How to solder a 2-layer board with no busses?

Peter Zomer <communitymanager@premierfarnell.com> wrote:

Hi everyone,

 

I'm a newby and this is my fist post here.

I have a question about layers but can't find the answer on the forum here.

 

The problem case:

 

I want to make a PCB of two layers, 1 and 16.

Because this PCB is etched by myself, the pads on both sides are not

initally connected to eachother (with busses is it called?)

Using the autorouter of Eagle, it will create tracks on both sides of the board.

But if I want to mount, let say, an IC socket, I can't reach the socket

pins on the top side of the board with my solder iron.

This pin has to be soldered, because some track is connected to that pin.

 

This problem can be solved in two ways I think.

1. Try to create a 1-layer board.

2. Use vias right next to the pads, so that you can create the needed

connection from top to bottom.

 

Both sollutions are not realy nice.

 

Are the ways to setup the autorouter to get what I want?

I assume there must be more poeple avout here that are facing the same problem...

The easy solution is to NOT use through hole ICs. Soldering smd's by hand

is easier than you think. I even prefer it over through hole. Many

connectors also come as smd.

Am 04.09.2011 20:44, schrieb Peter Zomer:

Hi everyone,

 

I'm a newby and this is my fist post here.

I have a question about layers but can't find the answer on the forum here.

 

The problem case:

 

I want to make a PCB of two layers, 1 and 16.

Because this PCB is etched by myself, the pads on both sides are not initally connected to eachother (with busses is it called?)

Using the autorouter of Eagle, it will create tracks on both sides of the board.

But if I want to mount, let say, an IC socket, I can't reach the socket pins on the top side of the board with my solder iron.

This pin has to be soldered, because some track is connected to that pin.

 

This problem can be solved in two ways I think.

1. Try to create a 1-layer board.

2. Use vias right next to the pads, so that you can create the needed connection from top to bottom.

 

Both sollutions are not realy nice.

 

Are the ways to setup the autorouter to get what I want?

I assume there must be more poeple avout here that are facing the same problem...

 

Hope to hear tou soon.

 

PeterZ

 

THT without vias is not easy. You can make "vias" yourself by drilling a

hole put a wire through it and solder it on both sides.

Another solution is to use precision sockets. They don't settle on the

pcb but leave about 1 mm distance. If you extend the top copper traces a

little to the outside of the sockets you are able to solder the sockets

on both sides, top and bottom and so create "vias".

Of course this means that you have to leave enough space between the

sockets to be able to reach the pins with the solder iron.

--

Mit freundlichen Grüßen / With best regards

Joern Paschedag

Am 04.09.2011 20:44, schrieb Peter Zomer:

Because this PCB is etched by myself, the pads on both sides are not initally connected to eachother (with busses is it called?)

A connection between board layers is called 'via'. There is even an

EAGLE command available with the same name and for exactly that purpose.

A 'bus' only exists in the schematics and is sort of a container for

several nets belonging together, e.g. DATA[0], DATA[1], DATA[2],...

But if I want to mount, let say, an IC socket, I can't reach the socket pins on the top side of the board with my solder iron.

That depends on the sockets you are using. Since the majority of our

boards is also not 'through-plated' (and has no connections between

layers), we are using so-called 'carrier sockets': These are just single

pins without plastic frame that are held together by a brass carrier.

After soldering (which works well on both sides), the carrier is

removed. That is the easiest solution, but those carrier sockets are not

exactly cheap...

2. Use vias right next to the pads, so that you can create the needed connection from top to bottom.

In order to do that, you can create rectangles around the IC pads in the

layer 'tRestrict' to prevent EAGLE from connecting these pads to the top

layer. Instead, vias will be automatically placed somewhere else.

Are the ways to setup the autorouter to get what I want?

Your problem doesn't only concern ICs, but also other components like

trimmers, large capacitors, etc.: You wouldn't want to have vias placed

BELOW, e.g., a large capacitor. Creating all tRestrict areas to prevent

the autorouter from connecting things to the top there is quite some

work, if you don't want single-sided boards. Therefore, it is probably a

good idea NOT to use the autorouter at all. It doesn't create nice

boards, anyway. If you need a purely digital board, the autorouter is

OK, but I advise against it for analog boards - the results look too

strange...

Andreas Weidner

1. If you are new to pcb manufacturing you probably do not need 2 layer boards.

2. Do not use autorouter. It takes time to learn manual routing, but it's worth it.

Hi guys, (I assume)

Realy thanks for all the replies that I got !

I was hoping that Eagle had such an automatic feature, but it has not...

So, back to basic now. I will start with a single layer now and I indead have to practice a lot with that manual routin command. At the end I will give a feeling that I 'made' the board all by my self.

Thanks again !

Peter