Embedded Device Copper Plating Laser Via Hole Precision
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Solution Overview
Problem
The challenge is to prevent the deterioration of embedded device characteristics and ensure precise via hole formation in printed circuit boards, where glass frit in external electrodes absorbs laser energy, leading to processing depth issues and increased defect rates during copper plating.
Innovation Solution
The solution involves forming a multilayer embedded device with dielectric and internal electrode layers, external electrodes covered by first and second copper layers, where the first copper layers have a larger particle diameter than the second, reducing particle boundaries and erosion, thus enhancing reliability and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If glass frit is used in external electrodes, then the external electrodes can be formed, but the glass frit absorbs laser energy causing improper via hole processing depth
Solution Approach 1:
A copper plating layer is introduced as an intermediary substance between the glass frit-containing external electrode and the laser beam. This copper layer absorbs the laser energy instead of the glass frit, preventing the glass frit from interfering with via hole processing depth while still allowing the external electrode to function properly.
Solution Approach 2:
The harmful laser energy absorption property is extracted from the glass frit by introducing a dedicated copper plating layer that performs this function separately. This separates the electrode formation function (glass frit) from the laser energy absorption function (copper plating), resolving the conflict between ease of manufacture and manufacturing precision.
2Manufacturing precision
If copper plating is performed on external electrodes, then via hole processing is improved, but particle boundaries cause erosion and defects
Solution Approach 1:
The particle size parameter of the copper plating is changed by using larger powder particles (average diameter of 0.5 μm to 5 μm) for the first copper layer. This parameter change reduces the number of particle boundaries, thereby reducing erosion and defects while maintaining via hole processing precision.
Solution Approach 2:
Different copper layers are applied with different particle sizes to address different requirements: the first copper layer uses larger particles to reduce erosion and improve reliability, while the second copper layer uses smaller particles for other functional requirements. This local differentiation of material properties resolves the contradiction between manufacturing precision and reliability.
3Reliability
If thin copper layers are used, then erosion is reduced, but coverage and conductivity may be insufficient
Solution Approach 1:
The copper plating is segmented into multiple layers with different particle sizes: the first copper layer uses larger particles for erosion resistance, while the second copper layer uses smaller particles for better coverage and conductivity. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between reliability and manufacturing precision.
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 approach improves the moisture resistance and operational lifespan of the embedded device by limiting the thickness of the first copper layer to 0.1 μm to 4 μm, reducing defects and maintaining the integrity of the embedded device and printed circuit board characteristics.
Implementation Method 1
the first copper layers have a larger particle diameter than the second, reducing particle boundaries and erosion
Implementation Method 2
a component contained in the glass frit may absorb the energy of a laser beam at the time of performing laser processing to form a via hole in the board
Data Source
AI summary
An embedded device includes a multilayer body including dielectric layers and internal electrode layers interposed between adjacent dielectric layers; external electrodes disposed on external surfaces of the multilayer body to apply electric charges having different polarities to adjacent internal electrode layers, the external electrodes containing a conductive material; first copper layers disposed on external surfaces of the external electrodes to cover the external electrodes; and second copper layers disposed on the first copper layers to cover the first copper layers. An average particle diameter of powder particles of the first copper layers is greater than an average particle diameter of powder particles of the second copper layers.