If you don’t do so, the processes of fabrication and inspection become harder. As we pointed out earlier, the design of flexible electronics needs a significant amount of tolerance to cover films and stiffeners.Īs you consider cover films, don’t forget to take out the adhesive squeezing after the film dielectric lamination. The exposure of this circuitry can cause dimensional changes. Usually, flexible circuitry becomes evident during the processes of copper plating, pumice scrubbing, or etching. Such solder joints also create high-stress levels that may lead to mechanical fatigue failures. Some solder joints create electrical connections. However, keep in mind that there may be a concentration of mechanical stress at the potting area’s edge. Dab 5-minute epoxy on the edges of the accelerometer to do so. Potting helps prevent solder joints from flexing. You’ll probably need to pot the solder joints as part of the flex PCB soldering process. Given that there’s more stress concentration at each solder joint, it’s best to opt for a thicker stiffener, mainly if there’ll be active flexing on the accelerometer. Try placing a thicker stiffener close to the accelerometer’s solder joints to prevent solder joints from flexing. This stress concentration could cause fatigue and eventual failure of copper traces. Laminating the flex circuit’s backside helps reduce the concentration of stress at the edges of the accelerometer and connector. Here, you can use either carpet tape or double-back scotch tape, as well as an overhead transparency film. Make sure that the paste bridges onto the pad from the copper solder. If it does not, dispense some more solder paste.
Thoroughly clean the solder iron tip before quickly bringing it into contact with the accelerometer and substrate pad. Make sure that you use a small amount of solder paste onto the solder pad and accelerometer contact. Flux lowers the surface tension of the weld, ensuring that molten solder spreads and penetrates readily. It cleans the surface oxides, etches them, averts oxidation of copper after heating, and boosts the solder flow. In this technique, you will be using a flux pen during flex PCB soldering.
This section will look at how to solder the accelerometer using rosin-core solder and soldering iron. There are different techniques you can use when soldering the accelerometer. With practice, however, things should get more comfortable. The truth is soldering small contacts can be difficult. Many beginners find this part of the flex PCB soldering challenge. Stick to compact designs to shorten the thermal path. So what do you do during flex PCB soldering and assembly to ensure that a flexible circuit board dissipates heat well? Well, you need to go for components that have an exceptional surface-to-volume ratio. Failure to do so can lead to the outright destruction of the delicate circuitry in flexible PCBs. Engineers and designers must thus come up with a way to dissipate that heat. You may have heard that the cell phone battery exploded due to overheating.įlexible circuit boards are electrical conductors. Electrical appliances that do not release heat well can be dangerous. In all electrical devices, excessive heat is a legitimate cause for concern. Generally, it is best to stick to the minimum temperature to minimize the chances of damage due to exposure to heat.Ī flexible circuit board is considerably thin, so heat control is essential. The typical single-sided flex joint requires a reflow temperature of 330 – 400☌. It is best to seek guidance from a reputable PCB manufacturer where you do not know the proper reflow temperature profiles for flexible PCBs. Excessive heat during flex PCB soldering can lead to blistering and delamination. That is because these temperatures are likely to be much higher than flexible PCBs can tolerate. The general rule is that you should never use rigid PCB temperature profiles to reflow flex PCBs.