ATMP = the process
The set of back-end steps (assembly, test, marking, packaging) performed on a wafer. It describes what is done.
Semiconductor · explainer
OSAT & ATMP, explained ATMP is the process. OSAT is the business model.
Assembly, Test, Marking & Packaging — the hands-on back-end work that turns a finished wafer into a usable chip.
The back-end flow
Die attach
Wire bond
Mold
Test
// process vs provider
Outsourced Semiconductor Assembly & Test — a specialist firm that performs ATMP for chipmakers, on contract.
Who does the work
Fab
OSAT
Packaged chip
a third-party provider, on contract
osat
What is OSAT?
OSAT stands for Outsourced Semiconductor Assembly and Test. An OSAT is a company that takes finished silicon wafers from a fab and turns them into packaged, tested chips ready to be soldered onto a board — on contract, for chipmakers who don't do that step themselves. Think of it as the specialist back end of the supply chain: fabs make the wafers, OSATs assemble, package and test them.
atmp
What is ATMP?
ATMP stands for Assembly, Test, Marking and Packaging — the back-end process that converts a completed wafer into a usable chip. It covers cutting the wafer into individual dies, mounting and wiring each die, encapsulating it, marking it, and testing that it works. In India's policy language (the India Semiconductor Mission), “ATMP” is the term used for this stage, and it's where most of the approved factory build-out is concentrated.
the difference
OSAT vs ATMP — what's the difference?
They're closely related and often used interchangeably, but they answer different questions.
OSAT = the business model
A third-party provider that performs ATMP for other companies. It describes who does it — an outsourced specialist rather than the chip designer in-house.
In short: every OSAT does ATMP, but not all ATMP happens at an OSAT (some chipmakers run their own in-house assembly & test). For skilling and hiring, the hands-on capability is the same.
the flow
The back-end flow, step by step
From a finished wafer to a tested, packaged chip.
Wafer dicing→
Die attach→
Wire bonding→
Molding→
Laser marking→
Trim & form→
Test & inspection
Wafer dicing
The wafer is cut into hundreds of individual dies (the bare chips).
Die attach
Each die is precisely mounted onto a leadframe or substrate.
Wire bonding
Ultra-fine wires connect the die's pads to the package's leads.
Molding
The die and wires are encapsulated in protective compound.
Marking, trim & form
The package is laser-marked, then leads are trimmed and bent to shape.
Test & inspection
Electrical test and quality inspection confirm each chip works before shipping.
packages
Package families you'll hear about
The “package” is the body that protects the die and connects it to the outside world.
QFN
Quad Flat No-lead — a compact, leadless package, very common in modern electronics.
SOIC & leaded
Small-Outline ICs and other leaded packages — the classic gull-wing chips.
BGA
Ball Grid Array — connections via a grid of solder balls under the package, for high pin counts.
Flip-chip
The die is flipped and bonded directly, removing wire bonds for speed and density.
Wafer-level (WLP)
Packaging done while still on the wafer, for the smallest possible footprint.
Advanced (2.5D / 3D)
Stacking and integrating multiple dies — the fast-growing frontier of packaging.
Why OSAT / ATMP matters for India now
India's approved semiconductor projects are weighted heavily toward assembly, test & packaging — the first units (Micron at Sanand; the CG Power–Renesas–Stars OSAT line) are an ATMP/OSAT build-out, and they recruit locally. Chip design talent is comparatively well-served in India; the binding constraint is hands-on manufacturing-floor skill. That's the gap — and the opportunity.
questions
OSAT & ATMP — quick questions
What is the full form of OSAT?
Outsourced Semiconductor Assembly and Test.
What is the full form of ATMP?
Assembly, Test, Marking and Packaging.
Is OSAT the same as packaging?
Packaging is one part of it. OSAT covers assembly and test as well as packaging — the whole back end, done on contract.
Is ATMP the same as the back end?
Yes — ATMP is the common name in India for the back-end stage that turns a finished wafer into a packaged, tested chip.
Building OSAT/ATMP skilling capability?
We advise institutions on real, plant-linked assembly, test & packaging programmes.