Any tips for 4-layer boards?

[Byte_Butcher]

Outside of reading temperatures, that is? Just seems like a pretty beefy processor to read/display temperatures, so am merely curious.

Nahhh, you're missing the point!
It's not about displaying temperature.... It's a learning platform!
(that photo looks like it was a learning test for the MCP9800)

It's a board that holds a $3 PIC that has lots of I/O .
It has space for additional EEPROM if you feel like doing some data logging. It's got provisions for a DS1302 RTC if you need real time (to go with your data logging, or whatever?) (if you don't need that junk, don't load it)

It's got a connector to connect to an LCD display so you can... display stuff.
It's got an onboard MOSFET to control the brightness of the LCD backlight.

It's got all the excess I/O ins brought out where they can be used to play with all kinds of sensors or... stuff.

That board is not just about reading/displaying temperature. It's useful for all kinds of tasks!

That circuit board, fully loaded with all the options RTC, EEPROM, Onboard voltage regulator, LCD connector, etc costs about $15.

It's a learning tool for a PIC. What would you like to learn today?



steve

[TinkersALot]

Before anything else: Congratulations and Nice Job! This does look like it was a great learning experience -- especially with regard to re-arranging some parts and getting it to route into two layers. Interesting thread to read as well.

Don't mean to be thick-skulled about the purpose of your efforts. It is a neat board and project.

[Byte_Butcher]

Before anything else: Congratulations and Nice Job! This does look like it was a great learning experience -- especially with regard to re-arranging some parts and getting it to route into two layers.

It was actually a very good learning experience for me.
One of the best things I got from it was learning to use the "rats nest" feature on my PCB software.
The Rats Nest always freaked me out so I left it turned off.
After reading the tutorial that Robert posted the link to, I went ahead and turned the rats nest on... and learned to use it.
It really DOES help a lot in getting the parts laid out better and minimizing the amount of traces that have to wander all the way across the board.

Anyway, I should have boards here by the end of next week to test.
Hopefully there aren't too many mistakes...


steve

[Byte_Butcher]

UPS brought my boards yesterday!
I think I'm starting to really enjoy working with surface mount devices...
There's a certain pleasure in being able to put 63 parts (only 61 loaded in this photo), plus room for connections to the outside world (LCD display, sensors, power, etc) on only 4.5 square inches (29 sq cm) of real estate.

I loaded it up and ran it through the oven last night. Dunno if it WORKS yet, but it *looks* OK so far.



Here's a close up of the solder job. It's hard to resist the temptation to put too much solder on the pads. Just the tiniest bit is plenty. These look pretty good.



Big fun!

steve

[rsocor01]

Very nice!!!

Where did you buy your stencil from?

Robert

[Byte_Butcher]

Mmmm... if you mean a solder paste stencil, I've never used one. Yet...

For the small runs of boards I do, I apply paste by hand with a pointy tool under a magnifying lens. It took me less than 10 minutes to apply solder paste to all the pads on that board. (that includes going to the fridge and back for another beer). I'm hoping to be doing some larger runs of boards soon, so paste masks will become a necessity for me sooner or later (I hope).

I'd love to hear folks experiences with getting stencils made (cheaply)...


steve

[dhouston]

I've done them manually as you do and I've used a stencil. The thickness of the stencil controls the amount of paste applied. The stencil is preferred but for small parts and small quantities I still use manual methods. Here's a good source for stencils.

• http://www.quickstencil.com/prototype-stencil-kit.aspx

I've also seen less expensive mylar stencils but have not tried them.

• http://www.pololu.com/catalog/product/446