Murali Srinivasa on how PCBs are made and why India lags

ELI5/TLDR

A printed circuit board is the green slab inside every electronic device — the thing the chips sit on, threaded with copper wires that connect everything. Cheap ones (a TV remote) are a single sheet of copper. Hard ones (a phone) are up to 60 wafer-thin copper sheets stacked and glued into something the thickness of a credit card, with wires running between layers through holes drilled by lasers. India was a leader in the easy kind in the 1980s, then watched China lap the field after 2000 — not because China had more money, but because American companies physically flew over and taught Chinese factories how to do it. India today has about 200 PCB factories; one Chinese province has 2,000.

The Full Story

The guest is Murali Srinivasa, who runs Lion Circuits, an Indian PCB maker, and previously worked at the chip company Texas Instruments. The interviewer (Markets by Zerodha) keeps stopping him to define acronyms, which makes this an unusually clean explainer.

What a circuit board actually is, with bulbs

Start with the parts vocabulary. A chip — or IC, integrated circuit — is the small black square that does the thinking: the logic, the programming, the decisions. But a chip is useless on its own. It has dozens or hundreds of tiny metal pins that need to connect to other components and to power. The PCB is the thing all of that gets mounted onto and wired together. Chips are the brains; the PCB is the nervous system and skeleton.

Srinivasa’s analogy: imagine a building with a main electrical panel and a row of bulbs, with wires running from the panel to each bulb. Now shrink that whole thing a thousand times. The wires become copper tracks — thin lines of copper printed onto a board. The panel becomes the connector where input comes in. The bulb might be an LED. And the logic that decides when the bulb turns on — say, when a room gets too hot — lives in a chip sitting on the board.

So in very simple thing like if you have seen any TV circuit boards like those green color big boards, those are all basically circuit boards.

Why a board needs 60 floors

Here is the part worth slowing down on. A board is described by how many layers it has, and a layer is best thought of as a floor in a building.

A TV remote is a bungalow — single layer, one floor. One sheet of non-conductive material (a dielectric, meaning it doesn’t carry electricity) with a single layer of copper on top. Simple job, simple board. India solved this in the early 1980s.

A phone is a skyscraper. Inside a slab about 1 to 1.5 mm thick — roughly two credit cards — there can be 40, 50, even 60 layers of copper, each one a floor, all compressed and bonded into a single piece. Why so many? Because electronics keep shrinking while doing more. The phone gets thinner, the camera gets bigger, the screen eats the surface area — so the space left for the board keeps shrinking even as the number of things that need wiring keeps growing. Same problem as a city: more people, less land, so you build up. A smartwatch, despite looking trivial, is nearly as dense as a phone.

Your floor area is reducing, your effective area is reducing, but the density is increasing. So you need to squeeze in more.

How you build the floors: light, then acid

Making one layer is a printing-and-removing trick. You start with a plain sheet of copper. You want to keep copper only where a wire needs to run and strip it everywhere else.

First, an engineer draws the wiring in CAD software — every wire’s path, width, and shape. That drawing becomes a circuit pattern. To stamp that pattern onto the copper, you coat the copper in a photosensitive material (a chemical that hardens or softens when light hits it — same family of trick as old film photography) and shine the pattern image onto it. This is photolithography — literally “drawing with light.”

Then comes etching: a chemical bath, often ammonia, that eats away the exposed copper but leaves the protected copper behind. What survives is your circuit. Picture spray-painting a stencil onto a sheet, then dunking it in acid that dissolves everything the paint didn’t cover.

Now do that for all 50 floors and glue them into one stack.

The two hard problems: staircases and alignment

Floors are useless if you can’t move between them. The connection from one layer to another is a plated-through hole — a hole drilled through the board and lined with conductive metal so electricity can travel up and down. The interviewer’s word for it: a staircase. The first time a factory learns to do this reliably is the first real jump in difficulty.

The second hard problem is registration — keeping all the stacked layers lined up. You can’t see the inner floors once they’re buried, so if the fourth-and-fifth-layer sheet shifts even 50 microns (a human hair is about 100 microns, so half a hair), the staircases no longer meet their landings and the entire board is scrap. Raw material in the bin.

If it moves by that much, your entire board is gone. You just have to dump it.

HDI: the penthouse with its own private elevator

The most complex tier is HDI — high density interconnect. It’s a multi-layer board with one extra trick: blind and buried vias (a via is just the technical word for an inter-layer connection). A normal staircase runs the full height. A buried via connects only two inner floors and is sealed inside, invisible from outside — like a private staircase between floors 2 and 3 of a building. A blind via opens onto the surface but stops partway down.

The point is real estate. With a buried via sealed inside, you can run another wire directly on top of it without interference — you’ve recovered the floor space above the staircase. When holes are as small as 25 microns, you can’t drill them mechanically; you need laser drills, machines most factories simply don’t own. HDI is what’s inside every phone and smartwatch. Multi-layer (a step below) is what runs a car’s engine control unit — modern cars are “drive by wire,” electronics talking to electronics.

Why India fell behind: it was never about money

India was genuinely ahead in the 1980s. A company called United Telecom set up the country’s first fully automatic single-layer line in Bangalore in the mid-80s, and through the 90s India made landline phones almost entirely domestically — plastics, PCBs, the lot. Then China pulled away after 2000, and Srinivasa is blunt that the cause wasn’t capital.

His framing is know-how — and his test case is a jet engine. Hand him 10,000 crore rupees and six months and ask for a Boeing engine: impossible. The design might be doable; the making is the wall. Manufacturing is a process industry, where the same machine and the same chemical at a different temperature produce a different result, and nobody has written down which settings work. That’s tacit knowledge — or as he calls it, tribal knowledge: you only get it by being in the tribe.

Only people who have done it, only people who know how to do it, know how to do it.

China got handed the tribe. When American firms offshored manufacturing in the early 2000s, they sent engineers to set up the factories, specify the materials, and show every step — Apple still flies people in to teach, he notes. China learned and compounded. India, meanwhile, undercut its own industry: customs reforms in 2002–04 let factories import machines duty-free, but finished boards from China could also enter duty-free and cheaper, so why bother making them. The flagship Bangalore plant shut in 2020.

The copper and chemical problem

Two supply-chain weak points compound the know-how gap. India used to be a net exporter of copper — the Sterlite plant in Tamil Nadu alone covered 30–40% of national copper needs. After it closed, India became a net importer, and copper is the single biggest cost in a board (the raw material, copper-clad laminate or CCL, is roughly 30%+ of cost). As the interview was recorded in October, CCL prices had jumped 10–20% in a month, driven mostly by the rupee-dollar rate. Second, the specialty chemicals for the wet processing — etching, electroplating — are largely imported from Germany, Europe and the US; India has the chemistry colleges but not the proven recipes. Government schemes (ECMS, plus Adani’s Gujarat copper plant and a 500-crore CCL commitment) aim to fix both, but, he repeats, it takes time and know-how.

Key Takeaways

A PCB (printed circuit board) is the substrate that chips/ICs mount onto; chips do the logic, the PCB carries the connections via copper tracks.
Boards are classified by layers: single-layer (TV remote), double-layer, multi-layer (MLB, car engine control units), and HDI (phones, smartwatches). A phone PCB packs ~40–60 copper layers into a ~1–1.5 mm slab.
More layers exist because shrinking devices leave less board area but demand more connections — vertical density, like a skyscraper.
A single layer is made by photolithography (light prints the wire pattern onto photosensitive-coated copper) then etching (a chemical bath, often ammonia, dissolves unwanted copper).
Inter-layer connections are plated-through holes (“staircases”); HDI adds blind and buried vias to reclaim board space, requiring 25-micron holes made by laser drills.
Registration (layer alignment) is a key difficulty: a 50-micron shift (half a human hair) scraps the whole board.
A PCB needs ~20–25 machines to produce; by contrast EMS (assembly) needs only ~3 (printer, pick-and-place, reflow) — which is why India has 2,000–3,000 EMS factories but only ~200 PCB factories.
Of India’s ~200 PCB factories: ~150–160 do only single-layer, ~20–30 double-layer, ~10–15 multi-layer, and only 1–2 do HDI (prototype scale only — no HDI plant at scale in India).
Shenzhen/Guangdong province alone has ~2,000 PCB factories; India’s largest plant wouldn’t crack China’s top 50.
India led single-layer in the 1980s–90s (United Telecom made domestic landlines, PCBs included); that flagship Bangalore plant closed in 2020.
China’s leap after 2000 came from US firms physically transferring manufacturing know-how, not from capital — “tacit/tribal knowledge” that isn’t documented.
Customs reforms (2002–04) removed import duty on machines but left finished Chinese boards entering duty-free and cheaper, undermining domestic manufacturing.
Copper is the biggest board cost; copper-clad laminate (CCL) is ~30%+ of cost. India became a net copper importer after the Sterlite (Tamil Nadu) plant — ~30–40% of national supply — closed.
Specialty PCB chemicals are mostly imported (Germany/Europe/US); no strong domestic high-quality electroplating-chemical maker exists.
Lion Circuits can manufacture 75-micron track widths; most Indian factories manage only 150–200 microns; 25 microns remains out of reach.

Claude’s Take

This is one of the better “how is this thing actually made” interviews I’ve processed, largely because the interviewer refuses to let jargon slide — every acronym gets a “sorry, what’s that?” The building/floors/staircases analogy is carried consistently enough that the manufacturing mechanics genuinely land, which is rare.

The honest part is the know-how argument, and it holds up. The claim that China’s lead came from transferred tacit knowledge rather than cheap capital is the real insight, and it’s the kind of thing that’s easy to assert and hard to falsify — but the jet-engine framing makes it intuitive, and the 75-vs-150-micron detail from his own factory grounds it in something concrete rather than hand-waving.

The soft spots: Srinivasa runs a PCB company and is openly lobbying viewers to build PCB factories, so the “India is heading in the right direction” framing has a thumb on the scale. The numbers are all “from what I can recollect” and “around” — the 200 factories, the 2,000 in Shenzhen, the copper percentages — directionally believable, not audited. And there’s a recurring “that’s a different story” whenever something gets politically or commercially awkward (why the Bangalore plant closed; how exactly China acquired its know-how), which leaves the most interesting questions parked.

Score 8: as a clear, well-structured primer on PCB manufacturing and why manufacturing capability is stickier than money suggests, it’s genuinely educational and quotable. Docked from higher because the India-vs-China analysis is solid intuition rather than rigorous data, and the speaker has skin in the optimistic version.