Hello.
I’ve got a two-sided PCB that I’d like to make up. The problem is that there is a surface mount IC (the Freescale MC33887DH driver) which must connect with the remainder of the circuit.
The surface mount chip will be soldered to copper contacts on the top of the board, but the remaining traces are on the bottom of the board. How can I connect these is a good way?
Any ideas will be appreciated!
You need to use a via.
When routing, if you a mid-route and you change the routing layer from top to bottom, EAGLE will inset a via for you. Otherwise you can place vias where you like with the via button.
vias are easy but you could also try putting the SMD on the bottom of the board. use the flip tool - looks like this
When you’re routing a wire, you can also Shift+click to insert a via ‘on-the-go’ so to speak.
I’m slightly confused about how a via establishes an electrical connection between the copper surfaces of a double-sided copper clad PCB. My understanding is that a via is a hole in the board where the layers should be connected.
Is the idea to drill the hole then fill it with solder?
mrbit:
I’m slightly confused about how a via establishes an electrical connection between the copper surfaces of a double-sided copper clad PCB. My understanding is that a via is a hole in the board where the layers should be connected.Is the idea to drill the hole then fill it with solder?
Via’s are plated (after they are drilled) on a regular PCB. On home etched boards you would need a wire, solder filled, or a grommet (compressed) to connect the different sides.
This is one reason prototypes with a large amount of via’s are often outsourced to be made by a PCB company.
James L
Yeah, if you are making them at home, you can do double sided boards but it takes a little care. Here’s what I do:
during layout, I push as many traces as possible to one side - try to make a single sided board.
put SMDs on the solder side.
use through hole parts to pass signals between sides where possible. make sure you can solder both sides of any pin used for that
as a last resort, use vias.
do not place vias under components.
to make vias, I drill a hole and insert a piece of wire. I usually strip a length of 22 ga or greater solid core and thread it through all the via holes. Then solder both sides of each via. I use the excess wire to test the solder joints and then clip it flush. It’s actually pretty fast.
Like Philba, I try to avoid making double-sided boards at home… usually I’ll have one side be just ground plane to make it easier. Having a few wire jumpers on a single-sided board is easier than going double-sided usually. For professionally-made boards (eg BatchPDB), the holes are plated-through which makes it easier (I still try to minimize vias though).