Hybrid Ball and Wirebond Packaging for Thermal-Stable Die Connections
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Solution Overview
Problem
Conventional semiconductor device packaging methods, such as wirebonding and flip-chip packaging, are time-consuming and expensive, and there is a need for more efficient and cost-effective techniques that allow for both solder bumps and leads to provide robust electrical connections.
Innovation Solution
A packaged semiconductor device design that partially encapsulates the die, exposing a central region for bump bonding or ball grid array connections, with leads extending beyond the encapsulant to provide additional electrical connections and mechanical anchoring, using a combination of wire bonds and solder balls or metal pillars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wirebonding is used to connect contact pads to leads, then electrical connections are established, but the process is time-consuming and expensive
Solution Approach 1:
The patent combines wirebonding technology with bump bonding technology in a single packaging structure. Wirebonds connect peripheral contact pads to leads, while solder bumps connect central contact pads directly to the substrate, merging two different interconnection methods to achieve both reliability and efficiency
Solution Approach 2:
The contact pads are segmented into two groups: peripheral contact pads connected via wirebonds to leads, and central contact pads connected via solder bumps directly to the substrate. This segmentation allows different connection methods to be applied optimally to different regions
2Productivity
If flip-chip packaging with solder balls is used, then packaging efficiency is improved, but all contact pads must be exposed requiring complete die exposure
Solution Approach 1:
The encapsulant is applied with local quality variation: the central region containing contact pads for bump bonding is left exposed, while peripheral regions are encapsulated. This selective exposure allows efficient bump bonding in the center while maintaining protective encapsulation where needed
Solution Approach 2:
Instead of completely exposing the die as in flip-chip packaging, only the necessary central region is partially exposed for bump bonding, while the rest of the die remains encapsulated, reducing complexity and protecting unnecessary areas
3Strength
If solder balls are deformed during mounting, then mechanical connection to substrate is achieved, but lead deformation is required
Solution Approach 1:
The mechanical connection function is segmented between solder bumps and leads: solder bumps provide the primary mechanical anchoring to the substrate through deformation, while leads maintain their positioning precision for electrical connections, dividing the deformation requirement from the precision requirement
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
This design enables efficient electrical connections with reduced deformation of solder balls and leads, allowing for differential thermal expansion and improved mechanical stability during mounting on a circuit board, while minimizing manufacturing time and costs.
Implementation Method 1
the solder balls may be somewhat deformed or 'squashed' whilst allowing the leads to provide further electrical connection
Implementation Method 2
provide a degree of tolerance allowing for differential thermal expansion during use
Data Source
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AI summary
Disclosed is a packaged semiconductor device, comprising: a semiconductor die, having an array of contact pads, in a central region of a first major surface thereof and for contacting to an array of solder balls; encapsulant, partially encapsulating the semiconductor die and having an aperture in a first major surface thereof exposing the array of contact pads; and a plurality of leads extending from side faces of the encapsulant and extending beyond the first major surface of the encapsulant. Corresponding methods are also disclosed.