Alignment Jig for Passive SMD Stacking
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Solution Overview
Problem
Current high-throughput pick-and-place machines lack the precision to accurately stack optical components with tight tolerances, leading to increased manufacturing costs and lower yields due to accumulation of placement errors from machine and component tolerances, necessitating active alignment techniques that are slow and costly.
Innovation Solution
A method using a precise mechanical alignment jig with reference features to align surface-mount devices (SMDs) on a substrate, allowing for passive alignment without active optical testing, by mating the jig's boundary features with the SMDs' interface features to reduce placement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-throughput pick-and-place machines are used for placing surface mount devices, then productivity is improved, but manufacturing precision deteriorates due to placement tolerance errors accumulating when stacking multiple components
Solution Approach 1:
A mechanical alignment jig is introduced as an intermediary tool between the placement machine and the components being stacked. The jig provides fixed mechanical reference features (sides, corners, edges) that define precise registration relationships, allowing components to be placed relative to the jig's mechanical structure rather than relying solely on the placement machine's coordinate system. This intermediary mechanical reference structure enables tight tolerance stacking while maintaining high throughput placement capabilities.
2Manufacturing precision
If active alignment techniques are used to achieve tight tolerance alignment, then manufacturing precision is improved, but productivity deteriorates due to slow testing and alignment processes
Solution Approach 1:
The alignment jig is pre-manufactured with precisely machined mechanical reference features (sides, corners, edges) that establish fixed registration relationships before the placement process begins. These pre-established mechanical references eliminate the need for active alignment testing during production, as the precision is built into the jig's mechanical structure in advance. This preliminary preparation of reference features enables both high precision and high speed placement.
3Manufacturing precision
If highly accurate placement equipment is used to reduce placement tolerance errors, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The mechanical alignment jig serves as a simple intermediary device that provides fixed registration references without requiring complex active alignment systems. The jig's precision comes from its mechanical construction (machined sides, corners, edges) rather than complex sensors, actuators, or control systems. This simple mechanical intermediary can be used with standard high-throughput placement equipment, avoiding the need for expensive highly accurate placement machines while still achieving tight tolerance stacking.
Data Source
AI summary
A method is provided for assembling a stack of surface-mount devices (SMDs) on a substrate. The method provides a substrate, die, or printed circuit board (PCB) with a top surface having a landing pad and a first reference feature. An alignment jig is placed overlying the substrate top surface. The alignment jig second reference feature is aligned with respect to the substrate first reference feature. A first SMD is placed overlying the substrate landing pad. The first SMD third reference feature is aligned with respect to the alignment jig second reference feature. A second SMD is placed overlying the substrate top surface. Then, the alignment jig first boundary feature is mated with the second SMD second boundary feature. In response to the mating, the second SMD first interface is aligned over an underlying SMD active element.