Securing a pcb mount transformer

[00940]

I'm considering using a pcb mount 25VA Block flat transformer in a project and I'm currently drawing the package in Eagle.

There are 4 square holes at the corners of this transformer, 2.5mm wide (see picture attached). Am I supposed to use them to secure the transformer to the pcb (and how ?) or are the 8 solder pins sufficient ? A 25VA transformer is 450gr.

Thanks for any insight.

 

[rayma]

The soldered pins will normally be adequate. If the assembly will be shipped or dropped,
there should be pcb mounting bolts near the transformer on at least two sides, to reduce
the chance of board breakage. A thicker pcb for this than usual wouldn't be a bad idea either.
The four square holes are part of the mfg process.

 

[00940]

Thank you. I was already considering self tapping M3 screws or M2.5 screws and hot glue...

The pcb is quite small so I'm not overly worried about the pcb, rather the stress half a kg puts on the pins.

 

[nigelwright7557]

If those 4 square holes go all the way to the top of the transformer you could maybe drill out last bit and put four bolts through ?
Or maybe self tappers if holes dont go all the way to top.

 

[Mark Tillotson]

Self-tapping is probably what they are intended for, the datasheet doesn't say but does give them dimensions. I suspect standard M3 might grip the square 2.5mm holes well too, no idea if that was the intention.

 

[OlegSh]

I would not rely on solder pins alone due to the weight of the transformer. I used self tapping screws to secure similar transformers to the PCB and had no issues. You mount it only once anyways