Chip Resistor Rounded Corners Prevent Dicing Chipping
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Solution Overview
Problem
Chip resistors produced by dicing saws often have angled corner portions that are prone to chipping, leading to poor appearance and potential short circuits when mounted, which hampers productivity and reliability.
Innovation Solution
A chip resistor design featuring a board with rounded intersection portions between the front surface, back surface, and side surfaces, covered by a resin film, and an insulative layer, which prevents chipping and protects the resistor and interconnection films from foreign matter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dicing saw is used to cut the material substrate, then the chip resistor can be divided into multiple insulative boards, but the corner portions become angled and are prone to chipping
Solution Approach 1:
The patent applies preliminary action by forming rounded corners on the insulative board before the dicing cut is made. This pre-rounding of corner portions prevents chipping during subsequent handling and mounting processes, while still allowing efficient dicing saw production to proceed
Solution Approach 2:
The patent applies spheroidality by replacing the sharp angled corners produced by conventional dicing with rounded corner portions having a specified radius of curvature. This curvature eliminates stress concentration points that would otherwise cause chipping, while maintaining compatibility with standard dicing saw manufacturing processes
2Ease of manufacture
If the corner portions are left angled after cutting, then the manufacturing process is simple, but the appearance is poor and chipping occurs
Solution Approach 1:
The rounded corner formation is performed as a preliminary step before final dicing, allowing the corner shaping to be done once on the entire substrate rather than requiring complex post-dicing operations on each individual chip
Solution Approach 2:
The patent changes the geometric parameter of the corner portions from sharp angles to rounded shapes with a specified radius. This parameter change improves appearance and chipping resistance while being implemented through standard manufacturing processes
3Reliability
If chipping occurs during mounting, then the chip resistor may short circuit or fail to mount, but preventing this requires additional protective measures
Solution Approach 1:
The rounded corner geometry is built into the insulative board structure before mounting occurs, providing inherent protection against chipping during handling and soldering processes without requiring additional protective coatings or structures
Solution Approach 2:
The rounded corner portions act as a form of structural cushioning by distributing mechanical stresses that would otherwise concentrate at sharp corners. This preemptive geometric design prevents chipping under mounting conditions without adding separate protective elements
Data Source
AI summary
A chip resistor includes: a board having a device formation surface, a back surface opposite from the device formation surface and side surfaces connecting the device formation surface to the back surface, a resistor portion provided on the device formation surface, a first connection electrode and a second connection electrode provided on the device formation surface and electrically connected to the resistor portion, and a resin film covering the device formation surface with the first connection electrode and the second connection electrode being exposed therefrom. Intersection portions of the board along which the back surface intersects the side surfaces each have a rounded shape.