Sensor Package Cavity Structure Without Specialized Mold Chases
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Solution Overview
Problem
Existing semiconductor packages face challenges in forming cavities for sensors due to the need for expensive and tedious specially-designed mold chases, alignment issues, and exposure of bond wires, leading to increased complexity and cost.
Innovation Solution
A semiconductor package design that utilizes a metal ring and tie bar structure to define a cavity, omitting bond wires, allowing for uniform metal ring and pillar heights, and eliminating the need for specialized mold chases, resulting in thinner, lighter, and less expensive packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If specially-designed mold chases are used to form cavities for sensors, then the cavity can be formed, but the manufacturing cost and complexity increase
Solution Approach 1:
The patent extracts the cavity formation function from the mold chase design and relocates it to the sensor package structure itself. The metal ring and pillar are positioned within the package to define the cavity, eliminating the need for specialized mold chase features and simplifying the molding process.
Solution Approach 2:
The metal ring and metal pillar serve as intermediary structures that define the cavity space. These components act as physical barriers and spatial definers during the molding process, allowing standard mold chases to be used while still achieving precise cavity formation.
2Reliability
If bond wires are used to couple the chip to leads, then electrical coupling is achieved, but the package thickness increases and alignment issues occur
Solution Approach 1:
The patent removes bond wires from the package structure and replaces them with direct electrical coupling methods. The sensor is electrically connected to the lead frame through alternative means such as direct attachment or integrated contact structures, eliminating the need for bond wires and reducing package thickness.
3Reliability
If bond wires are used for electrical coupling, then connectivity is achieved, but manufacturing alignment becomes difficult and time-consuming
Solution Approach 1:
The patent eliminates bond wires and their associated alignment requirements. The sensor is electrically coupled to the lead frame through methods that do not require precise manual or automated wire placement, such as direct mounting with integrated electrical contacts or snap-fit connections, significantly reducing manufacturing time.
4Reliability
If the metal ring height is increased to cover bond wires, then wire protection is achieved, but the package becomes thicker and heavier
Solution Approach 1:
The patent removes bond wires from the package, eliminating the need for the metal ring to extend high enough to cover them. The metal ring can be shorter and serve only its primary function of defining the cavity, thereby reducing the overall package height, weight, and volume.
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 reduces manufacturing time, complexity, and cost by ensuring mold compound does not enter the cavity, enabling efficient alignment and reducing the package's thickness, weight, and eliminating the need for specialized tools.
Implementation Method 1
The tie bar is coupled with solder to the top metal ring surface... the horizontal member is soldered to the top metal pillar surface
Implementation Method 2
The mold compound contacts the exterior metal ring surface, with the mold compound absent from the cavity
Data Source
AI summary
In examples, semiconductor package comprises a semiconductor die having a device side including circuitry; a sensor on the device side; a metal ring on the device side to at least partially define a cavity vertically aligned with the sensor, with the metal ring having a top metal ring surface facing away from the semiconductor die and an exterior metal ring surface facing away from the sensor; and a metal pillar on the device side and having a top metal pillar surface facing away from the semiconductor die. The package also comprises a tie bar extending approximately parallel to the device side of the semiconductor die and coupled with solder to the top metal ring surface, with the tie bar exposed to a first exterior surface of the package. The package comprises a conductive member including a conductive terminal exposed to a second exterior surface of the package, a vertical member coupled to the conductive terminal and extending toward the first exterior surface of the package, and a horizontal member coupled to the vertical member, with the horizontal member soldered to the top metal pillar surface. The package comprises a mold compound contacting the exterior metal ring surface, with the mold compound absent from the cavity.