiring redesign.
Implementation Method 1
an inlet configured to introduce a gas into the channel... an outlet configured to exhaust the gas away from the channel. The gas cools at least a portion of the plurality of test spring probes included in the probe field
Data Source
AI summary
Various embodiments include techniques for controlling temperature of a test socket in a test system. A temperature controller determines an input temperature associated with a reference device under test (DUT) mounted in the test socket. The temperature controller determines a flow rate of a gas based on the input temperature. The temperature controller adjusts a flow control valve to supply the gas to the reference DUT at the flow rate.