MEMS Die Bottom Geometry for Adhesive Bleed-Out Clearance
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Solution Overview
Problem
Existing MEMS die bonding methods face issues with adhesive spread over the ASIC die bonding pad, leading to failed wire bonding, and current solutions involve MEMS size reduction, ASIC size increase, or the use of expensive Die Attach Film adhesive.
Innovation Solution
The solution involves forming a MEMS die with a top part and a bottom part that are contiguous and aligned along the z-direction, with an adhesive layer extending to a non-horizontal surface of the bottom part, ensuring the adhesive fillet does not reach the top part, thereby maintaining MEMS size and avoiding the need for size adjustments or expensive adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MEMS die size is reduced or ASIC die size is increased to improve clearance, then wire bonding reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies dimensionality change by shaping the bottom surface of the MEMS die with non-horizontal surfaces (inclined or vertical faces) instead of a flat surface. This three-dimensional surface configuration allows the adhesive layer to be constrained from spreading laterally toward the bonding pad while still providing adequate clearance, thereby improving wire bonding reliability without changing the planar dimensions of the dies.
Solution Approach 2:
The bottom surface of the MEMS die is segmented into multiple surfaces with different orientations (horizontal and non-horizontal surfaces). This segmentation creates distinct functional zones: the horizontal surface provides bonding area while the non-horizontal surfaces act as barriers to adhesive spread, effectively managing clearance without requiring larger die dimensions.
2Ease of manufacture
If conventional adhesive materials are used without size adjustments, then manufacturing cost is reduced, but adhesive spread over the bonding pad causes wire bonding failure
Solution Approach 1:
By introducing non-horizontal surfaces on the bottom of the MEMS die, the patent creates a three-dimensional adhesive containment structure. This allows conventional adhesive materials to be used without modification while the geometric configuration naturally prevents excessive spread, maintaining both cost-effectiveness and bonding reliability.
Solution Approach 2:
The patent converts the potentially harmful lateral spread of adhesive into a beneficial containment effect. The non-horizontal surfaces, which might otherwise be wasted area, are configured to redirect adhesive flow upward along the surface rather than allowing it to spread harmfully toward the bonding pad, turning a manufacturing challenge into a design solution.
3Reliability
If the adhesive layer is constrained to prevent spread, then wire bonding reliability is improved, but the bonding area is reduced
Solution Approach 1:
The patent utilizes the vertical dimension by configuring non-horizontal surfaces that extend upward from the bottom surface. These surfaces act as physical barriers that constrain adhesive spread in the lateral direction while allowing the adhesive to maintain adequate bonding area through vertical containment, thus preserving both reliability and bonding effectiveness.
Data Source
AI summary
An electronic component is provided that includes a substrate having a top side and a bottom side. The substrate defines a horizontal xy-plane and a vertical z-direction that is perpendicular to the xy-plane. An ASIC die is provided having a top side and a bottom side that is attached to the top side of the substrate. Moreover, a MEMS die is provided that includes a top part and a bottom part, the bottom part including at least one horizontal surface and at least one non-horizontal surface. An adhesive layer extends from the top side of the ASIC die to the horizontal surface and to a portion of the non-horizontal surface of the bottom part of the MEMS die. A bonding pad is attached to the top side of the ASIC die adjacent to the adhesive layer. An electrical connection extends from the bonding pad to the MEMS die.