Polymeric Die Pad Assembly for Chip-on-Lead Die Isolation
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Solution Overview
Problem
Existing semiconductor packages face challenges in reducing costs and footprints while effectively isolating semiconductor dies from leads to prevent current leakage due to conductive debris.
Innovation Solution
Incorporating a polymeric die pad that is electrically non-conductive, attached to the leads and extending laterally past the semiconductor die on all sides, which reduces the risk of current leakage paths and allows for a lower cost and smaller package area by using adhesive attachment methods instead of costly ceramic or rigid fiber reinforced polymer die pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic or rigid fiber reinforced polymer die pads are used, then electrical isolation and reliability are improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive ceramic or rigid fiber reinforced polymer die pads with a polymeric die pad that can be formed from cost-effective materials and manufactured using simpler, lower-cost processes while maintaining adequate electrical isolation performance for the application
Solution Approach 2:
The patent changes the material parameters from traditional ceramic or rigid composite materials to polymeric materials, which have different electrical, mechanical, and thermal properties but provide sufficient electrical isolation while enabling lower manufacturing costs through easier processing and material availability
2Reliability
If ceramic or rigid fiber reinforced polymer die pads are used, then electrical isolation and reliability are improved, but package area increases
Solution Approach 1:
The patent employs a polymeric die pad that can be formed as a thin, flexible structure extending laterally past the semiconductor die on all sides, providing effective electrical isolation in a smaller footprint compared to traditional rigid die pad materials that require larger dimensions for equivalent isolation performance
3Ease of manufacture
If adhesive attachment methods are used, then manufacturing cost decreases, but attachment strength may be reduced
Solution Approach 1:
The patent modifies the attachment method from mechanical or high-temperature bonding to adhesive attachment, changing the bonding mechanism parameters to achieve adequate attachment strength at lower costs and temperatures, suitable for cost-sensitive applications where extreme strength requirements are not critical
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
The polymeric die pad effectively isolates semiconductor dies from leads, reducing the risk of current leakage and enabling lower production costs and smaller package sizes compared to traditional die pad materials.
Implementation Method 1
The polymeric die pad is electrically non-conductive
Implementation Method 2
In some versions of this disclosure, the polymeric die pad may be attached to the leads though a die pad adhesive that is adhered to the polymeric die pad
Data Source
AI summary
A semiconductor package includes a polymeric die pad attached to a plurality of the leads of a lead frame portion. The polymeric die pad is electrically non-conductive. The leads are electrically conductive, and extend to an exterior of the semiconductor package. The polymeric die pad may be punched from a polymeric tape and pressed onto the leads. The polymeric die pad may be removed from a precut polymeric tape and placed on the leads by a pick-and-place operation. A semiconductor die is attached to the polymeric die pad, opposite from the leads. The semiconductor die is electrically isolated from the leads by the polymeric die pad. The polymeric die pad extends laterally past the semiconductor die on all sides. The semiconductor package may be formed by attaching the semiconductor die to the polymeric die pad after the polymeric die pad is attached to the leads.