using smd can I use both sides of the pcb to save room

I am working on a project that in the end will need to be rather small to work. I have been so far working with through hole parts and I am running out of room.

So my idea is can I use surface mount parts instead and use both sides of the board for components. If possible how difficult is this in eagle.

"mirror" puts the part on the other side of the board.
Then use blue lines for traces, and vias to connect to the other side.

TRy to keep all the thru hole parts and connectors on one side.


Provided the smd parts can handle any power requirements, sure. A 0603 resistor takes up a lot less room than a 1/4W axial lead resistor, BUT, that axial lead resistor sure can bridge over traces a lot better. Also, getting down to 0402 might 'look' easy enough to deal with, but rest assured they can be challenging, especially if in close proximity to other parts. A hot air rework station is a must, along with ordering several spares of tiny components that will simply vanish as you try to solder them, or even unpackage them from the tape.

Thanks Guys,

I am building this circuit (some of you have seen this before), I have it working with through hole parts I want to make sure I order the correct smd parts

I'm doing some shopping now I am planning on replacing a through hole 512-moc3162M with a 512-MOC3063SR2M there is a 512-MOC3163SM that is almost twice the price but I couldn't find a difference I'll link the datasheets if someone is interested in finding out the difference.

moc 3xxx datasheet

I am replacing a mac 15-6 400v triac with a T850-6G I'll give links to both datasheets for comparison.

MAC 15-6


I am going to go through and pick out the other parts resistors and caps and I'll post for inspection. as Tinman said make sure they are just as capable

BTW this triac I beleive says snubber less does this mean I don't need the snubber in the above circuit this would save me even more room???????

Will it work as good????

The below links are to the datasheets

I am thinking this for the 360 ohm KTR10EZPF3600

360 ohm resistor

and for the .01 uf capacitor SMDTJ02100VA00MR00

.01 uf Capacitor

and finally the 39 ohm resistor RT0402FRE0739RL

39 ohm resistor

I guess we will go with no news is good news :).

I checked all the parts were rated over 400 volts AC.

I don't exactly know resistor packages but 0805 seems to be a bit on the large end but I believe well smaller then it needs to be especially with both sides of the board available and like tinman13kup was saying if they are too small they may become difficult to handle.

After doing some closer checking the capacitor is pretty big. I chose another rated at 250 VAC but much smaller (still pretty big) -- CB042K0103KBC by AVX

.01 capacitor datasheet

After more checking my 39 ohm was not rated above 60V so I have changed to a ERJ-P06J390V by panasonic -- 0805.

39 ohm datasheet

Oh I checked into a rework station I found a couple between $39 and $120 doesn't seem too unreasonable and watched the sparkfun video on using the device.

I am just not sure about the snubberless thing. So I am going to include the snubber circuit. There is nothing saying it can hurt and prototype circuit has one and works great.

Now I have to find these parts in an eagle library or we may be seeing a thread about creating eagle parts by scratch.

Search engine with all eagle libs

Thanks again all