Sub-system
Inside a rack, accelerators are joined by copper — cable harnesses and backplane connectors carrying tens of gigabits per lane over a metre or two. It is a precision manufacturing business, it is a real lead-time item on AI racks, and it is where a surprising amount of an interconnect's performance is won or lost.
In one sentence
High-speed cables and connectors are the passive and active copper assemblies, backplanes and mating connectors that carry serial links between boards, chassis and racks at multi-gigabit rates.
A high-speed connector is a controlled-impedance structure, not a set of contacts. Its geometry, shielding and materials determine reflections and crosstalk, and at current rates the connector can consume a large share of the total channel loss budget. Designing one is a radio-frequency problem, and qualifying it takes years.
Assemblies come in two forms. Passive copper needs no power and works over short reach. Active copper embeds a retimer at one or both ends, extending reach for a modest power cost — which is the middle rung between passive copper and optics, and increasingly where rack-scale systems land.
A rack-scale system joins dozens of accelerators with many lanes each, and the harness that does it can contain thousands of individual conductors terminated precisely at both ends. That assembly is built by hand or by specialised machinery, and its lead time has appeared on the critical path for AI rack deliveries.
How far copper can carry a lane decides how far apart two accelerators can be, which decides the physical layout of the rack, which decides how large a tightly coupled domain can be. It is a case of a material property setting a system architecture rather than the other way round.
Technology dependencies are solved by engineering; supply dependencies are solved by building something, which takes years.
An active copper assembly is a cable with retimers in its housings. Without them the same copper carries the signal roughly half as far, which changes what can be wired together in a rack.
SerDes and retimersBackplanes and connector carriers are built from copper foil bonded to laminate, and the loss of that laminate is part of the channel budget. Cheaper material means shorter reach.
Copper foil and laminateCages, pinouts and mechanical mating are specified in common so a cable from one supplier fits a port from another. Without that a rack could only be wired with one vendor's parts.
Thousands of conductors are terminated and tested per rack, largely by hand on trained lines. Adding capacity means hiring and training people, which is slower than adding a machine.
Other pages in this map that name Cables and connectors as something they cannot do without.
What each company supplies at this step, and — where a public figure exists — its share of this specific market — with what that share measures, the period it covers and who published it. Some rows also show the company’s own reported revenue for the segment covering this step, which is a different thing: it says how much this business matters to that company, not how much of the market it holds. Not a ranking and not a recommendation.
Supplies high-speed connectors, cable assemblies and backplane interconnect.
Communications Solutions segment — 52.0% of Amphenol’s reported revenue ($12.2B)FY2025 · company filings · not a market share
Supplies connectors and interconnect systems for data-centre equipment.
Manufactures high-speed cable assemblies and connectors at volume.
Supplies the retimer silicon inside active electrical cables.
One of the three connector houses whose backplane and cable systems the rack designs are built around.
Builds the cable assemblies and connector sets into the racks it also assembles.
Supplies high-density board and cable connectors where the pitch is tighter than the volume houses serve.
Assembles the high-speed copper cables that carry short-reach links inside and between racks.
The connector arm of the group that assembles the racks, supplying parts into its own integration lines.
Supplies high-density board and cable connectors at pitches the volume houses do not serve.
Assembles the high-speed copper cables carrying short-reach links inside and between racks.
Supplies the sockets and board connectors accelerators and processors are seated in.
Whether copper reach holds at the next per-lane rate or forces optics further into the rack.
Whether cable assembly capacity keeps pace with rack-scale system deployment.
Whether active copper takes share from short-reach optics.
Each page explains one technology in plain language, states what it depends on, and names companies by what they supply at that step. Company roles are described qualitatively and deliberately carry no market shares, revenue figures or rankings — those change faster than an explainer can, and a stale number is worse than none. Ticker links point at company pages on this site and are provided for reference only.
Nothing here is investment advice, a recommendation, or a forecast. A company named on a page about a technology is not thereby a good investment, and the chokepoints described are structural facts about supply chains rather than predictions about prices. Technology moves; where a page describes something as unresolved or in development, that was true when it was written.
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