Wiring Substrate Dicing via Groove Separation to Prevent Core Cracks
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Solution Overview
Problem
Existing dicing methods for packaging substrates often result in cracks at the cut surfaces of core substrates due to differences in linear expansion coefficients, leading to stress and potential breakage, especially when using brittle materials like glass substrates.
Innovation Solution
A method involving the formation of an adhesive layer and rim pattern on the core substrate, with separation grooves created by removing portions of the insulating layer to expose the core surface, allowing for precise cutting along smaller margins than the groove width, thereby minimizing stress and preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dicing blade is used to cut the metal layer formed on the core substrate, then the packaging substrate can be diced into predetermined sizes, but the dicing blade may clog which lowers cutting ability and develops cracks at the end faces of the core substrate
Solution Approach 1:
The invention divides the cutting process into multiple stages by introducing a groove formation step before the final dicing cut. The groove is formed first to separate the metal layer from the core substrate at the cut location, creating a clearance that prevents blade clogging during subsequent dicing operations. This segmentation of the cutting function resolves the contradiction between maintaining cutting efficiency and preventing cracks.
Solution Approach 2:
The groove formation is performed as a preliminary action before the actual dicing cut. By pre-forming the groove that removes material and creates spacing between the metal layer and core substrate, the path for the dicing blade is cleared in advance, preventing clogging and crack formation during the main cutting operation.
2Reliability
If the core substrate is made of brittle materials like glass to achieve good electrical properties, then electrical performance is improved, but cracks may occur in the core substrate due to stress from differential thermal expansion
Solution Approach 1:
The invention extracts or removes the metal layer at the groove location to create separation between the metal layer and the brittle core substrate. This removal creates a stress-relief zone that prevents stress concentration at the interface between materials with different thermal expansion coefficients, thereby preventing cracks in the glass core substrate while maintaining its excellent electrical properties.
Solution Approach 2:
The invention applies local quality by creating a groove with specific dimensions (width and depth) at strategic locations where the metal layer is removed to expose the core substrate. This localized modification provides stress relief precisely where thermal expansion differences would cause the most stress, while leaving the rest of the core substrate intact to maintain its electrical properties.
3Manufacturing precision
If separation grooves are formed by removing portions of the insulating layer to expose the core surface, then precise cutting margins are achieved, but additional processing steps are required
Solution Approach 1:
The invention merges multiple functions into the groove formation step: it removes the metal layer, exposes the core substrate, creates the separation groove, and defines the cutting margin all in one processing operation. This consolidation achieves precise cutting margins while minimizing the number of additional processing steps required.
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 method enables the formation of packaging substrates without cracks, enhancing reliability under varying temperature environments by spacing the core step away from insulating and wiring layers, reducing thermal stress and improving adhesion between layers.
Implementation Method 1
a step of exposing the core surface of the core substrate by dissolving and removing the rim pattern of the groove bottoms
Implementation Method 2
a step of forming separation grooves having respective groove bottoms where the rim pattern is exposed, by removing portions of the insulating layer laminated on the rim pattern
Data Source
AI summary
The method of dicing a wiring substrate that includes a core substrate having a front surface and a rear surface at least one of which is provided with an adhesive layer and a rim pattern thereon. The adhesive layer is provided with a laminate that has wiring layers and insulating layers, laminating. The rim pattern is provided with the insulating layers laminated thereon. The method includes steps of forming separation grooves by removing portions of the insulating layers laminated on the rim pattern to expose the rim pattern; exposing at least one of the front and rear surfaces of the core substrate by dissolving and removing the rim pattern of the groove bottoms; and dicing the core substrate exposed at groove bottoms, along cutting margins each being smaller than a groove width of each of the groove bottoms.