Current Sensor IC Packaging Insulation for Gap Height and Die Tilt
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Solution Overview
Problem
Current sensor integrated circuit packages face issues with inconsistent gap heights and die tilt due to varying solder bump sizes and isolation tape thickness, leading to compromised magnetic field coupling and potential failure during voltage isolation testing.
Innovation Solution
An insulation structure is introduced between the semiconductor die and the lead frame to control gap height and prevent die tilt, using a combination of polymer film and adhesive tape or epoxy dots to support the die evenly, ensuring consistent magnetic field coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of isolation tape on the primary conductor is increased, then the gap height between the die and the primary conductor is improved, but the solder bumps on the signal leads collapse and the die tilts towards the signal leads
Solution Approach 1:
The insulation structure is divided into multiple portions: a first portion positioned between the die and the primary conductor, and a second portion positioned between the die and the signal leads. This segmentation allows independent control of gap heights at different locations, enabling the die to maintain proper levelness while achieving consistent gap heights throughout.
Solution Approach 2:
Different portions of the insulation structure provide different levels of support at different locations. The first portion compensates for the increased isolation tape thickness by providing additional insulation and support between the die and the primary conductor, while the second portion prevents the die from tilting towards the signal leads. This local differentiation of support characteristics resolves the contradiction between gap height consistency and die levelness.
2Manufacturing precision
If the solder bump size is increased to compensate for thicker isolation tape, then the gap height is improved, but the solder bumps collapse and cause die tilt
Solution Approach 1:
The insulation structure acts as an intermediary element between the die and the lead frame components. Instead of relying on larger solder bumps to achieve proper gap height, the insulation structure provides the necessary support and spacing, eliminating the need to increase solder bump size and preventing solder bump collapse.
3Manufacturing precision
If the die is placed closer to the signal leads to reduce gap height, then the gap height differential is reduced, but the die tilts towards the signal leads compromising magnetic field coupling
Solution Approach 1:
The insulation structure is segmented into portions positioned at different locations (between die and primary conductor, and between die and signal leads), enabling independent control of gap heights. This segmentation allows maintaining uniform gap heights without compromising die levelness or magnetic field coupling efficiency.
Data Source
AI summary
A current sensor integrated circuit (IC) package includes an insulation structure disposed between a semiconductor die and a lead frame to control gap height and prevent the die from tilting and dropping the magnetic field coupling between the die the primary conductor. An insulation structure is disposed between the die and the lead frame such that the die remains level and magnetic coupling remains intact. An insulation structure may control the gap height between the lead frame and the die evenly during transfer molding, by supporting the die across its length and/or width. Epoxy dots are also or instead used to control the gap height and eliminate die tilt.