Question First "SMD" project - NPL timecode receiver

Hi,

Just finished my first electronics project using surface mount components, those components are REALLY small !!

Project is a narrow band 60 KHZ receiver for NPL time code transmisions (MSF) and has provision for an external active aerial via a USB connector (excellent for DIY projects with cheap cables readily available).

Board is double sided with "vias" made from 0.028" copper wire rivets. Layout used Eagle 8.1.0 autorouter and "pcbgcode" to drive my SC420/2. Tool used was a 30degree milling bit with an end dimension of .075mm (.003").

Soldering of smd's uses a minute drop of printable solder paste applied with a sharpened cocktail stick to the mounting pads before placing the component. Soldered with 0.3mm pencil tip bit controlled at 370C - a really steady hand needed and components held in place with other end of aforementioned cocktail stick!!

And it works - cant be bad!!

Peter

Hi, good job. Can you tell me some parameters you use in pub-gcode?

Isolation > Min=?, Max=?,Step size=?

Etching Tool Size=?
Z Down=?

Thanks

Here is a PCB I made.
Isolation is approx. 0.2mm (8mil) wide, wire width 0.4mm (15mil).
Single pass, Minimum 0.0254mm (1mil)
Etch depth 0.2mm (8mil)
Z down 0.05mm (2mil)

Etching tool: VHM graver, 60 degrees:

www.sorotec.de/shop/Zerspanungswerkzeuge/sorotec-werkzeuge/1-8-werkzeuge/Gravurwerkzeuge/Gravierfraeser/VHM-Fr-sstichel-60-.html

I am using the PCB Autoleveler Plugin.

The LT2440 is a SSOP, resistors 0603 and 1206, rivets Bungard 0.6mm.
Looks a bit awful as I soldered the rivets that they don't corrode.

Hope that helps.

Made a mistake:
Etch depth 0.2mm (8mil) should read Etch Tool Diameter 0.2mm

Hi,

The parameters I use in Eagle 8.1 are :-

Default track width - 0.4mm (0.016")
Power Vcc & Gnd - 0.6mm (0.024")
General clearances - 0.3mm (0.012")

I usually rely on the autorouter for most of the layout, and afterwards adjust the occasional track where there is room to do so. Thermals are all adjusted to 0 or 90 degrees prior to a flood polygon for ground plane. Isolation here is set to 0.4mm (0.016"). and all orphans are retained.

In pcbgcode I used single pass with milling set to 0.125mm and spot drill to 0.25mm. Climb preference is set with a minimum of 0.05mm.

The router tool is a 3mm x 30degree carbide with a measured tip width of 0.075mm (0.003"). Using this with a Z depth of 0.43mm gives a minimum isolation of 0.3mm (0.012")using a single pass. Spindle set to 18000rpm

It is vital that backlash compensation is applied to both X and Y axes.

Pcb vias are made using bare copper wire 0.022" diam (24swg) in 0.7mm (0.028")holes. To fit, one end of the wire is bent at 90degrees and trimmed to about 0.5mm, then threaded though the board until bent part is flush with the surface. The protruding part on the other side is now bent sharply at 90 degrees and cut off to 0.5mm. Finally the "rivet" is flattened with a small punch against a steel backing plate then soldered both sides. Long explanation of a simple process!!!

"Rivets" fitted before soldering.