SESAME ELECTRONICS Pty Ltd

We can make you a PCB if you supply us with a file, or with a scan of a PCB. Email us for a quote. Contact Sesame

For these prototypes we do not need Gerber files, we derive a pdf of the artwork. We prefer artwork made by a PCB design program that can supply an ASCII drill file to control our drill. Programs we commonly handle include Protel99SE, Protel98, CircuitMaker/TraxMaker, AutoTrax, DipTrace, Eagle, EasyPCB, FreePCB, or Linux PCB, and others. We accept files that we can read by any downloadable program, just point us to it. We can also handle common computer formats, such as AutoCAD, CorelDraw, Paint, bmp, gif, tif, pdf, cdr etc., but for such files we have to drill by hand. In such cases you may prefer to do your own drilling. We can cope with practically any format. If we can print your artwork we can make your board.

If you have a file in ProtelDXP or some other advanced version of Protel, just 'save file as', or 'export as', Protel 2.8, and email us the resulting file.

Some tips for designers:

The dimensional restrictions below were developed to cope with the shortcomings of laser printers, used in our production of copper-only prototypes. Our factory can cope with finer details, as listed above, but for our copper-only prototypes please follow these guidelines.

Show boundary of board, or corner markers.

Show filename on copper layer.

Tracks should all be at 90 deg or 45 deg, other angles look bad.

Track widths: .020" for signals where possible, .012" where they pass between pads. .030" or wider for power and ground busses.

Minimum track width .012". If you've got the space, use 0.020", or .030".

Holes should be pin size + 0.2mm, smallest hole 0.8mm.

For single-sided boards, pads should be hole-size x 2.5. So smallest pad 0.8 x 2.5 = 2.0mm = .080". (Just remember 1mm is .040", 40 thousandths of an inch, or 40 thou). This leads to a simple rule:

In single-sided boards, for holes 0.8mm 0.9mm 1.0mm etc, use pads 80thou 90thou 100thou etc

For double-sided boards the pads can be smaller, hole size x 2.25. So smallest pad 0.8 x 2.25 = 1.8mm = .070".

So in double sided boards, for holes 0.8mm 0.9mm 1.0 etc, use pads 70thou 80thou 90thou etc

Use a grid of 0.100".

Don't use autoplace, place the components where you want them.

Place all pads, components, tracks on the grid where possible, otherwise on the half grid.

Align components horizontally and vertically.

Group together similar components where possible, such as resistors, caps, ICs. It looks better.

For DIL ICs use rounded rectangle pads .060" x .120". This will allow a .012" track to pass between pads and allow enough copper for soldering. If there are no tracks between pads you can use 0.070" pads and 0.8mm holes.

Minimum centre to centre spacing of .012" tracks: .050", if possible. Minimum clearance between tracks and pads .012".

If you need only one double-sided prototype, avoid through-hole plating by soldering component leads on both sides, or solder a matrix pin or wire. At the IC locations use turned pin machine sockets, they can be soldered on both sides. The trick is to leave the socket raised slightly when soldering the pins on the track side, then apply solder to the pin on the top side while heating the end of the pin. Keep it going until the solder flows around the pad at the top. Then apply the iron to the top pad. Of course if you're designing the board you can extend the bottom track clear of the IC and place a via to connect to the top track. We can make you one double-sided copper-only PCB with the holes not plated through cheaper than the through-plated version.

To protect the copper from tarnishing we generally leave the tracks and pads coated with resist. This avoids the cost of solder coating. It can be soldered through and left on, or removed with methylated spirits.

Each PCB should have a short number or name on it as an identifier, and this identifier should match the filename. If the drawing is amended, the filename should change, and the identifier on the board should be changed to match it. For example: ps01, ps02 etc. Keep the name to 8 letters or fewer.