PCB Dummy Pad Layout for Reflow Bending Reliability
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Solution Overview
Problem
The challenge is to maintain a secure electrical connection between electronic components and substrates during the reflow process, which can cause substrates to bend, leading to potential short circuits and performance issues.
Innovation Solution
A printed circuit board (PCB) assembly with a dummy pad is introduced to prevent solder cream from being exposed or displaced, thereby maintaining the connection between electronic components and substrates even when the substrate bends during the reflow process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflow process is used to heat and melt solder paste for mounting electronic components, then the electronic components can be securely soldered onto the substrate, but the substrate may bend during heating, causing solder cream to be exposed or displaced and leading to short circuits
Solution Approach 1:
A dummy pad is introduced as an intermediary element between the solder cream and the substrate. The dummy pad absorbs excess solder cream and prevents it from being exposed or displaced due to substrate bending during the reflow process, thereby maintaining connection reliability without interfering with the actual soldering function.
Solution Approach 2:
The dummy pad is pre-positioned around the connection pad before the soldering process. This preliminary arrangement ensures that when substrate bending occurs during reflow, the solder cream has already been contained and distributed by the dummy pad, preventing short circuits before they can occur.
2Reliability
If solder paste is applied to mount electronic components on the substrate, then secure electrical connection is achieved, but substrate bending during reflow may cause solder ball escape or displacement leading to short circuits
Solution Approach 1:
The dummy pad serves as a mediator that captures and retains solder balls that might otherwise escape during substrate bending. It provides a designated area for excess solder material, preventing short circuits between adjacent components while maintaining the electrical connection function.
3Ease of manufacture
If the substrate is heated during the reflow process to melt solder paste, then soldering is completed, but the heating process causes substrate bending and potential short circuits
Solution Approach 1:
The dummy pad extracts or separates the function of accommodating excess solder material from the connection pad itself. This allows the connection pad to maintain its precise dimensional requirements for electrical connection, while the dummy pad absorbs the stress and deformation caused by substrate bending during heating.
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
The use of a dummy pad effectively prevents short circuits and ensures reliable electrical performance by distributing soldering material and securing the connection between components and substrates, even under bending conditions.
Implementation Method 1
use a reflow process to heat and melt the solder paste
Implementation Method 2
heat and melt the solder paste
Implementation Method 3
mounting the electronic component on the PCB, by soldering the plurality of contact points to the plurality of pads
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A printed circuit board (PCB) assembly according to an embodiment may comprise a PCB including a plurality of pads and a dummy pad and an electronic component including a plurality of contact points disposed on a bottom side of the electronic component, and the electronic component mounted on the PCB by soldering the plurality of contact points to the plurality of pads. The dummy pad, provided on the PCB, may have an elongated portion spaced apart from an outer edge of the electronic component.