Interleaved Via Arrays for High Density Multilayer Substrates
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Solution Overview
Problem
Current methods for forming high-density vias in multilayer substrates, such as PCBs, face limitations in achieving precise alignment and high density due to mechanical and laser drilling inaccuracies, resulting in low via density and thermal resistance, which hinders efficient thermal conductivity and electrical performance.
Innovation Solution
A method involving the formation of multiple arrays of holes with precise shifting and filling with conductive material to maximize via density, where each subsequent array is positioned between aligned holes of the previous array, allowing for increased packing density and improved thermal and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser drilling or mechanical drilling is used to form vias, then the drilling process is simple, but the via density is limited due to alignment precision and kerf size constraints
Solution Approach 1:
The via formation process is segmented into multiple drilling passes, where each pass creates a subset of via holes. By dividing the complete via array into multiple arrays that are offset from each other, each drilling pass can achieve precise alignment for its subset without being constrained by the kerf size or alignment precision limits of a single-pass drilling system. This segmentation allows the sum of multiple precise, lower-density arrays to achieve a higher overall density that overcomes the single-pass limitations.
2Temperature
If via density is increased to improve thermal conductivity, then thermal performance improves, but manufacturing capability is exceeded and alignment precision becomes unachievable
Solution Approach 1:
The high-density via array is segmented into multiple offset arrays, each drillable with standard precision. By creating several arrays with different positions (offset by half-pitch or other fractions), the system achieves a final via density that would be unattainable in a single pass, while maintaining alignment precision for each individual array through conventional drilling capabilities.
Solution Approach 2:
The solution moves from a single二维 (2D) drilling operation to a multi-dimensional approach by creating multiple arrays in the same plane with different positions. This dimensional multiplication of arrays allows the system to achieve higher density by combining multiple lower-density arrays, effectively adding a dimension of array multiplication to the drilling process.
3Productivity
If multiple arrays of holes are formed and filled to maximize via density, then thermal and electrical performance improve, but the manufacturing process complexity increases
Solution Approach 1:
The manufacturing process is segmented into multiple identical, repeatable steps: forming array 1, filling, forming array 2, filling, etc. Each step uses the same drilling and filling processes, just applied to different spatial locations. This segmentation into identical operations simplifies process control and tooling requirements compared to a single complex high-density drilling operation, as each segment can use standard equipment and procedures.
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 significantly increases via density, enhancing thermal conductivity and power transfer by interleaving arrays of holes and filling them with conductive material, overcoming the limitations of conventional drilling methods and achieving up to four times higher density, thus improving thermal and electrical performance.
Implementation Method 1
laser drilling technique is used to have the smallest via diameter with the maximum density of conductive vias
Implementation Method 2
The hole is then plated by a combination of electroless and electroplating processes with a conductive material such as a copper
Implementation Method 3
The hole is then plated by a combination of electroless and electroplating processes with a conductive material such as a copper
Data Source
Figure 1A~1H
Figure 2
Figure 3
AI summary
The invention relates to a method for manufacturing at least one array of conductive vias (100', 200', 300', 400') in a multilayer substrate (10), said substrate extending in a horizontal plane, said method comprising the steps of: a) forming a first array (100) of holes (101) in the substrate, b) filling the holes of the first array with an electrically conductive material in order to form a first array of conductive vias (100'); c) forming a second array (200, 300, 400) of holes (201, 301, 401) in the substrate, said second array being shifted from the first array along at least one direction in the horizontal plane in a manner that each hole (201, 301, 401) of the second array is positioned between two adjacent and aligned holes (101) of the first array (100) and; d) filling the holes of the second array with an electrically conductive material in order to form a second array of conductive vias (200', 300', 400'); e) repeating the steps c) and d) until that the array of conductive vias has reached the desired density of electrically conductive material with a maximum up to an area fully covered with electrically conductive material.