Bonding Pad Segmentation for Void-Free Solder Joints
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Solution Overview
Problem
Flip-chip type light emitting devices face issues with void formation during the soldering process, which leads to weakened heat dissipation and connection failures, affecting the reliability and efficiency of the devices.
Innovation Solution
A light emitting device with a bonding pad structure that includes elongate opposed regions and a non-conductive region between them, allowing by-products to escape during soldering, and a configuration of electrode pads with fingers to prevent void trapping and enhance current spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bonding pad is soldered to a mounting substrate using conventional methods, then electrical connection is achieved, but voids form during soldering that weaken heat dissipation and connection reliability
Solution Approach 1:
The bonding pad is divided into multiple elongate opposed regions separated by non-conductive regions. This segmentation allows flux bubbles to escape through the non-conductive regions during soldering, preventing void formation in the solder joints while maintaining electrical connection reliability.
Solution Approach 2:
Non-conductive regions are extracted from the bonding pad structure, creating pathways for flux bubbles to escape during the reflow process. This extraction prevents bubble entrapment and subsequent void formation in the solder joints.
2Reliability
If electrode pads are configured with fingers to prevent void trapping, then connection reliability improves, but device complexity increases
Solution Approach 1:
The electrode pads are segmented into finger-like projections that create pathways for flux bubble escape. This segmentation prevents void trapping while maintaining a relatively simple overall pad structure that can be fabricated using standard photolithography techniques.
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 minimizes void formation, improves bonding strength, and ensures uniform current distribution, leading to enhanced luminous efficacy and reliability of the light emitting device.
Implementation Method 1
a solder bump is melted by application of a heat thereto to realize electrical connection between a bonding pad of a chip and a mounting substrate
Implementation Method 2
In the reflow process, a flux is evaporated and may generate bubbles
Data Source
AI summary
A light emitting device in which a bonding pad is soldered to a mounting substrate, wherein the bonding pad may be formed in various shapes that can minimize the occurrence of voids during soldering or heat fusion.