Semiconductor Package Ground Enhancement for High-Frequency Loss
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Solution Overview
Problem
Conventional resin-encapsulated semiconductor packages face challenges in handling high-frequency signals due to low permittivity of the encapsulation resin, leading to impedance mismatch and significant transmission loss, especially at frequencies above 1 GHz, and require costly equipment changes to adjust characteristic impedance.
Innovation Solution
A semiconductor package design featuring a planar lead with an exposed end and an electric conductor for ground enhancement, where the conductor has a smaller cross-sectional area than the main surface area, is encapsulated in resin with the main surface facing the lead, allowing for improved grounding and reduced phase advance, enabling low-loss high-frequency characteristics without the need for equipment changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ground leads are provided on both sides of each signal lead with widths three times or more the width of the signal leads to form coplanar distributed constant lines, then characteristic impedance can be designed, but the package size increases significantly
Solution Approach 1:
The invention transitions from a coplanar configuration (all leads in the same plane) to a microstrip configuration where the ground lead is positioned beneath the signal lead, utilizing the vertical dimension. This dimensional change allows characteristic impedance control without requiring excessive lateral space, thereby reducing package size while maintaining impedance design capability.
Solution Approach 2:
The invention uses the signal lead itself as the ground reference by positioning a ground lead directly beneath it, creating a microstrip transmission line structure. This copying approach eliminates the need for separate wide ground leads while achieving proper impedance matching through the vertical arrangement of signal and ground conductors.
2Area of stationary object
If lead terminals are designed to function as microstrip distributed constant lines with reduced package size, then package area is minimized, but great transmission loss occurs at high frequency bands of 1 GHz or more
Solution Approach 1:
The invention optimizes the geometric parameters of the microstrip transmission line, specifically the width and spacing of the ground lead relative to the signal lead. By carefully controlling these parameters, the characteristic impedance is matched to minimize reflections and reduce transmission loss at high frequencies, while maintaining a compact package size.
Solution Approach 2:
The invention introduces an adjustable ground lead structure that can be positioned at optimal distances from the signal lead. This dynamic adjustment capability allows optimization of the microstrip line characteristics for high-frequency performance, enabling transmission loss reduction while maintaining compact dimensions through precise geometric control.
3Reliability
If equipment is adjusted and changed to modify characteristic impedance, then high frequency characteristics can be optimized, but equipment investment is required
Solution Approach 1:
The invention achieves characteristic impedance optimization through changes in the geometric parameters of the lead terminal structure itself, specifically the width and positioning of the ground lead. This structural parameter adjustment eliminates the need for expensive equipment modifications, as the impedance control is built into the package design through precise lead geometry rather than requiring external equipment changes.
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 solution provides an inexpensive semiconductor package with excellent high-frequency characteristics by enhancing grounding strength and reducing transmission loss, allowing for effective heat dissipation and flexible resin thickness adjustment, thus supporting high-power, high-frequency semiconductor elements.
Implementation Method 1
an electric conductor for ground enhancement having a first main surface and a second main surface opposite to the first main surface, and encapsulated in the resin, the first main surface facing the lead with the resin therebetween, the second main surface being exposed from the resin
Data Source
AI summary
A semiconductor package according to the present invention includes: a semiconductor element where a high frequency signal is input or output; a planar lead terminal having an end electrically connected to an input terminal or an output terminal of the semiconductor element; an encapsulation resin for encapsulating the lead terminal and the semiconductor element, the lead terminal having another end exposed from the resin; and a ground enhancing metal body encapsulated in the encapsulation resin, having a first main surface facing the lead terminal and a second main surface exposed from the encapsulation resin, wherein the ground enhancing metal body has a shape with a cross section parallel to the second main surface and having a smaller area than an area of the first main surface.