PCB Design Suggestion


#1

Hi,

I’m creating a board and planning to use this CP2102 board in it. I want to solder it directly into the board and not use header pins on it. Any suggestions is appreciated.

Thanks for the help


#2

It’s got plated through holes (PTH) for a 6-pin header, which is connecting it to the outside world.
If you’re not using straight header pins to solder it to a carrier-board with similar holes, how do you propose to mount it (physically and electrically)?
The PTHs will make a strong physical and electrical bond if soldered correctly.
Can’t see how you could do better than that with what you got there really.
Maybe cutting half through the PTHs and doing some sort of castellation with SMT, but I’m sure the pads on the underside aren’t made for that nor will it be as strong (the carrier board would have no holes then though, so yeah, possible)… personally I would then also put some epoxy or silicone glue under the board where the USB connector is to make it mechanically more robust (usb plug in/out is pretty hefty for ad-hoc-castellations).

Anyhow, why don’t you want to use the PTHs + soldered header pins in both boards?


#3

I’m trying to experiment without holes (PTH) or header pins to see if it will work. Was looking for ideas on how to solder the UART board to the carrier board as it does not have castellation. Agree with you that it need to be hold together with some sort of glue or epoxy.


#4

I would simply mount the connector and IC directly on your board and not bother with the daughter board.


#5

That doesn’t help if he hasn’t got the tools to work with those chips.


#6

Not sure I understand what you mean ‘mount the connector and IC directly’ ? can you show PCB like that please ?
Thanks


#7

He meant to include the chip and its needed parts directly into your design.

The only tools you need to solder these is a magnifying glass, lots of flux and a solder iron. And of course a steady hand and a bit of patience.
I regularly solder qfp64 packages without other tools. (A top illuminated microscope helps a lot to be honest. But it is doable with a good magnifying glass.)

The main thing i would change if i need to hand solder something like that is to increase the distance between the chip and the usb connector.


#8

Thanks for the clarification. As this is for experiment for now want to see how far I can use the PCB board as it is. No plan to just use the chip


#9

Is the back side of that board essentially flat, or does it have components on it - or even a heavy layer of solder plating? If so, that will create a gap that the solder connection must bridge. When you put a film of adhesive between this board and the motherboard, that will also create a gap to bridge. Under any circumstances it will be difficult to impossible to inspect the solder joint.

I have a somewhat dissenting opinion. I have no doubt that some - perhaps many - sharp-eyed young people can do this under a desk-mounted magnifier lamp. It’s beyond the capabilities of MY tri-focaled, superannuated, eyes. Even under the toolmaker’s microscope, this IC package - with its 0.5mm lead pitch - is at the limits of what I’m capable of reliably soldering.

Dale


#10

Just use through hole pads that line up with the USB board pads. Then use wire to solder through to the lower pcb.
You may need a bigger pad + hole for the USB socket mechanical ground pins.
And possibly glue to hold it all together.


#11

@kicaduser… what kind of experience do you got with ALL of this?
I see this essentially is your first topic with us here and I’m starting to doubt you have done anything like this before.

Have you designed a pcb with SMT devices on it yet?
Did you solder it by hand or have it made?
Do you KNOW how reflow soldering works?
What kind of equipment do you got at your disposal?
Soldering iron? What kind?
Magnifying glasses, microscope?
Have you any idea what kind of options exist to mount devices and boards to a carrier board?

You got 2 options here to permanently mount this USB/RS232 converter onto a carrier board to…

  1. use the through holes and solder it like a through hole device onto the carrier board, like every sane person would do it.
  1. cut/grind/sand the holes to make them castellations and try to use adequate pads on your carrier board and expect problematic mechanical stability down the road. This option comes only up, BECAUSE you don’t want to use version 1) - no sane person would do it for ‘just experimenting’.

Also, as we’re all here to use KiCAD to DESIGN and MAKE our own boards you could copy the layout on that board, get you the devices that you see on it and incorporate it into your own designed board that has everything else on it and solder it with a soldering iron or a reflow oven - no need for 1) or 2) up there.
But this doesn’t float your boat either - which means you’re stumped and we can’t help you - all the while your motivation totally escapes me.

But that’s exactly what KiCAD.info is about:

Look at the example for getting from an electronic design to a final assembly made by @ChrisGammell . This is what is meant by using the parts and not the board:

That’s it. There are no other sane options out there for what you asked. This is how far you can use the board you got there.

Also, if you got design problems or KiCAD unrelated questions we can surely address them here, but there is websites/fora/mailing lists/etc. which are geared for these kind of questions and have more users online at any moment to address them (=faster response).
Example would be:

KiCAD.info is about support and help around KiCAD software and related things mostly.


#12

Thanks a lot everyone for the kind answer. I will study it more and see my options. My experience is minimal at this stage so all comments given are appreciate. When I’m done will post some picture.

Cheers


#13

I usually just apply a bit of solder paste with a syringe and then pop it in the toaster oven. Occasionally I need a little wick if I overdid it with the paste. I also have one of those USB microscopes for inspection. Believe it or not I have more trouble getting the 0603 parts to not tombstone.

If this is a one-off experiment and you already have one of those boards, then I would use the through holes with a straight pin header and then place some double sided foam tape under the USB connector.