From: "Roger Hamlett"
Subject: Re: Making 2 Layer PCB's
X-Newsreader: Microsoft Outlook Express 5.50.4807.1700
Date: Fri, 17 Jan 2003 12:09:58 -0000
NNTP-Posting-Date: Fri, 17 Jan 2003 12:09:34 GMT
Organization: ntl Cablemodem News Service
"Shaun Davy" wrote in message
> Just wondering if any of u electronic genius's out there have ever made 2
> Layer PCBs at home.
> Am building a board at moment that can't finish routing on single layer
> cause of too many tracks so I guess I have to goto 2 layer board or work
> how to get protel to do single layer and get it to use wire links.
> I have no troubles with the etching part but how do I take care of what is
> usually the through hole plating bit. resistors and diodes etc I can
> both sides of the board but I have a 28 pin socket for the pic and a DB9
> DB25 PCB mount connector on the board. How do I get both sides of the
> to make contact with the pins??
> Any suggestion appreciated
There is a system on the market, called 'Copperset'. It is marketted by
Multicore (the solder people). It comprises tiny solder filled 'rivets',
that can be spread with a punch, to give a copper tube, through holes in a
board. It is designed for repairs on PCB holes, where the plating has been
damaged. It is a very slow and laborious process, but does allow the
creating of PTH holes for single boards. In general, you should change your
design 'rules' a little, to absolutely minimise the number of holes that
have to be 'plated' (using parts that can be soldered top and bottom of the
board where possible), then on the few remaining hole that have to be
plated, this system can be used. The rivets require a hole about 0.2mm
larger than the required final hole size (so you drill at 1mm, to make a
0.8mm plated hole). The complete system, has a set of different size
punches, and little hand drills designed to open out an existing hole by the
0.2mm needed, and a few thousand rivets.
Another alternative (depending on how accurate your drilling and etch resist
processes are), is to talk nicely to a PCB company, and have the holes
plated before you etch. What you do, is drill the board, and take it to a
PCB company, who can then put it through their plating bath. Generally this
will only cost a few cents/pence. Then you have to fill all the holes with
an etch resist, and coat the board with the photo resist material, and place
the tracking as normal. When you have finished, you have a normal plated
through hole board!.
Generally on the PIC, it should be possible to solder both sides of the
board (use 'turned pin' IC sockets, instead of the cheaper blade style
units). The DB9, and DB25, then become the only parts that may need holes to
be linked through.