Low-Temperature Semiconductor Testing Adhesive Tape
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Solution Overview
Problem
Conventional methods for testing no-leads-packages semiconductor devices in strips face challenges at low temperatures due to warping of the metal lead frame and tape distortion during singulation, limiting testing to ambient temperatures.
Innovation Solution
A method involving a partially cut semiconductor device strip secured with a specialized adhesive tape, such as KAPTON™ film, that maintains adhesion below -20°C or -50°C, preventing warping and allowing for proper testing alignment and parallelism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the metal lead frame strip is exposed to low temperatures below -20°C, then the semiconductor devices can be tested for low-temperature performance, but the strip experiences significant warping that causes testing failure
Solution Approach 1:
The patent applies parameter changes by modifying the material properties of the adhesive tape to maintain dimensional stability at low temperatures. The adhesive tape is specifically selected or formulated to have low thermal contraction and maintain adhesion strength below -20°C, counteracting the warping tendency of the metal lead frame when exposed to cryogenic temperatures.
Solution Approach 2:
The adhesive tape serves as an intermediary between the metal lead frame strip and the test environment. It mediates the thermal stress by providing a compliant layer that absorbs dimensional changes, preventing direct transmission of warping forces to the semiconductor devices and maintaining proper alignment during low-temperature testing.
2Ease of operation
If the semiconductor devices are fully separated (singulated) for low temperature testing, then individual device testing is possible, but tape distortion affects alignment and spacing between devices
Solution Approach 1:
The patent applies preliminary action by performing partial cutting of the lead frame strip before low-temperature testing, rather than complete singulation. This preliminary isolation removes enough material to prevent electrical shorts between adjacent devices while maintaining the mechanical integrity of the strip and the adhesive tape, thereby preserving alignment and spacing precision.
Solution Approach 2:
Instead of performing complete singulation (excessive action), the patent uses partial cutting that removes just sufficient material to achieve electrical isolation. This partial action is enough to prevent shorts but maintains the structural continuity needed to prevent tape distortion and preserve device alignment.
3Strength
If conventional adhesive materials are used on the test chuck, then the strip can be held in place, but the adhesive fails to maintain adhesion at temperatures below -20°C
Solution Approach 1:
The patent applies parameter changes by selecting an adhesive material with specific thermal properties that maintain adhesion strength at cryogenic temperatures. The adhesive's glass transition temperature, modulus, and bonding characteristics are optimized for low-temperature service, ensuring it remains flexible and adhesive rather than becoming brittle and failing.
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
Enables reliable low-temperature testing of semiconductor devices without altering their thermal properties, reducing warping and alignment issues, and facilitating efficient device singulation and inspection.
Implementation Method 1
placing the strip on an adhesive tape configured for use at temperatures extending below −20° C.
Implementation Method 2
exposing the test chuck, strip, and tape to temperatures below an ambient temperature
Data Source
AI summary
A method for testing a plurality of semiconductor devices arranged on a strip may include forming an array of semiconductor devices on a frame, wherein contact pads of adjacent semiconductor devices are shorted, partially cutting the strip to electrically isolate individual semiconductor devices in the array, placing the strip on an adhesive tape configured to withstand low temperatures (e.g., below −20° C. or below −50° C.), arranging the strip and tape on a test chuck, exposing the test chuck, strip, and tape to temperatures below an ambient temperature and testing the plurality of semiconductor devices while exposed to a low temperature. In one embodiment a KAPTON™ film is used as the adhesive tape.