Semiconductor Base Edge Protrusion to Prevent Via-Hole Cracks
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Solution Overview
Problem
In semiconductor devices, particularly high-frequency integrated circuits, the risk of cracks during die bonding due to foreign substances adhered to the substrate surface is high, leading to reduced yield and increased parasitic inductance, as the linear expansion coefficient mismatch between solder and substrate materials can cause stress concentrations around via holes.
Innovation Solution
A semiconductor device design featuring a base member with a protrusion portion at the circumferential edge, which creates a gap between the device and the assembly board, preventing foreign substances from concentrating stress and reducing the likelihood of cracks, while maintaining electrical connectivity through via holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder material is used for die bonding, then electrical connectivity is achieved, but solder material may creep into via holes causing cracks due to linear expansion coefficient mismatch
Solution Approach 1:
A protrusion portion made of a material different from both the base member and solder material is introduced as an intermediary between the solder material and the via hole. This protrusion portion acts as a barrier that prevents solder material from creeping into the via hole while allowing the solder to maintain its bonding function, thereby eliminating the harmful effect without compromising the electrical connectivity.
Solution Approach 2:
The circumferential edge of the base member is segmented by forming protrusion portions at specific locations rather than creating a continuous barrier. This segmentation approach effectively blocks solder material from reaching via holes at critical positions while maintaining overall structural integrity and allowing solder flow in non-critical areas.
2Reliability
If foreign substances are removed from substrate surface, then crack risk is reduced, but complete removal is difficult and productivity decreases
Solution Approach 1:
The protrusion portions are formed on the base member before the die bonding process, creating a preventive barrier structure in advance. This preliminary action eliminates the need for extensive foreign substance removal operations, as the protrusion portions will prevent any remaining foreign substances from causing cracks during bonding, thereby maintaining high productivity while ensuring reliability.
Solution Approach 2:
Instead of requiring perfect cleaning of the substrate surface, the invention accepts the presence of foreign substances and converts the potential harm into a benefit by using protrusion portions to contain and isolate these foreign substances, preventing them from causing cracks while avoiding the need for time-consuming removal processes.
3Reliability
If via holes are used for grounding, then parasitic inductance is reduced, but foreign substances can cause cracks around via holes
Solution Approach 1:
The protrusion portions serve as intermediary protective structures positioned between foreign substances and the via holes. These protrusions absorb and distribute the impact forces from foreign substances, preventing stress concentration at the via hole locations while maintaining the via holes' essential function of reducing parasitic inductance through direct grounding paths.
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 design effectively prevents cracks and reduces parasitic inductance, enhancing the productivity and reliability of semiconductor devices by ensuring that foreign substances do not concentrate stress on the via holes during bonding.
Implementation Method 1
a portion around the via hole may be cracked by an impact
Implementation Method 2
a via hole which forms a hole shape provided with the front face electrode as a bottom and being open onto another surface, and through which the front face electrode and the rear face electrode are electrically connected to each other
Implementation Method 3
if the solder material whose linear expansion coefficient differs from that of the substrate creeps up into the via hole, a risk arises that a crack will occur by a temperature change
Data Source
AI summary
A semiconductor device is configured to include: a base member of a semiconductor material which forms a thin plate shape; a front face electrode which is placed on a front surface of the base member; a rear face electrode which covers a rear surface of the base member; and a via hole which forms a hole shape provided with the front face electrode as a bottom and being open onto the rear surface, and through which the front face electrode and the rear face electrode are electrically connected to each other; wherein, at a circumferential edge portion of the base member on its side where the rear surface is located, a protrusion portion which protrudes in a thickness direction is disposed.