Component side on Double Sided PBC

On 03/11/2012 06:53 PM, waveguide wrote:

I'm a new starter at pcb construction, but have used Eagle to successfuly design and make a single sided project board. I'm now designing a more complex double-sided board and have come up against a practical problem. The board will not have through hole plating, so I want to minimise soldering amongst the components.  I'm sure this is very commonly asked, but can I solder the components on either side? I have designed the board with a ground plane on both 'top' and 'bottom' layers. Looking at the pads, it will be far easier to manually solder all the components on the 'bottom' layer. There will be a few soldered connections necessary on the other side, but far fewer than if I put the components on the 'top' layer as defined by Eagle. Does it make any difference or am I missing a very obvious point?

Many thanks for you advice.

 

If you manually route you can control the connection side on part. You

can also just edit and fix things after an autoroute. It is also

possible to restrict traces from connecting to the top side of an IC by

putting a box around the IC on the Trestrict layer. Look at the layer

info on restrict and keepout

The other way is to use smd to make the board much smaller and order the

board for 1 off boards batchpcb.com was $10 + $2.50 per sq in for double

sided with solder mask and 2 sided silk screen.

Smd's are not much harder to hand solder. It just takes a fine temp

controlled tip, magnification and a steady hand. I have used two irons

to mount 0402 resistors and cap's. Just make sure the pads on the

package extend enough to get the tip on the pad and pin at the same time.

Paul R.

Thanks for your help and insights. I'd still like to know whether it's OK to simply 'relabel' the Top and Bottom layers.

Many thanks.

Hi

If a part is on the top layer and use wish it be on the bottom layer then you only need to mirror the part.

Hi

If a part is on the top layer, and you wish it be on the bottom layer, then you only need to mirror the part.

For simple stuff, for example capacitors and resistors that have two pins, yes you can.  For more complex things, for instance a TO-220 package, you can as long as you carefully think about pin orientation.  For complex parts, usually the answer is no.  Take for example a 6-pin DIP IC, if you were to route to the pins, the intent of these pins would only match the IC orientation in one way, and swapping it's side would mean the pins are wired incorrectly.  So I would say in general, the more complex your circuit the more likely it is that you will need to put the device on the side you designed it on.

But as others have said, just "mirror" the part and your orientation problems are solved.

Now I have got my head around this issue, I can see that some components will and some components won't simply 'swap sides'. I've experimented with the mirror tool and I've also learned that the routing system in Eagle will allow you to prioritise the way connections are made. I found by altering the top and bottom routing signifiers (or whatever they are), the bias of the connections can be altered between sides.

Many thanks for everyones' input.