The Via Needed a Way to Breathe

The solderless interconnect targeted dense BGA geometry at 0.4 mm pitch. Laser-drilled adhesive masks placed CircuitScribe ink over each contact. Capillary action filled the holes, but trapped air interrupted the conductive path.

Stabbing each ink-filled hole with a fine copper wire released the bubble and helped the ink dry. That change produced preliminary readings below 1 ohm through a via and above 100 megaohms between neighboring vias.

Eight Steps Built the Test

1. Laminate pink Avery Neon 5975 sticker stock for the lower laser-drilled layer.
2. Cut the BGA hole pattern with a 3 W engraver at 0.050 mm per pixel.
3. Apply the laminated layer to the BGA contact surface.
4. Cut the same pattern into non-laminated Avery stock to create the conductive-ink mask.
5. Align the two hole fields and place the ink mask over the laminated layer.
6. Fill each opening with CircuitScribe ink while controlling bubbles and capillary flow.
7. Puncture every filled hole with a fine copper wire while supporting the chip on a firm surface.
8. Lift the upper mask before the shorted ink film on its surface dries into the assembly.

The Full Stack Revealed the Material Problem

The later assembly failed because the ink permeated Avery paper fibers, spread between the two adhesive layers, and never reached the pads. The experiment therefore separated two mechanisms: copper-wire puncture solved trapped air inside the opening, while porous paper redirected the conductive path away from the contact.

The next iteration can keep the laser alignment and bubble-release steps while changing mask porosity, ink flow, pad contact, and drying. That is how a maker-scale process advances: each electrical measurement turns invisible material behavior into a design variable.

The Missing Maker Fab is the larger invitation to develop processes like this into useful fabrication capability.