Linear Applications Engineer at Texas Instruments tackles printed circuit
board (PCB) solder flux issues that affect circuit functionality in a recent
blog entry. When troubleshooting non-functional or poorly performing circuits,
engineers often run simulations or other analyses that consider the circuit at
the schematic level. If these methods fail to resolve the issue, even the best
engineer might be left feeling stumped, frustrated, or confused. I've felt this
pain myself. To prevent you from reaching a similar dead end, I present to you
one simple, but crucial, tip: keep it clean!
What do I mean by this? Well, some materials used during the printed circuit board (PCB) assembly or modification process can cause major issues in circuit functionality if the PCB is not properly cleaned. One of the most common culprits of this phenomenon is solder flux!
Solder flux is a chemical agent used to facilitate the soldering of components to a PCB. Unfortunately, if not removed after soldering, flux can also deteriorate the surface insulation resistance of the PCB – wreaking havoc on the performance of your circuit in the process!
As you can see in Figure 3, the solder flux contamination had a drastic impact on the behavior of the bridge sensor output! With no cleaning and hand cleaning, the bridge sensor voltage never reached its expected voltage of roughly VREF/2, even after an hour of settling time. The non-cleaned board also exhibited a large amount of external noise pickup. After cleaning it in the ultrasonic bath and allowing it to fully dry, the bridge sensor voltage was rock-solid.
In summary, improper cleaning of solder flux can cause major performance degradation, especially in precision dc circuits. Remember to use an ultrasonic bath for final cleaning of all hand-assembled or reworked PCBs. After drying with an air compressor, bake assembled and cleaned PCBs at slightly elevated temperature to remove any residual moisture.This one simple tip of “keep it clean” should help you spend significantly less time troubleshooting and more time designing awesome precision circuits!
What do I mean by this? Well, some materials used during the printed circuit board (PCB) assembly or modification process can cause major issues in circuit functionality if the PCB is not properly cleaned. One of the most common culprits of this phenomenon is solder flux!
Solder flux is a chemical agent used to facilitate the soldering of components to a PCB. Unfortunately, if not removed after soldering, flux can also deteriorate the surface insulation resistance of the PCB – wreaking havoc on the performance of your circuit in the process!
As you can see in Figure 3, the solder flux contamination had a drastic impact on the behavior of the bridge sensor output! With no cleaning and hand cleaning, the bridge sensor voltage never reached its expected voltage of roughly VREF/2, even after an hour of settling time. The non-cleaned board also exhibited a large amount of external noise pickup. After cleaning it in the ultrasonic bath and allowing it to fully dry, the bridge sensor voltage was rock-solid.
In summary, improper cleaning of solder flux can cause major performance degradation, especially in precision dc circuits. Remember to use an ultrasonic bath for final cleaning of all hand-assembled or reworked PCBs. After drying with an air compressor, bake assembled and cleaned PCBs at slightly elevated temperature to remove any residual moisture.This one simple tip of “keep it clean” should help you spend significantly less time troubleshooting and more time designing awesome precision circuits!
评论
发表评论