SESAME ELECTRONICS Pty Ltd

Unit 1, 19 Bestic St. Rockdale NSW 2216 AUSTRALIA.

sesame@sesame.com.au
0434 781 191

Sesame Electronics on LED

We make Printed Circuit Boards.

  • Any artwork format
  • One or many
  • Bare boards, or with parts supplied, assembled and soldered
  • Single-sided, double sided, or multi-layered
  • We can design a PCB from a schematic circuit
  • Low prices
  • Hobbyists and businesses welcome

Fully-featured boards:

We can supply high quality PCBs in any quantity. We can handle any artwork from which we can extract RS-274X Gerber files. Programs we commonly handle include Protel99SE, Protel98, CircuitMaker/TraxMaker, AutoTrax, DipTrace, Eagle, EasyPCB, FreePCB, Linux PCB, Fritzing, Kicad, ExpressPCB. We can extract gerber files from ExpressPCB. We accept files that we can read by any downloadable program. The boards can have minimum track/space 6thou, smallest drill size 0.35mm, and multiple layers. They can have all the features, such as plated-through holes, solder masks, silkscreens, gold-plating etc. These are top quality boards. Delivery within two weeks. Email us for a quote..

We accept payment by direct deposit, or with credit card via PayPal. Paypal is a free internet bank through which you can pay anyone who has an e-mail address without telling them your credit card details. You only tell PayPal your credit card details when you register.

Copper-only prototypes:

As well as the fully-featured machine made boards above we can supply copper-only prototypes, single or double sided at a fraction of the cost. We hand etch the artwork and hand drill the holes. We leave the uv resist on the boards to protect the copper. It's better to solder through it, but it can be removed with metho.

For a prototype you don't need the overlay, you know where the parts go. As you are hand soldering you don't need solder masks, any excess solder can be removed with solderwick.

We can make such a PCB if you supply us with a file, or with a scan of a PCB. We can handle common computer formats, such as AutoCAD, CorelDraw, Paint, bmp, gif, tif, pdf, cdr etc. We make boards from Silicon Chip, or other electronic magazines, or from a print.

For such prototypes we don't need Gerber files, we make the boards from pdfs of the artwork. If we can print your artwork we can make your board.

We print the artwork at 2400dpi, and we project the pads onto crosshairs on the computer screen for accurate drilling.

Some suggestions for designers:

Align components horizontally and vertically.

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

Show the boundaries of the board.

Show the filename on a copper layer.

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

Handmade boards are best designed with larger tracks, clearances, and pads than machine made boards, as follows.

Track widths: Use .024" for normal signals, with .026" separation. This places them on a .050" grid. They can narrow to .012" where they pass between pads. Make the power and ground busses .030" or wider. Use minimum track widths and clearances .012".

Holes should be pin size + 0.2mm. Use holes in multiples of 0.1mm, smallest hole 0.8mm.

Pads should be hole-size x 2.25. It works out that a 0.8mm hole gets a 70thou pad, 0.9mm hole a 80thou pad, 1.0mm hole a 90thou pad, and so on.

Place all pads and components on the grid where possible. Use a grid of 0.050".

Minimum centre to centre spacing of .012" tracks: .025". Use .050" where possible.

For DIL ICs use 0.070" pads and 0.8mm holes. If there are tracks between pads you can use rounded rectangle pads .060" x .120". This will allow a .012" track to pass between pads and allow enough copper for hand soldering.

The PCB as a lid:

After testing a PCB, most people let it lie around exposed and unprotected until they get around to putting it in a box to try to display how the finished product would look. To do this they desolder those components that are to be accessed from the outside, and try to cut suitable holes in the box, joining these components to the board by soldering wires, then stick labels on the box. The result can look rather crude, except for the PCB, which is hidden from view.
An alternative way is to design the PCB as a lid, resulting in a better appearance and less work. The lid of the box is replaced with the PCB.
The project name, logos and component labels are made neatly by the PCB maker's component overlay, and the holes are cut by his CNC router. Those components that need to be accessible, the connectors, switches, buttons, LEDs etc are through-hole components on the top side, soldered to pads on the bottom layer as usual. The other components, transistors, ICs, capacitors etc are chosen as surface-mount components, and are soldered to the bottom layer. The PCB is then screwed to the box as a lid. No pins are exposed on the top. There is no wiring to do.

Assembled boards:

As well as the bare boards, we can supply and assemble the parts if required. For an assembly quote, email us a parts list, preferably in Excel spreadsheet form, with fields:

Component, Type, Value, Quantity, Digi-Key Part No, Manufacturers No.


The PIC Club

The PIC Club, a part of the the Sydney PC User Group, meets in Sydney 6pm-8pm on the second Tuesday of each month. We bring together professionals, hobbyists and beginners to discuss microprocessor project design and programming. Come and show your projects, or see some others. The next meeting is on Tuesday August 9, 1st Floor, Sydney Mechanics School of Arts, 280 Pitt Street, Sydney.

The following are highlights of the latest meeting. See previous meetings.

At the July meeting we saw how to make a solder paste stencil and a solder paste mask for PCBs by etching aluminium or copper sheet. It is good enough for small to medium quantities and much cheaper and quicker than buying in a laser cut stainless steel stencil. The procedure:
Spray paint with circuit lacquer one side of an aluminium sheet 4 mil thick.
Bond UV sensitive film to the other side.
Print the solder paste mask on a transparency.
Expose the film to UV light through the transparency, develop, and etch.
Remove the lacquer, and you have a stencil.
Apply vaseline to the PCB through the stencil then spray circuit lacquer over it.
Once dry, wash the vaseline off with methylated spirits, leaving a lacquer solder mask.
Apply solder paste through the stencil.
Place the components, and reflow by placing the board on a hot frypan.


Website by Neville Hoffman

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