Professional to include ready-made circuit boards on commercial products

[Urahara]

Hi

Am thinking of developing a small-time commercial product for a niche market and am in the process of designing the circuit. It's not a complicated one, and the size will easily fit into the palm of a person.

For subsystems like power (say 1.5V boost to 5VDC) or Bluetooth serial module, there seems to be quite a number of relatively inexpensive, ready-to-run circuit boards with soldered components easily available in the market. Am thinking of using these pre-made modules, soldering them to the my main PCB I am making for this project. Of course I can include these subsystems onto my main circuit board instead of using these pre-made modules. But as I am not producing a huge quantity, leveraging on these pre-made modules seem like a pretty cost-effective option.

Just wondering if such practices are considered normal or unprofessional for "small time" commercial products?

As you can probably tell, I am not an expert in the world of electronics. But thought I'll hear the opinions & advice of the learned and experienced folks in this forum.

Thanks!

 

[ClydeCrashKop]

I have seen numerous products with small circuit boards piggy-backed onto the main board. I say just treat it like a component. An LCD display module comes with its own circuit board and they are used as a unit.

 

[throbscottle]

It always amazes me that if I search for a particular IC on eBay, quite often modules are listed which are cheaper than the IC itself. So certainly cost effective. I take it you've found alibaba.com? Might be a good source.

 

[Urahara]

Thanks for the validation! Yup, those stuff on alibaba are really tempting!

Another question : How does one solder modules like this :

I am familiar with through-holes and smd pcb pads, but have not seen or work with this. What do you call such pads, and how do you solder them manually? Any links, info appreciated.

Thanks again!

 

[Urahara]

Think this might be clearer : I am talking abt those pads labelled J6.

 

[jpanhalt]

Linx Technologies has similar boards. They are not hard to do by hand. Just flow the solder under the board. Here is the description from Linx:

Here's the link: https://www.linxtechnologies.com/resources/data-guides/rxm-gps-fm.pdf
Look around page 36. It also describes automated assembly.

John

 

[Mike odom]

yes, jpan, that's what I was going to say. The ONLY place I've seen pads like this were Linx products, and they solder pretty easily. Other than the old LCC (leadless chip carriers) of the 80's... whatever happened to those?

 

[Urahara]

Found a video that shows how such a module can be soldered :

Btw, does anybody know where in Eagle library can I find this footprint :

 

[jpanhalt]

The link I gave to Linx showed its recommended footprint for the PCB (page 35). It does not include the castellations. Instead, it has regular rectangular/square SMD pads. What you seem to show is the board outline of the device you are using, not its recommended footprint.

You could make specially shaped "pads" in Eagle with the semi-circular indentations, but why? The castellations might make soldering and routing more difficult.

Directly to your question, I have not seen castellated footprints in Eagle. If they exist, your most likely place to find them are on the Eagle site in the additional libraries section.

If you need to make it yourself, an easy way would be to copy the footprint for almost any 16-pin, 1.5 mm SMD device and modify it to the correct width. You can also click on the pads in the package editor and change the size to whatever you want. If you want to make your own castellated pads, I would do it in that editor. That will save having to draw the whole package and get spacings correct.

John

 

[Urahara]

Thanks John! That was indeed the module footprint. Will try creating one within Eagle myself then.