Heat Staking PCBs: Secure the Board Without Screws
By Alex Spurgeon — 2026-06-01
Heat staking a PCB means melting a plastic boss in the housing down over the edge of the board so it forms a little rivet head and holds the board in place. No screws. No standoffs. No bag of M3 fasteners that the line keeps running out of at 4pm on a Friday.
It is the quiet workhorse of electronics assembly. Most people carrying a device in their pocket right now have three or four staked bosses holding a board down, and they will never know it. Which is sort of the point. A good stake is like a good referee: if you noticed it, something went wrong.
What heat staking a PCB actually does
You start with a plastic housing that has bosses moulded into it — little posts standing up where the board needs to sit. The board drops over those posts so the bosses poke up through the mounting holes. Then a heated tip comes down, softens the top of each boss, and forms it into a head that overlaps the hole. The plastic cools, the head goes solid, and now the board is pinned down by a part of the housing itself.
The impulse method we build runs it as three steps: Heat, Cool, Retract. The tip heats the boss just enough to flow, holds form while compressed air cools the plastic, then lifts away clean. No sticking, no stringing, no little plastic whiskers bridging your traces. (Stringing on a bare board is exactly the mess it sounds like — it made a mess and left without cleaning up.)
The temperature is set by the plastic, not by us. ABS and polycarbonate soften over a wide, forgiving range. Nylon and PP have a sharp melt point — a few degrees cold and nothing flows, a few degrees hot and it scorches. If you want the long version of the cycle, the step-by-step process guide walks through it.
Staking vs screws and standoffs
The default way to hold a board in a box is screws into standoffs. It works. It is also the most expensive thing on the bench once you count it honestly: the screw, the standoff, the driving step, torque control, and the back-out risk when the unit lives somewhere that vibrates.
Heat staking trades all of that for a moulding feature you often need anyway. Once the tooling is set, the per-cycle cost is close to nothing — no fastener, no driver, no torque check. At real volume it wins on cost and on cycle time, and a benchtop press can form up to 8 bosses in a single stroke, so a four-corner board plus a couple of mid-board holds is one cycle, not six screws.
Here is the honest part, because somebody has to say it. If the joint needs to come apart in the field, a stake is the wrong call. A solid staked head is a one-shot plastic rivet — strong in clamp and shear, weak in straight pull-out, and destroyed the moment a tech tries to open it. If your product gets serviced, calibrated, or has a battery a customer swaps, don't stake those points. Use a screw, or use a brass insert (more on that below). We would rather tell you that now than after you have tooled it.
Don't cook the board: protecting the PCB
This is where staking a PCB differs from staking two bits of plastic together. There is an actual circuit in the clamp zone, and it does not enjoy being squashed or warmed.
Three things to get right:
• **Standoff height.** The boss has to sit the board at the right height for the tallest component underneath, with clearance to spare. Crush the board down onto a tall cap and you have a short, not a product. Standard standoff heights run anywhere from about 3 mm to 25 mm depending on what is on the bottom of the board.
• **Clamp force.** The head only needs to overlap the hole and hold the board flat. More force does not mean more strength — it means a flexed board and stressed solder joints that pass inspection and fail three months later out in the field. Stake the board *down*, don't crush it.
• **Keep the head clear.** The molten plastic flows outward as it forms. Lay out a keep-out ring around each mounting hole so the head never reaches a trace, a pad, or a component body. The hole position is a board-design decision, not something you fix at the press.
Our presses use a 0.1 mm linear encoder to confirm every boss is present and stops the head at the right depth each cycle, which is the difference between a repeatable hold and a board that gets mashed on whichever cycle the operator leaned on it. For the standards side of board layout and acceptability, the IPC association is the reference everyone in electronics assembly actually uses.
Solid or hollow — and can you ever get back in?
Default to a solid head when the board stays put for life. It is the simplest, strongest hold.
Reach for a hollow head when the show face matters or you want a big head with less melted material — a hollow stake gives a wide, strong head with no sink mark telegraphing through to the outside of the housing. We had a medical-enclosure job exactly like this: clean permanent hold on most of the board, but the techs still needed to open units for service. Hollow bosses on the serviceable corners gave them a head they could drill out once and re-close with a self-tapping screw, instead of destroying the boss every visit.
And if a point genuinely needs to come apart again and again — service access, a calibration cover — that is a brass insert, not a stake. Heat the tip, soften the plastic around a moulded hole, press a knurled insert in, let it solidify around the knurls. Now it takes a machine screw, comes apart as many times as you like, and holds more torque than a screw biting raw plastic ever would. The honest guide to heat staking inserts covers that trade in full.
Boss design and material, briefly
The head needs somewhere to come from. Rule of thumb: the plastic standing proud of the board should roughly equal the volume of the head you want, and a standard dome wants the boss sticking up about 1.5–2× its diameter. Too little material gives a thin, weak cap. Too much folds over and traps voids.
On material: amorphous plastics like ABS, PC and PC/ABS forgive you because they soften gradually across a wide glass-transition range. Semicrystalline ones — nylon, acetal, PP — have a sharp melt point and a narrow window, so they want tighter control. And glass-filled grades do not form clean heads — the fibres don't melt, so the head comes out matte and hairy and fails pull tests. If you are stuck with 30% glass-filled nylon, switch to a hollow or flared head, or rethink whether staking is the join at all. These all work with the impulse method, which handles ABS, polycarbonate, nylon and PP. If you want the equipment side of this, see the impulse heat staking system and the Benchtop Press.
When not to stake a PCB
A quick gut check before you commit the tooling:
• The board gets serviced, swapped, or opened in the field — use screws or inserts.
• The plastic is a thermoset (phenolic, epoxy) — it can't be reheated to flow, so it can't be staked, full stop.
• There is no room for a keep-out ring around the holes — fix the board layout first.
• The board carries constant pull-out load straight off the head — stakes are weak in that direction by design.
Everything else — the ordinary "hold this board flat in this box, forever, at volume" job — is exactly what staking is for. This is the bread and butter of electronics assembly, and it is the application we get asked about most.
FAQ
Does heat staking damage the PCB?
Not if it is set up right. The heat is local to the boss and brief, and the board never reaches a damaging temperature. The real risks are mechanical, not thermal: too much clamp force flexing the board, or a head flowing into a trace. Control depth and force and keep a keep-out ring around each hole.
Heat staking vs screws for a PCB — which is better?
For high volume where the board stays put, staking wins: no fasteners, no driving step, lower per-part cost, and good vibration resistance. For anything that needs service access or field disassembly, screws (or brass inserts) win, because a solid stake is permanent.
What temperature do you heat stake a PCB at?
It depends entirely on the plastic, not the board. ABS and polycarbonate flow over a wide range and are easy to hit; nylon and PP have a narrow window. Anyone quoting one fixed temperature for every material doesn't understand the job.
Should I use a solid or hollow stake on a PCB?
Solid for a permanent, maximum-strength hold. Hollow when you want a large head with less material, a cleaner outer surface with no sink mark, or the option for a tech to drill it out and re-close with a screw later.
How tall should the standoff or boss be?
Tall enough to clear the tallest component on the underside of the board with margin. Common standoff heights run from about 3 mm to 25 mm. Measure the bottom-side components first, then set the boss height — never the other way around.
Can a heat-staked PCB be removed for repair?
A solid stake is one-shot — you drill the head off and the boss is spent. If you need repeatable access, design those points as brass threaded inserts or screws from the start, and keep the staked points for the holds that never need to open.
Get the standoff height, the clamp force, and the keep-out right, and a staked board will outlast the product, the warranty, and possibly the firmware. If you have a housing and a board and you are not sure it will stake clean, send it over — we run a free evaluation and turn a quote around in 24 hours, no fastener bag required. Give us a call.