Hello,I am designing a RF circuit (0.1-6GHz) with sp8t switch(HMC321ALP4E) and transfer switch(HMC427ALP3E) and I will have to use SMA connectors.My trace width is 0.38mm.I added my pcb SMA pictures below. The vertical one is must, I cant place it on edge, It has to be in the middle of circuit and there are many of them, so it is important for me.
My questions are,
1- What kind of SMA should I use for vertical type SMA? Through hole type or with no holes and just soldering it on pcb? How should I connect it to pcb, 5 holes or 4 holes? Which product do you recommend.2- Vertical pcb mount SMAs usually has large center pins, and my signal trace is 0.38mm. I think this will be a problem, will it be? What do you recommend
Currently these are what I am thinking, what do you say?
The vertical SMA you are considering is a surface mount part, this means mechanically it won't be as secure, and if you twist too hard you risk ripping the copper of the board. The through hole version will be better for mechanical stress, but there will be a stub (the part of the connector that goes through the board) if the trace is taken off the top layer. If you can use a through hole SMA but take the trace from the back side, then you avoid the stub and also get the mechanical stability.
My signal layer is at top layer, so correct me if I'm wrong please,
you are telling me that the problem is, the center pin is too long so it will come out of the pcb and will be in air? What if I let the SMA stay in air and just put the right amount into pcb.
So my ground layer is not at the bottom, it is a 4 layer pcb. If I place SMA at bottom layer(4. layer) My GND layer which is layer-2 wont be the ground anymore or will there be a problem?
And about gnd, I was thinking that i will let the layer-3 stay there and all the layer-1-2-3 will be connected to each other by the many vias. Is it okay to use layer-3 like this? Or should i just completely remove it or just use it as Vcc for mcu. (I will use an external eval board microprocessor)
Thank you SO much for your response. I dont have many people with knowledge you have so I am bothering you, sorry and thank you again.
Its not that it will be in the air, it will be that the signal will be connected to a trace, but the connector pin will continue through the board, making a stub. You are at fairly low frequencies, so it might not be a problem. Using the SMA connector that is surface mount will eliminate that stub.