Applications · Pressure sensor assemblies

Pressure Sensor Assembly Welding

Pressure sensor assemblies join the sensing diaphragm to the housing and the housing to the process interface — the sealing welds that let the sensor hold its measurement in a pressurized medium. The diaphragm sits at tens of microns thick, so excess heat dishes it, and any dishing directly shifts range and linearity.

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[TODO: hero image — laser welding a thin stainless diaphragm onto a pressure sensor housing]

Typical joints

Typical pressure sensor parts and joints

Pressure sensor welding covers a recurring set of joint forms:

Sensing diaphragm to housing seal weld — thin foil onto a bulkier housing, most often 316L stainless
Housing to process interface fitting — threaded, flanged or clamp-style connections that need a leak-tight joint
Electrical feedthrough seal — glass-to-metal or ceramic-to-metal transitions carrying signal wires out of the sealed cavity
Dissimilar-metal joints where the diaphragm alloy differs from the housing (Hastelloy diaphragm on a 316L housing for chemical-service sensors, for example)
Batch-produced media-isolated sensors for hydraulic, pneumatic and refrigeration lines
Medical and food-grade sensors requiring specific alloy pairs and downstream helium leak-check verification — see medical device and automotive sensors for adjacent programs

Process fit

Which process fits pressure sensor assembly welding

Laser (dominant)

The process that carries this application

Low heat input and a tightly focused beam produce thin-diaphragm welds without dishing the foil. Autogenous seams add no filler to the sealed cavity. Hermetic sealing applications rely on laser-quality weld consistency. Fiber and pulsed benchtop platforms both fit depending on part size and volume. See the laser line →

Pulse arc / Micro TIG

Repair scenarios only

Arc heat is too much for production diaphragm work, but pulse arc has a role in repair — rebuilding a damaged process fitting, or tacking a component before the sealing pass. See the pulse arc line →

Resistance spot

Generally not a fit

Two-sided access, visible surface marks and difficulty holding leak-tight seams rule out resistance spot for diaphragm work. Occasional use survives for cold-weld electrical terminal attachments away from the sealing surface. See the resistance spot line →

Because the customer’s leak-check verification is the true acceptance criterion, sample welds run through the actual customer inspection flow are the only way to lock the process choice for a specific sensor design.

What’s hard

Common difficulties in pressure sensor assembly welding

Five failure modes recur across pressure sensor welding programs:

Diaphragm deformation from excess heat — a diaphragm even slightly dished by the weld reads a shifted range, so energy must stay below the deformation threshold — much tighter than for a structural seam.
Fixture registration accuracy — the seal weld path has to trace the same geometry every cycle; a fixture that drifts leaves gaps that leak under the customer’s helium check.
Porosity is a leak path — any gas entrapment during solidification becomes a pinhole in the sealed cavity; shielding-gas coverage, joint cleanliness and pulse-shape control combine to prevent it.
Batch consistency drives leak-check yield — parameter drift across a production run shows up as fluctuating rejection rate on downstream verification; parameter stability is not optional.
Dissimilar-metal pairs (Hastelloy-to-316L, titanium-to-stainless) require pulse shaping and sometimes asymmetric focus positioning to fuse both sides evenly.

Pressure sensor welding is unforgiving — diaphragm geometry, alloy pair and downstream leak-check flow all shape the parameter window. The most reliable way to lock the process is a sample weld on the actual sensor build, run through the actual acceptance test. The evaluation itself is free.

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