Trace Embedded Probe Device for High-Frequency Testing
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Solution Overview
Problem
Conventional membrane probe cards face challenges in controlling trace widths and thicknesses, leading to impedance mismatching and surface roughness issues, which affect high-frequency signal transmission and fine pitch requirements.
Innovation Solution
A trace embedded probe device with a circuit board featuring recesses and conductive vias formed by laser drilling, allowing for precise control of trace positions, widths, and thicknesses, using the original copper layer as the grounding layer and electroplating for trace formation, and grinding to achieve flush surfaces, with oxidation-resistant layers to prevent copper oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography process is used to form traces, then copper layers can be formed with protective coating, but trace widths and thicknesses cannot be precisely controlled and surface becomes rough
Solution Approach 1:
The patent replaces the photolithography process with a laser drilling process to form through-holes and recesses. This substitution enables precise control of trace dimensions and smooth surfaces by using laser energy to directly ablate material according to predetermined patterns, eliminating the roughness and dimensional control issues inherent in photolithography
Solution Approach 2:
The patent changes the manufacturing parameters by using laser drilling with controlled depth and positioning to create recesses of specific depths. By adjusting laser parameters (power, speed, pulse duration), the trace width, thickness, and surface smoothness can be precisely controlled, directly addressing the dimensional control problem
2Reliability
If protective layer is applied on copper traces, then oxidation is prevented, but high-frequency signal transmission is degraded due to skin effect
Solution Approach 1:
The patent applies different treatments to different parts of the copper structure. The trace surfaces are left exposed and smooth to minimize skin effect and maximize high-frequency conductivity, while the recesses and non-critical areas can have protective coatings applied. This localized differentiation allows simultaneous optimization of both electrical performance and oxidation resistance
Solution Approach 2:
The patent performs laser drilling and surface smoothing before any protective coating is applied. By preparing the copper surface in advance with precise dimensional control and smooth finish, the subsequent protective layer can be applied selectively or omitted from critical signal paths, preventing oxidation only where necessary without compromising high-frequency performance
3Manufacturing precision
If conventional electroplating is used, then copper layers are formed, but trace thickness is not uniformly controlled and fine pitch requirements cannot be met
Solution Approach 1:
The patent replaces conventional electroplating with laser drilling and recess formation followed by controlled copper deposition. This approach provides uniform trace thickness by precisely controlling the recess depth and copper fill amount, enabling fine pitch applications where uniformity is critical. The process simplifies the layer structure by eliminating the need for multiple electroplating stages
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
Enables the formation of thin copper traces with controlled surface roughness, facilitating fine pitch requirements and high-frequency testing by adjusting the insulating layer thickness, thereby improving impedance matching and signal conductivity.
Implementation Method 1
The first and second recesses and through holes can be formed by laser drilling
Implementation Method 2
The trace main bodies of the two grounding traces, the trace main body of the signal trace and the conductive layers of the conductive vias can be formed by electroplating at the same time
Implementation Method 3
the trace main bodies of the grounding traces and the trace main body of the signal trace can be processed by grinding to become flush in elevation with the upper surface of the insulating layer unit
Data Source
AI summary
A trace embedded probe device includes a circuit board including an insulating layer unit whose upper surface has first recesses and a second recess located therebetween, grounding traces and a signal trace whose trace main bodies are disposed in the recesses respectively and flush in elevation with the upper surface, and a grounding layer disposed on a lower surface of the insulating layer unit and connected with the grounding traces by conductive vias penetrating through the first recesses and the lower surface and provided therein with conductive layers. The trace main bodies, grounding layer and conductive layers are made of a same metal material. Probes are disposed on the grounding and signal traces respectively. The probe device is easy in control of distance, width, thickness and surface roughness of the traces, and beneficial to achieve the requirements of thin copper traces, fine pitch and high frequency testing.