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Vinyl film PCB technology


Film templates is most simple PCB production method. It have less resolution than laser printing, but does not require experiments with paper, toner and printing temperature. Film is cut on vinyl cutter, which available on market and costs from $150. Advantages are simplicity, high-quality production, low materials wasting. Disadvantages are low resolution and difficulties with small tracks details such as text.



Tracks should have vector contour, which can be made in vector editor or via raster tracing. The editor used should be able to export in cutter acceptable vector format: PostScript, DXF, DM/PL or HP/GL (aka PLT). Tracks image does not require flipping since it will be adhesed on copper face side up.

Cutter knife cannot draw lines too close due to mechanic limitations. Minimal tracks thickness is 0.7 mm, recommended - 1.0 mm. Pads sould be as large as possible. This method of production allows to put 0805 smd size parts on PCB, but minimal recommended size is 1206. You can also prefer to track connections with polygons instead of thin tracks. Unlike laser printed template, where there are polygon quality issues (toner flaking), vinyl film provides maximum polygons quality. Our PCB track images are vector contours and can be used in both laser and cutter technology PCB production. Flip image horizontally or vertically, if you are using laser printer.

Space between tracks should be large enough to prevent shorts circuits (whuch can ocurr due to adhesive blots between tracks). Minimal space is 0.5 mm, recommended is 1.0 mm. If your cutter is old, knife deviations are heavy and it can't provide even these limits, tighten screws and nuts in the knife drive. This will improve accuracy.

There is 3-5 mm frame around tracks image, it makes mounting easier and can be used as copper clad sheet cut marker after. Outline contour thickness of tracks group is 0.001-0.01 mm (depends on cutter firmware or driver) and then exported to cutter format. If your cutter comes with cut software, export to the format of software. Do not print image from your vector editor, this may cause distortions, notorious is knife offset ignorance. Typical knife offset is 0.5 mm (they have about 1 mm in diameter), and is set in software/firmware/driver properties. Ignored or set to zero, it leads to image edges distortion.

Polygraphic cutters with 60-120 cm width are not necessary. Images can be cut at home on small cutter, e. g. chinese DC240/DC330.



Make few copies until you improve your mounting skill. One day you will cut single image and adhese it to copper clad sheet without redo. If not, vinyl film is cheap. Oracal 641 series is best. For best adhesing, press on film with tampon or finger.

Remove unnecessary parts of image and cover with mounting film (transparent, it have numer 000). After adhesing, remove substrate paper and mount the film to copper. Removing unnecessary parts of image requires patience. Always examine film tracks with original tracks on image. If you had forget or removed some, copper in these places will be etched. Tracks, removed by mistake, can be cut separately without whole image. Just mount it in place. After mounting, transparent film is removed.



Requirements to copper surface are much lesser than for laser print. You can even sand it with thin finising paper only, paying no attention to fat removal and oxide cleaning. Just make surface flat enough, without significant pollutant spots.

Do not iron template without cover, it can be pressed through paper sheet or something like this.

If PCB is two-sided, drill four holes at edges (by marks), and after flipping adhese second side, observing side orientation. Glass table with light source under it helps in this a lot.

After the film is mounted, the PCB is put in the etchant.

 

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