MEMS Strip Testing via Mold Compound Removal and Substrate Trenching
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Solution Overview
Problem
Current strip testing methods for MEMS devices in a strip form face challenges due to residual stresses from the mold compound, leading to offsetting of device calibration values and the need for a second testing step after singulation, which increases manufacturing costs and time.
Innovation Solution
The method involves removing the entire thickness of the mold compound surrounding MEMS devices and partially separating them by forming trenches through the substrate, which reduces mechanical stress and electrically insulates the devices, allowing for accurate testing without the need for a second testing step after singulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MEMS devices are tested in strip form with mold compound intact, then testing productivity is improved, but residual stresses cause offsetting of calibration values requiring a second testing step
Solution Approach 1:
The method performs the separation of MEMS devices in the strip beforehand, before the testing operation, by removing the mold compound and forming separation trenches. This preliminary action eliminates residual stresses that would otherwise cause calibration offset during testing, thereby maintaining both high testing productivity and calibration accuracy without requiring a second testing step.
2Manufacturing precision
If mold compound is completely removed and separation trenches are formed, then calibration accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The method merges the mold compound removal step with the separation trench formation step into a single integrated process. By combining these two operations, the patent achieves complete separation of MEMS devices with accurate calibration while avoiding the need for multiple separate manufacturing steps, thereby reducing overall manufacturing complexity despite the added precision requirements.
Data Source
AI summary
A method for testing a strip of MEMS devices, the MEMS devices including at least a respective die of semiconductor material coupled to an internal surface of a common substrate and covered by a protection material; the method envisages: detecting electrical values generated by the MEMS devices in response to at least a testing stimulus; and, before the step of detecting, at least partially separating contiguous MEMS devices in the strip. The step of separating includes defining a separation trench between the contiguous MEMS devices, the separation trench extending through the whole thickness of the protection material and through a surface portion of the substrate, starting from the internal surface of the substrate.