400A, 1000 V DC and 64 Fork Contacts: Benchmarking TE Connectivity (TE) HC-STAK 35 Against Rival EV High-Voltage Interconnects

For plant and program readers, the headline is simpler than the press release: the HC-STAK 35 from TE Connectivity (TE) is the high-current rung of a scalable high-voltage interconnection family, carrying up to 400A on 95 mm² conductors at 85 °C inside a rating envelope of up to 1000 V DC. Specify it for heavy, dual-motor or towing-capable electrified platforms; pass on it where the bus runs above that ceiling, as in 1500 V DC storage banks.

Mouser Electronics, Inc. has added the HC-STAK 35 high-voltage interconnection system to its stock, and the launch is worth reading as a market signal rather than a component bulletin. TE built the platform to route power between batteries, inverters and e-motors in electric, hybrid, plug-in hybrid and fuel-cell vehicles, and to do it while holding EMI shielding, touch-safe protection and resistance to vibration, mechanical load and heat. The demand curve behind it is measurable: Research and Markets projects the 800 V EV architecture market expanding from USD 13.8 billion in 2026 to USD 36.3 billion by 2031, a 21.3% CAGR, and higher-voltage, higher-current links are the components that carry that transition from PowerPoint to production. The relevant engineering question for industrial buyers is comparative: how much current headroom does this system actually buy a program, and against which alternatives?

Where does HC-STAK 35 sit inside the HC-STAK family?

Conclusion first: HC-STAK 35 is the tier you choose when continuous current, not voltage, is the binding constraint. Every connector in the HC-STAK family shares the same voltage ceiling — the series is rated up to 1000 V DC — so differentiation happens on the current and contact-stack axis.

HC-STAK family ladder: what changes between variants

Variant	Current capability	Conductor / thermal basis	Layered fork contacts	Design fit
HC-STAK 25	247A at +85°C (50 mm²), 296A at +85°C (70 mm²) per Mouser's published family spec list	Cable-limited	Lower stack count	Single-motor and mid-power battery-to-PDU links
HC-STAK 25 XE	Compact derivative	Space-constrained layouts	Up to 40 independent contact points (TE product flyer)	Dense engine-bay and inverter-adjacent routing
HC-STAK 35	up to 400A	95 mm² wires at 85 °C	up to 64 layered contact points	High-torque EVs, AWD and integrated-towing platforms

The scalability matters commercially. A fork-terminal architecture that can be layered from lower contact counts to up to 64 lets one supplier interface cover several powertrain grades, which cuts the number of distinct HV circuits a platform family must validate. TE's own HC-STAK 35 flyer frames the same benefit as unlocked vehicle performance without a new connector architecture per derivative.

How does it compare with rival high-voltage interconnect systems?

Read laterally, the 400A figure is a leading number but not an isolated one. Connector Supplier's industry roundup of high-voltage automotive connectors lists the Rosenberger HPK system at 275A at 85 °C and up to 1000 V, while Amphenol Industrial's ePower documentation claims that a single 400A connector can replace three conventional connectors, saving board and harness space. The differences that decide a design therefore sit less in headline amperes than in interface philosophy.

• Contact strategy. HC-STAK 35 distributes current across a stack of fork terminals (up to 64 contact points), whereas competing families often rely on a single machined-and-spring contact pair or a busbar joint. Stacking lowers interface resistance and heat, but it shifts the burden to assembly control.
• Termination route. TE pairs the low-resistance fork interface with optional ultrasonic welding; many rivals are crimp-first. Welding reduces steady-state loss, yet it demands weld-parameter qualification and dedicated cells — a factory-readiness question as much as an electrical one.
• Shielding and enclosure. EMI shielding is integral to the HC-STAK interconnects, which meet IP2XB touch-safe protection, IP67 ingress sealing and V0 flammability. Comparable sealed HV systems exist, so shielding alone will not differentiate a bid.
• Maintenance. Layered stacks are robust but not infinitely field-serviceable; programs that expect frequent open/disconnect cycles in service should compare mating-cycle ratings before standardising.

Which platforms should specify it — and which should walk away?

Buy-side verdict: HC-STAK 35 makes sense where power demand is structural rather than marginal. TE targets the system at high-performance EV and hybrid platforms that need higher torque, stronger acceleration and continuous power delivery, and the design benefits list calls out vehicles with higher curb weight, AWD systems or integrated towing capability — the heavy sub-classes where 250–300A links start to run hot.

Do specify it when:

• The DC link will legitimately carry sustained current in the 300–400A band, and 95 mm² cable is already the harness decision.
• The battery-to-inverter or inverter-to-e-motor path requires shielded, touch-safe, sealed routing that survives vibration and thermal cycling.
• Programme teams want one interface family spanning several powertrain outputs, using the layered fork stack as the scaling mechanism.

Do not specify it when:

• The circuit exceeds the vehicle-class ceiling. Stationary storage is migrating to higher bus voltages, with 1500 V DC systems described as an emerging mainstream in trade coverage of energy-storage connectivity; a component rated up to 1000 V DC does not qualify there.
• Current stays in the 100–250A range, where a smaller HC-STAK variant or conventional HV connector meets the duty cycle at lower cost and mass.
• The requirement is an auxiliary HV accessory circuit, where the 400A stack buys nothing but weight and tooling complexity.

Why IP2XB, IP67 and V0 are compliance items, not marketing claims

Touch-safe protection is increasingly written into regulation, which changes how a specifier should read these ratings. NHTSA's Federal Motor Vehicle Safety Standards rule text on electric-powered vehicles requires protection degree IPXXB for high-voltage live parts outside the passenger or luggage compartment, and requires all connectors to provide direct contact protection — either by meeting the probe requirement when unmated, by being tool-only separable, or by dropping live-part voltage to 60 V DC or below after separation. The ISO 6469-3:2021 standard likewise specifies electrical safety requirements for voltage class B circuits in electrically propelled road vehicles.

In that light, HC-STAK 35's IP2XB claim is the design-side counterpart of the IPXXB probe test, IP67 addresses dust and immersion exposure in the underbody environment, and V0 flammability performance covers the thermal-fault pathway regulators and insurers care about. Programs that treat these as optional line items in a specification sheet tend to discover them late, at homologation.

What trade-offs should engineering and purchasing price in?

1. Thermal derating is the real limit. The 400A capability is stated with 95 mm² wires at 85 °C; harness bundling, ambient soak and duty cycle all move that operating point. Validate with infrared measurement on the assembled loom rather than at the connector alone.
2. Conductor mass and cost. 95 mm² copper is heavy, stiff and expensive to route; aluminium alternatives and thinner-wire 800 V strategies exist precisely to avoid it, and thinner cable also lightens the power distribution unit.
3. Process capability. Optional ultrasonic welding lowers interface resistance and heat generation, but it adds equipment, parameter control and inline inspection to the build.
4. Scalability is not free. Each fork-stack configuration is a distinct electrical and mechanical object, so the up to 64 flexibility has to be paid for in validation scope.
5. Traceability exposure. HV interconnects are safety parts; a non-franchised supply route puts chain-of-custody at risk, which is why authorised-channel sourcing guidance still recommends manufacturer or named-distributor purchase as the default path even at a price or lead-time premium.

How supply and documentation reduce programme risk?

On the channel side, Mouser supports the launch as a global authorised distributor, with parts described as 100% certified, genuine and fully traceable back to manufacturer partners, and with stock held ready to ship. For design teams, Mouser's website carries a technical library that includes the Technical Resource Center, data sheets, supplier-specific reference designs, application notes, design information and engineering tools — the practical value being that early-stage ampacity and sealing questions can be answered from primary documents rather than broker listings.

What are the most common misconceptions?

• "1000 V DC means I can run an 800 V pack with unlimited margin." Voltage class headroom does not substitute for current, thermal or mating-cycle verification; the 800 V transition is a systems problem, and analysts tracking it point to thinner, lighter cabling and thermal management as the real constraints.
• "400A is a continuous, anywhere rating." It is tied to the stated 95 mm² / 85 °C basis.
• "IP67 covers touch safety." Ingress and touch protection are separate tests — IP2XB is the probe-protection claim, IP67 is the sealing claim.
• "Any family variant will do." Contact-stack count and cable size determine whether the interconnect is under- or over-specified.
• "Sourcing equivalence is fine for prototypes." Traceability gaps in HV safety parts carry warranty and recall exposure that prototype schedules hide.

What should an evaluation team do next?

• Chart every HV circuit's measured sustained current, then set the threshold: circuits trending toward the 300–400A band are HC-STAK 35 candidates; the rest stay on lower variants.
• Re-check the bus voltage of adjacent architectures — if a storage or heavy-industry derivative runs above 1000 V DC, open a separate component track instead of stretching this family.
• Run a weld-versus-crimp comparison for the specific loom, including cell cost, cycle time and inline inspection.
• Ask the distributor for lot-level traceability documentation and confirm part-number currency before releasing a build.
• Book thermal imaging of a mated, shielded assembly under representative duty before signing off the specification.

FAQ: quick answers for decision-makers

Is HC-STAK 35 only for passenger EVs?

The stated application set is electric, hybrid, plug-in hybrid and fuel-cell vehicles, where it links battery, inverter and e-motor. TE's wider HC-STAK material also addresses industrial and commercial electrification, but the 1000 V DC ceiling keeps it out of higher-voltage stationary storage buses.

What does "up to 64" actually buy a designer?

It is the layered fork-contact ceiling of the scalable architecture: more parallel contact paths give lower interface resistance, steadier electrical performance and a single interface that can be configured across several power levels instead of redesigned per grade.

How is 400A verified in a real vehicle?

The rating is published with 95 mm² wires at 85 °C, so verification means proving the assembled circuit — cable, termination, shield, enclosure and cooling path — holds that temperature rise under duty cycle, not testing the connector in isolation.

Where can I get design data before committing?

Primary data sheets and family specifications are published by TE and mirrored in distributor launch material; Mouser's Technical Resource Center aggregates data sheets, reference designs and application notes, which is faster than chasing supplier portals during a concept phase.

Sources referenced

• TE Connectivity — HC-STAK Series High-Voltage Interconnection System product page: https://www.te.com/en/products/connectors/automotive-connectors/intersection/hc-stak-series-high-voltage-interconnection-system.html
• TE Connectivity — HC-STAK 35 flyer (fork-terminal architecture, contact-point count): https://www.te.com/content/dam/te-com/documents/automotive/global/hc-stak35-flyer-v3-022526.pdf
• TE Connectivity — HC-STAK 25 XE flyer: https://www.te.com/content/dam/te-com/documents/automotive/global/hc-stak25-xe-flyer-v3-022526.pdf
• Mouser — HC-STAK family high-voltage interconnection systems, specification list: https://www.mouser.co.cr/en/new/te-connectivity/te-hc-stak-hv-interconnection-systems/
• U.S. Federal Register — Federal Motor Vehicle Safety Standards; FMVSS No. 305a, Electric-Powered Vehicles (IPXXB and connector contact-protection requirements): https://www.federalregister.gov/documents/2024-04-15/2024-07646/federal-motor-vehicle-safety-standards-fmvss-no-305a-electric-powered-vehicles-electric-powertrain
• ANSI — ISO 6469-3:2021, Safety for Electric Road Vehicles: https://blog.ansi.org/ansi/iso-6469-3-2021-safety-for-electric-road-vehicles/
• Connector Supplier — High-Voltage Automotive Connectors Product Roundup (Rosenberger HPK ratings): https://connectorsupplier.com/high-voltage-automotive-connectors-product-roundup/
• Research and Markets — 800V EV Architecture Market, 2026 to 2031 growth outlook: https://www.researchandmarkets.com/reports/6232114/800v-ev-architecture-market-strategic-insights
• PCBCart — Component traceability and counterfeit-avoidance guidance for franchised versus open-market channels: https://www.pcbcart.com/article/content/component-supply-chain-hmlv-pcba.html