Packaged RF Amplifier IPD Integration and Wirebond Isolation
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Solution Overview
Problem
Conventional overmolded RF amplifier devices face challenges in incorporating high-quality integrated passive devices (IPDs) due to package stresses, which degrade performance and can damage the thin IPDs, leading to poorer RF performance and increased device size.
Innovation Solution
The implementation of improved IPD attachment materials and methods, along with physically robust IPDs, allows for reliable incorporation of IPDs into overmolded packages, and the use of wirebond fences and angled wirebonds enhances signal path isolation in multi-path RF amplifier devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-quality integrated passive devices (IPDs) are incorporated into overmolded packages, then RF performance is improved, but package stresses damage the thin IPDs and degrade performance
Solution Approach 1:
A support structure is provided beneath the IPD within the package to prevent damage from molding stresses. This cushioning support is positioned before the molding process to protect the thin IPD substrate during packaging, allowing high-quality IPDs to be incorporated without degradation from package stresses.
2Reliability
If wirebonds are used to couple input/output leads to transistors, then electrical connectivity is achieved, but significant inductances at high frequencies degrade device performance
Solution Approach 1:
The wirebond connections are segmented by introducing intermediate connection points and re-routing through the support structure. This segmentation breaks up long continuous wirebonds into shorter segments, reducing the cumulative inductance while maintaining electrical connectivity between input/output leads and transistors.
Solution Approach 2:
The wirebond routing is moved from a planar configuration to a three-dimensional path utilizing the support structure and package vertical space. This dimensional change allows for shorter effective wirebond lengths and reduced inductance by exploiting the Z-dimension of the package rather than only the X-Y plane.
Data Source
AI summary
An embodiment of a packaged radio frequency (RF) device includes a device substrate with a voltage reference plane, a first input lead coupled to the device substrate, a first output lead coupled to the device substrate, a first transistor die coupled to a top surface of the device substrate with a solder bond, a second die coupled to the top surface of the device substrate with a conductive epoxy that electrically couples at least one component of the second die to the voltage reference plane, and non-conductive molding compound over the top surface of the device substrate and encompassing the first transistor die, the second die, a portion of the first input lead, and a portion of the first output lead.