The Test
The experiment was a solderless interconnect process for dense BGA-style contact geometry. The target pitch was 0.4 mm. The process used laser-drilled adhesive masks and CircuitScribe conductive ink.
The important measurement was electrical, not decorative: preliminary tests reached less than 1 ohm via resistance and more than 100 megaohm inter-via isolation.
Process Steps
- Laminate pink Avery Neon 5975 stickers for laser drilling.
- Laser-drill the BGA holes in the laminated Avery mask using a 3 W engraver at 0.050 mm per pixel.
- Stick the laminated Avery mask to the BGA.
- Laser-drill the same BGA-hole pattern in a second non-laminated Avery sheet to make the conductive-ink mask.
- Precisely align the holes and place the non-laminated mask on top of the laminated one.
- Apply CircuitScribe conductive ink to each hole while watching for trapped air and capillary effects.
- Puncture each ink-filled hole with a small copper wire to release trapped air and improve drying. Keep the chip on a firm surface so the ink is not pulled sideways between holes.
- Remove the non-laminated mask before the ink on top of that mask becomes part of the structure.
What The Step Fixed
The copper-wire puncture step was the useful change. It gave trapped air a path out of the ink-filled vias and reduced the chance that bubbles or incomplete fill would dominate the electrical result.
The tradeoff is process sensitivity: alignment, surface support, ink drying, and capillary behavior matter at this pitch.