PCB Tapered Metal Post Structure for Fine-Pitch Alignment
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Solution Overview
Problem
The increasing demand for higher density and finer pitches in electronic components, such as CPU and GPU cores, poses challenges in aligning connection members between chips and substrates, leading to defects like pad separation, short circuits, and reduced yield.
Innovation Solution
A printed circuit board design featuring a tapered metal post with a narrower upper surface than lower surface, which is manufactured by forming a pad, a protrusion, and then a metal post on the pad, covering the protrusion, to improve alignment and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional metal post with uniform width is used, then the manufacturing process is simple, but alignment precision deteriorates leading to defects
Solution Approach 1:
The metal post is designed with an asymmetric tapered structure where the upper width is smaller than the lower width. This asymmetric geometry provides a self-aligning feature that guides the connection member into proper position during assembly, thereby improving alignment precision without requiring complex external alignment mechanisms.
Solution Approach 2:
The invention transitions from a two-dimensional uniform cross-section metal post to a three-dimensional tapered structure. By introducing dimensional variation along the height of the metal post, the design enables self-alignment functionality that improves connection reliability while maintaining manufacturing feasibility through standard plating processes.
2Productivity
If the pitch of metal posts is reduced for higher density, then mounting density improves, but connection reliability deteriorates due to alignment difficulties
Solution Approach 1:
The tapered asymmetric structure of the metal post acts as a mechanical guide that compensates for reduced pitch spacing. The converging geometry provides natural alignment tolerance that prevents misalignment defects even when metal posts are closely spaced, enabling high-density mounting while maintaining connection reliability.
Solution Approach 2:
The tapered shape of the metal post provides a cushioning effect by gradually guiding the connection member into position. This geometric cushioning compensates for potential alignment errors before the final connection is made, preventing defects such as pad separation or short circuits that would otherwise occur at finer pitches.
3Reliability
If a tapered metal post with narrower upper surface is used, then alignment and connection reliability improve, but manufacturing complexity increases
Solution Approach 1:
The invention changes the geometric parameters of the metal post from a uniform cylindrical shape to a tapered shape with varying cross-sectional dimensions. This parameter change is achieved through controlled plating thickness variation, where the plating process is optimized to deposit different thicknesses at different heights, creating the tapered profile without requiring complex multi-step manufacturing.
Data Source
AI summary
The present disclosure relates to a printed circuit board including a first insulating layer, a pad disposed on an upper side of the first insulating layer, a protrusion disposed on the pad; and a metal post disposed on the pad and covering the protrusion, wherein the metal post has a tapered shape, such that a width of an upper surface of the metal post is smaller than a width of a lower surface of the metal post, and a method of manufacturing the printed circuit board.