U.FL connectors – hints

This article expands on discussion at nanoVNA – that demo board and its U.FL connectors.

Before looking at the specifics of the Hirose U.FL connector, clean connectors work better and last longer. That should not be a revelation.

A can of IPA cleaner and a good air puffer are invaluable for cleaning connectors. The air puffer show  has a valve in the right hand end, it doesn’t suck the dirt and solvent out of the connector and blow it back like most cheap Chinese puffers, this one was harder to find and expensive ($10!).

A clean tooth brush and / or small paint brush may prove useful. I would not put cotton buds, Q-tips or anything with free lint into the connector unless you are sure you can remove any lint (like with a strong jet of clean oil free compressed air).

The Hirose U.FL connector is widely used on miniature equipment for connecting RF coax cables.

I use them in lots of projects, mainly 2.4GHz WiFi and 915MHz LoRa. Above is an example where a 2.4GHz WiFi antenna is attached to an ESP8266 module in a project providing telemetry of dam level sensed with a 4-20mA pressure transducer.

The connector above has been on and off a development board more than 30 times, it is still in good working order. Visually, it cannot be faulted. The connector is on a Molex 105262 915MHz antenna which cost about $6 a few years ago, it is inexpensive hardware, but good quality.

If you take care of quality connectors they last more than 30 cycles, but if you do not, they might not last 10 cycles.

Above is a close up of the U.FL connector, it has two ears for lifting it off the male part without cocking it sideways (which will damage the connector).

Above, a DIY tool hooked under the ears. It snuggly fits so it cannot disengage, and it does not prevent expansion of the spring rim which must expand to disengage the male part. Note that it does not apply force to the cable or its crimp.

Above, the other end of my DIY tool is ground flat and square to the shaft, and allows pressure to be applied to the connector whilst without allowing it to cock sideways (which will damage the connector). Note that it does not apply force to the cable or its crimp.

This tool can reach down into confined spaces, so there is almost never an excuse to not use it.

With all that, IMHO opinion the use of U.FL connectors on boards like that above does not make a lot of sense for several reasons, but if you have one, and take care with the connectors as discussed above, you should get good value from the thing.