Semiconductor Package Cavity Structure for Millimeter Wave Signal Integrity
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Solution Overview
Problem
Conventional semiconductor package devices using high dielectric constant materials like epoxy resin cause signal distortion and interference with millimeter waves due to differences in dielectric constants, affecting signal conduction speed and quality.
Innovation Solution
A cavity structure is introduced within the package device to isolate the high-sensitive integrated circuit from package materials, using a second die with a cavity structure as a cap to prevent direct contact with epoxy resin, thereby maintaining signal integrity by using a polymer material to encapsulate the conductive wires and dies without encapsulating the pads, and forming an inverse U-type cavity between the dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy resin with high dielectric constant is used to encapsulate the package device, then the package body is protected and conductive wires are secured, but signal distortion and interference occur due to dielectric constant differences
Solution Approach 1:
The package structure is divided into two distinct regions: a first region containing the high-sensitive integrated circuit without epoxy resin, and a second region containing other components with epoxy resin encapsulation. This segmentation allows the sensitive circuit area to avoid dielectric interference while other areas maintain protection, resolving the contradiction between package protection and signal quality.
Solution Approach 2:
Different regions of the package are assigned different material properties: the first region has no epoxy resin to maintain signal integrity for millimeter wave transmission, while the second region has epoxy resin encapsulation for protection. This local differentiation of material quality allows simultaneous achievement of signal fidelity and package protection in different areas.
2Strength
If epoxy molding compound with dielectric constant larger than 4 is used to protect conductive wires, then wire protection is improved, but signal decay and distortion occur during wave conduction
Solution Approach 1:
The package is segmented into a first region without epoxy resin for housing the integrated circuit and conductive wires, and a second region with epoxy resin for protecting other components. This segmentation allows conductive wires to be protected from mechanical damage while avoiding dielectric interference that causes signal decay, thus resolving the contradiction between wire protection and signal conduction quality.
3Adaptability or versatility
If different materials with different dielectric constants are used in the package, then material functionality is optimized, but signal distortion is generated due to different wave-conduction speeds
Solution Approach 1:
The package structure is divided into a first region without epoxy resin for millimeter wave transmission and a second region with epoxy resin for other components. This segmentation isolates the sensitive signal path from materials with different dielectric constants, allowing material versatility in different regions while preventing signal distortion in the critical transmission path.
Data Source
AI summary
A semiconductor device with a cavity structure comprises: a carrier substrate; a first die having an active surface and the pads thereon; a back surface of the first die is disposed on the carrier substrate; a second die having a top surface and a back surface and a cavity structure therein; the top surface of a second die is flipped to dispose on the first die, and the cavity structure is an inverse U-type to dispose between the active surface of the first die and the top surface of the second die; the wires is electrically connected the pads with the first connecting points; a package body encapsulated the first die, the second die, the wires, and the portion of the top surface of the carrier substrate; and the connecting components is disposed on the back surface of the carrier substrate and is electrically connected the second connecting points.