A product survives a drop test because someone designed the load path for the impact, not because the plastic happened to be tough. That means deciding in advance how far it falls, onto what, and how many times; then giving the impact energy somewhere to go besides the screen, the battery, or the solder joints. The first drop will happen — in the factory, in shipping, in a customer's kitchen — so the real design question is not whether it gets dropped but what breaks when it does.

Define the test before you design for it

"It should survive being dropped" is not a requirement. A testable one specifies four things:

  • Height. Handheld consumer products are commonly tested from about waist to shoulder height; something used on a workbench needs less; something worn on the body may need more, because it falls from standing height onto whatever is underfoot.
  • Surface. A drop onto steel or concrete is drastically harsher than onto vinyl tile or wood. The surface is often the difference between passing and failing, so it must be stated.
  • Orientations and repetitions. Serious protocols require drops on every face, every edge, and every corner, repeated on multiple samples. One lucky drop proves nothing.
  • Pass criteria. No hazardous exposure? No functional loss? No cosmetic damage? These are three very different products at three very different costs.

Write all four into your requirements document, because the design and the test lab both need the same definition. If your product falls into a regulated category, the applicable standard usually dictates the protocol — see product safety testing requirements for how that works in the US.

The physics: corners are the enemy

Drop severity is governed by how quickly the product is brought to a stop. Kinetic energy at impact depends on mass and height, but the peak force depends on stopping distance and time. Anything that spreads the impact over more distance and more milliseconds reduces the force reaching internal parts.

A flat-face drop distributes load over a large area and is usually survivable. A corner drop concentrates the entire energy into a point, so stress rises sharply and the shell can transmit a violent shock spike straight into the components behind it. Corner and edge drops are what actually break products.

Design responses that work:

  • Radius and soften the corners. Generous fillets both spread contact area and remove stress concentrations.
  • Add sacrificial crush structure. Ribs, bumpers, or a compliant overmolded corner that deforms absorbs energy the rigid shell would otherwise transmit — one of the strongest arguments for overmolding a soft outer layer.
  • Avoid sharp internal corners. Every unfilleted internal corner is a crack initiation site, which is also why uniform wall thickness with proper fillets improves drop performance as a side effect.
  • Choose a tough material, not just a strong one. Toughness — energy absorbed before fracture — is what matters in impact. Polycarbonate and PC/ABS blends outperform stiffer, more brittle materials here; the comparison in ABS versus polycarbonate is directly relevant.
  • Watch cold temperatures. Many plastics become markedly more brittle below freezing, and a product that passes at room temperature can shatter after a night in a car.

The inside matters as much as the shell

Most drop failures are not cracked housings. They are internal:

  • Heavy components tearing loose. Batteries, motors, speakers, and transformers have mass, and mass times deceleration is a large force applied to whatever holds them. Support heavy parts on multiple sides and near their center of mass, never on a single glued tab.
  • PCB flex. A board that bows during impact cracks solder joints on large components, snaps ceramic capacitors, and unseats connectors. Support boards close to heavy parts and avoid long unsupported spans.
  • Display and glass. Screens fail in bending. They need a compliant gasket, a bezel that keeps the glass off hard plastic, and a stiff structure behind them so the glass is never asked to carry load.
  • Fastener pull-out. Self-tapping screws in thin plastic bosses strip under shock. Deeper bosses, gussets, or heat-set inserts fix this.
  • Connectors and cables. Provide strain relief and enough service loop that a shifted assembly does not pull a connector off its footprint.

Predict before you drop

Explicit dynamic FEA simulation can model the milliseconds of impact and show you where stress concentrates, how much the board flexes, and how a design change alters the outcome — before any part exists. It is not a substitute for testing, because material behavior at high strain rate and real assembly variation are hard to model, but it is excellent at ranking design options and at explaining why something failed.

Then test physically, and test early. Drop a rough prototype before the enclosure is finalized, even if it is 3D printed and you have to mentally discount the material difference — printed parts are more brittle and layer-dependent, so a printed housing that survives is genuinely encouraging while one that cracks may still be fine in molded form. Repeat with production-material parts at the DVT stage, on multiple samples, with the actual protocol.

Drops are not the only shock your product will see

Vibration is a separate failure mode with separate physics: low forces applied millions of times, which loosens fasteners, wears contacts, and fatigues wires. Packaging and transport testing exists because a pallet on a truck experiences hours of vibration that no single drop replicates, and packaging design is part of the answer — a product that cannot survive a bare drop can still ship safely if the box is engineered to absorb it. Decide deliberately how much protection lives in the product and how much lives in the package.

Working on an enclosure that has to survive real-world handling? Reach out through our contact form and we will help you define a realistic drop protocol and design the structure to pass it.