Passivated Chip Flanks to Prevent Solder Run-Up on PCB Assembly
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Solution Overview
Problem
During the assembly of bare chips with printed circuit boards, solder can run up the flanks of the chip, leading to electrical performance issues due to the semiconductor material used in the chip flanks.
Innovation Solution
A method for fabricating electronic chips with passivated flanks involves forming trenches or cavities between chips, depositing an insulating material in these trenches, and then separating the chips by cutting through the insulating material, thereby creating a barrier that prevents solder from reaching the semiconductor flanks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used to connect chips to printed circuit boards, then electrical connection is achieved, but solder may run up the chip flanks causing short-circuits or leakage current
Solution Approach 1:
An insulating material layer is introduced as an intermediary between the solder and the semiconductor substrate flanks. This layer acts as a barrier that prevents solder from contacting the semiconductor material, thereby eliminating the harmful effect of solder running up the flanks while maintaining the electrical connection function.
Solution Approach 2:
The chip structure is segmented by introducing trenches or cavities between adjacent chips, which are then filled with insulating material. This segmentation creates isolated regions that prevent solder from spreading across chip boundaries and contacting semiconductor flanks, thus preventing short-circuits.
2Reliability
If insulating material is deposited in trenches or cavities, then solder is prevented from contacting semiconductor flanks, but additional manufacturing steps are required
Solution Approach 1:
The insulating material is deposited in the trenches or cavities before the final chip separation step. This preliminary action ensures that the protective barrier is in place before chips are divided, simplifying the overall process by combining protection and separation in a coordinated sequence rather than requiring post-separation protection measures.
Solution Approach 2:
The formation of trenches/cavities, deposition of insulating material, and chip separation operations are merged into an integrated manufacturing sequence. The insulating material serves dual purposes: it protects against solder contamination and acts as a cutting guide or support during separation, reducing the need for additional standalone process steps.
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 method effectively prevents solder from contacting the semiconductor flanks, thereby avoiding electrical performance degradation and ensuring reliable chip assembly.
Implementation Method 1
the insulating material is deposited by inkjet printing
Data Source
AI summary
The present description relates to a method of fabricating an electronic chip with passivated flanks from a semiconductor substrate, a first face of which is covered by connection areas, and in which chips are formed, the method comprising the following steps: forming trenches or cavities between the chips; depositing an insulating material in the trenches or cavities; and separating the chips by cutting at least the insulating material.