Overmolded Interconnect Tab with Vertical Sidewalls for PCB Alignment
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Solution Overview
Problem
Surface mount technology (SMT) assembly processes for printed circuit boards (PCBs) face challenges with misalignment of weld tabs, leading to weak electrical connections and the inability to automate the laser welding process due to lateral movement of plastic matrices, which are prone to misalignment.
Innovation Solution
The integration of oversized, electrically conductive pads with substantially vertical sidewalls within a conformal insulating layer on the PCB, forming a mechanically repeatable connection point that guides and secures interconnect devices, allowing for automated assembly and alignment despite some degree of misalignment during welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic matrix is used to embed terminal array, then cost-effective manufacturing is achieved, but lateral movement and misalignment occur making automation impossible
Solution Approach 1:
The patent applies preliminary action by pre-attaching the terminal array to the PCB substrate using conductive adhesive before the encapsulation process. This early fixation ensures precise positioning of the terminals relative to the substrate, eliminating lateral movement issues that would occur with post-encapsulation alignment. The conductive adhesive bonding occurs while the substrate is still accessible, allowing for precise placement before the encapsulant is molded over the assembly.
2Reliability
If traditional weld tab attachment is used, then electrical connection is achieved, but tip, tilt, or lateral movement causes misalignment and weak connections
Solution Approach 1:
The patent merges the terminal array attachment with the encapsulation process by simultaneously bonding the terminal array to the substrate and forming the encapsulant around it. The conductive adhesive bonds the terminals to the substrate while the encapsulant is molded, creating a unified structure where the encapsulant itself becomes part of the alignment and retention mechanism. This combined process eliminates separate alignment steps that would otherwise be needed to prevent tip, tilt, or lateral movement.
3Productivity
If automated laser welding equipment is used, then cost and repeatability are improved, but misalignment of terminals precludes its use
Solution Approach 1:
The patent applies preliminary action by pre-positioning and bonding the terminal array to the substrate before the welding process. The terminals are fixed in their precise locations using conductive adhesive and the encapsulation structure, creating a stable reference framework that enables automated laser welding equipment to operate without concern for misalignment. This preliminary fixation allows the welding process to be fully automated with consistent repeatability.
Data Source
AI summary
An integrated interconnect tab that provides a mechanically repeatable connection point to electrical components mounted on a printed circuit board. The integrated interconnect tab comprises a conductive pad surrounded by a vertical sidewall structure formed in an overmolded insulating layer. In one embodiment, a large pad accommodates connections to high-power circuit elements such as batteries and high-voltage capacitors. The sidewall structure helps align and guide the position of an interconnecting device such as a wire ribbon connector, facilitating automation of a subsequent attachment process. An automated method of making a PCB assembly having integrated interconnect tabs entails attaching circuit elements and interconnect tabs to a surface of a PCB substrate, encapsulating the attached components, and selectively machining the encapsulating layer to expose weld tabs, to form the vertical sidewall structure surrounding the tabs, and to create mechanical retention features to aid in welding.