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Bridging During PCB Assembly

The technology that goes into electronic devices is continually getting smaller and more powerful. We’re cramming the electronics that used to live inside giant desktop towers into things you can strap onto your wrist. This trend towards miniaturization can be a boon for consumers, but it creates challenges for engineers and manufacturers that design and build the components that go into those devices. One of those challenges is solder bridging. Solder bridges occur when melted solder unintentionally connects two different nets of metal on a printed circuit board (PCB). While it might not sound dangerous, these small solder bridges can cause big problems like intermittent connections, false test results, or traces and component leads that burn through.

While it might seem counterintuitive, a lot of the time solder bridging occurs because we’re trying to do too much in too little space. The constant shrinking of package sizes forces original equipment manufacturers to compromise on design and layout, which can lead to issues that might not be evident in early prototypes but show up as defects in production.

Another common cause of solder bridging is not properly managing the reflow process. The recommended temperature profile and dwell times for the reflow process must be followed precisely to ensure that all of the solder paste is completely melted and flows onto the component leads and PCB pads. If not, solder bridges can form between the pad and the wire or pin.

Solder bridging can also occur because of contamination on the surface of the PCB. Dust, oil, moisture, and other contaminants can interfere with the wetting of the solder paste to the surface of the PCB. Thorough cleaning of the PCB prior to assembly can eliminate these contaminants and reduce the likelihood of solder bridging.

Solder Bridging During PCB Assembly

Finally, solder bridges can occur because of poor fiducial mark placement. These are precisely designed markers that you put into your PCB design to help the automated machinery that puts your parts on find them and align them correctly. If you don’t have control over the manufacturing of your PCB, it’s important to choose a contract manufacturer that prioritizes quality work.

In-process testing is testing that occurs throughout the production process to catch any defects, errors, or inconsistencies. This testing can be done using techniques such as visual inspection, automatic optical inspection (AOI), and X-ray inspection. Catching these issues early in the process allows engineering teams to correct them before they impact the quality and functionality of the finished product. In-process testing is an essential part of any pcba assembly operation.

Solder bridging during PCB assembly is a common issue that can occur during the soldering process. It happens when excess solder creates an unintended connection between two adjacent conductive elements on the PCB, causing a short circuit. This phenomenon can lead to malfunctions or even complete failure of the electronic device.

Several factors contribute to solder bridging, including the design of the PCB, the type of components being soldered, and the soldering technique used. Insufficient spacing between components or pads, incorrect solder paste deposition, improper temperature settings during reflow soldering, and excessive solder volume are among the primary causes.

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