Encapsulation Process for Hotbar Soldering Small PCBs
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Solution Overview
Problem
The hot bar soldering method is ineffective for small substrates as it causes warping and potential damage due to applied force, and can also damage nearby components with liquid or chemical exposure during the soldering process.
Innovation Solution
A method involving the application of a first protective layer over components on a PCB, followed by a second layer forming a level surface, allowing for soldering without direct substrate support, using a metallic element to clamp and heat the wire against a terminal, with the second layer resisting compression forces during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hot bar soldering is used on small substrates, then wire connection is achieved, but substrate warping and damage occur due to applied force
Solution Approach 1:
A support structure is introduced as an intermediary element between the hot bar and the substrate. This support structure receives the clamping force from the hot bar and transfers it to the fixture, preventing direct force application to the substrate and thereby avoiding substrate warping and damage while still enabling wire connection.
2Productivity
If hot bar soldering is performed on small substrates, then soldering process is completed, but components are damaged due to force and chemical exposure
Solution Approach 1:
The support structure acts as a protective intermediary that shields components from the clamping force of the hot bar. Additionally, the fixture provides a controlled environment that prevents flux and other chemicals from reaching and damaging components, thus maintaining soldering efficiency while eliminating harmful effects on components.
Solution Approach 2:
The support structure is positioned in advance to counteract the potential harmful effects of the hot bar process. By being in place before soldering begins, it preemptively blocks the transmission of force and chemicals to vulnerable components, preventing damage before it can occur.
3Area of stationary object
If substrate footprint is reduced for compact devices, then device size is minimized, but hot bar soldering becomes ineffective due to lack of support area
Solution Approach 1:
The solution moves the support function from the substrate plane to a vertical dimension by introducing a support structure that extends upward from the substrate. This allows the substrate to remain small in footprint while the support structure provides the necessary clamping surface area for effective hot bar soldering.
Solution Approach 2:
The system is segmented into distinct functional elements: the small substrate for mounting components, the support structure for providing mechanical support and clamping surface, and the fixture for overall positioning. This segmentation allows each element to be optimized independently, enabling small substrate footprint while maintaining soldering effectiveness through the dedicated support structure.
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
Enables secure wire connection to small substrates without damaging the substrate or components, maintaining structural compliance and preventing moisture ingress, while allowing for efficient assembly processes.
Implementation Method 1
heating the metallic element to melt a solder element positioned between the wire and the terminal
Implementation Method 2
melt a solder element positioned between the wire and the terminal
Implementation Method 3
the second layer is free of compression during an assembly process of the connector
Data Source
AI summary
A method for connecting or terminating wires to a printed circuit is disclosed. The method includes applying layers, such as a first layer and a second layer, to the printed circuit. The first layer is applied over several active components on the printed circuit, and provides a sealant against ingress of contaminants in the active components. The second layer is a rigid layer applied over the first layer. When the printed circuit is placed in a fixture, a metallic element, such as a thermode or hot bar, presses against the wires to hold the wires against several terminals on the printed circuit. The metallic element is heated to melt solder between the wires and the terminals. The second layer is configured to resist compressive forces from the metallic element and the fixture, such that the printed circuit and the active components are not damaged during the connection process.