Resources · Reference

The Visitech technology glossary

DLP imaging, direct imaging lithography and additive manufacturing carry a vocabulary that is half acronym. This is what we mean by each of them — in plain terms, written by the engineers who build the hardware.

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A to Z

Every term, defined

Search for a term, or narrow the list to a theme. Every entry links to itself, so you can send a colleague straight to the definition you meant.

20 terms

A

Artwork
The pattern data to be exposed — the layout as it comes from CAD, in a format such as Gerber, ODB++, GDSII or OASIS.

C

Critical dimension
The feature size a process is measured against — the one dimension that has to hold, everywhere on the substrate and from panel to panel.

D

Direct imaging lithography
Lithography with no photomask: the pattern comes from a digital file and is written straight onto the substrate. Every panel can therefore be exposed differently, which is what makes per-panel correction possible.
1 page · 4 articles — what Direct imaging lithography links to

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E

Exposure
The act of projecting the pattern onto the substrate, and the dose of light delivered while doing it. Both the pattern and the dose have to be right for the layer to develop as designed.
1 product · 1 page · 6 articles · 1 document — what Exposure links to

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Exposure speed
How fast the head can deliver the required dose over an area — the throughput figure once the material's sensitivity is known.
1 product · 1 document — what Exposure speed links to

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F

Fine-line
Shorthand for work at line widths small enough that the substrate's own movement and the imaging system's accuracy become the limit — in PCB and packaging terms, roughly 15 µm and below.
3 products · 1 article · 3 documents — what Fine-line links to

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I

Inner layer
A conductor layer inside a multilayer board, laminated between others. Inner layers are imaged before lamination, so their registration to the layers added later is what decides whether the finished board works.
1 article — what Inner layer links to

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L

L/S
Line/space — the standard way of stating how fine a lithography process can go: the width of a conductor and the gap beside it, usually as one number when both are equal, e.g. "15 µm L/S".
Line/space
The width of a conductor and the gap next to it — the standard measure of how fine a lithography process can go. Usually written as one figure when both are equal, e.g. "15 µm line/space".
4 articles — what Line/space links to

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Line edge roughness
How ragged the edge of an exposed line is when looked at closely. It matters most where the line width is small enough that the roughness is a real fraction of it.
1 product · 1 document — what Line edge roughness links to

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Line width
The width of a single exposed feature. How closely it matches the design across the whole substrate is one of the two numbers, with registration, that a lithography process is judged on.
Lithography
Transferring a pattern onto a substrate with light. In electronics manufacturing it is how conductors, soldermask and other layers are defined before they are etched or developed.
1 product · 5 pages · 3 articles · 1 document — what Lithography links to

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M

Maskless
Without a photomask. A maskless process has no mask to make, store, align or replace when the design changes — the design change is a file change.
3 articles — what Maskless links to

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O

Outer layer
The conductor layer on the surface of a board, carrying the pads that components are soldered to.
4 products · 1 article · 4 documents — what Outer layer links to

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R

Registration
How accurately one layer lines up with the one under it. On a substrate that has stretched or warped since the previous layer, good registration means correcting the pattern rather than assuming the substrate is where it should be.
1 article — what Registration links to

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S

Semiconductor
A material whose conductivity can be controlled, and by extension the industry that builds chips from it.
6 articles — what Semiconductor links to

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Soldermask
The protective layer over a board's copper, opened only where components are to be soldered. On fine-pitch boards its openings have to be placed as accurately as the copper underneath.
3 products · 3 documents — what Soldermask links to

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Stepper
A lithography tool that exposes one field, moves the substrate, and exposes the next — as opposed to scrolling continuously past the substrate.
4 articles — what Stepper links to

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Substrate
Whatever is being exposed: a panel, a wafer, a board, a package carrier. The word is used when the process does not depend on which of those it is.
6 products · 1 article · 5 documents — what Substrate links to

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W

Warping
Deforming the pattern before exposure so that it fits a substrate that is not the shape it was designed for — scaling, rotating and locally distorting the artwork to match the panel actually in the machine.
1 article — what Warping links to

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Still not clear?

Ask the people who built it

A definition only goes so far. Tell us the substrate, the line/space you are aiming at and the format, and we will come back with what it means for your machine — usually within two business days.

Ask an engineer