PCB Non-Plated Holes for Component Alignment and Storage Density
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Solution Overview
Problem
The arrangement of disk drives on backplanes in storage subsystems is hindered by mechanical through-hole locating pins, leading to reduced system storage capacity and performance, manufacturing challenges, and increased costs due to the need for additional components and airflow issues.
Innovation Solution
A printed circuit board design featuring a planar substrate with holes extending only partially through conductive layers, allowing mechanical locating pins to align components on one face while enabling electronic communication with components on the opposing face, thereby optimizing component placement and signal routing without disrupting conductive traces on the second face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical through-hole locating pins are used to align components on the backplane, then component alignment is achieved, but the pitch between locating pins must be increased reducing system storage capacity
Solution Approach 1:
The locating pin holes are segmented into two depth zones: a first depth that extends through all conductive layers to provide mechanical alignment, and a second greater depth that extends through the substrate to provide self-alignment. This segmentation allows the same hole structure to serve dual purposes without requiring increased pitch.
Solution Approach 2:
The solution adds a depth dimension to the locating pin holes, creating a three-dimensional structure with different functional zones at different depths. The first depth provides mechanical alignment function while the second depth provides self-alignment function, resolving the contradiction between alignment precision and storage capacity.
2Manufacturing precision
If mechanical through-hole locating pins extend through the entire substrate, then component alignment is achieved, but conductive traces on the second face are disrupted
Solution Approach 1:
The hole depth is segmented into two distinct zones: a first depth that stops at the conductive layers to maintain trace integrity, and a second depth that continues through the substrate for self-alignment. This segmentation allows the hole to provide mechanical alignment without disrupting the conductive traces on the second face.
Solution Approach 2:
Different regions of the hole serve different functions: the upper portion (first depth) provides mechanical alignment while the lower portion (second depth) provides self-alignment. The conductive layers in the middle region maintain their integrity by being bypassed rather than penetrated, preserving trace reliability.
3Adaptability or versatility
If additional daughter boards and mounting hardware are added to accommodate components, then component placement flexibility is improved, but system cost and packaging complexity increase
Solution Approach 1:
The two-depth locating pin holes serve multiple functions: mechanical alignment, self-alignment, and maintaining conductive trace integrity. This multi-functionality eliminates the need for separate daughter boards and mounting hardware, reducing packaging complexity while maintaining component placement flexibility.
Data Source
AI summary
A printed circuit board having one or more holes that are controllably drilled to extend into the printed circuit board substrate to a predetermined depth intermediate first and second faces. A mechanical locating pin is received into each of the one or more holes to mechanically align a first component for electronically interfacing with the printed circuit board substrate. A second component is installed on the second face directly opposite of the one or more holes such that the second component is in electronic communication with conductive traces or interconnects formed on the second face directly opposite of the hole.