SFF-TA-1002 is a card edge connector specification used for OCP NIC 3.0 cards, EDSFF drives and DC-SCM modules. It defines four sizes (1C, 2C, 4C and 4C+) and two connector types, Type 1 and Type 2. The type decides how freely pins can be reassigned and how grounds are handled. This guide explains the difference and lists the ratings to check.
In short:
- SFF-TA-1002 is a multi-lane, protocol-agnostic card edge connector. It is published by the SNIA Small Form Factor technology group.
- Sizes: 1C (56 contacts), 2C (84), 4C (140) and 4C+ (168).
- Type 1 is a discrete pin interface where pins can be repurposed. Type 2 has a fixed mix of high-speed pairs, power and management, and may tie grounds together inside the connector.
- The draft figures below are from a working revision, so check the current release before design.
For the OCP NIC 3.0 use of this connector, see our OCP NIC 3.0 connector guide.
What the Specification Defines
The draft specification describes an unshielded card edge input/output connector that mates with an add-in card. It comes in four orientations: straight, right angle, straddle mount and orthogonal. One manufacturer says the connector pitch is 0.6 mm and that the pinout supports EDSFF, PCIe, OCP NIC and other standards, aiming to consolidate fragmented pinouts and speeds so designers can multi-source the part.
Speed claims vary by source and revision. TE describes its connectors as 28G NRZ and 56G PAM-4, with a roadmap to 56G NRZ and 112G PAM-4. The draft specification text refers to signaling up to 112 or 128 GT/s PAM4, and its revision marks leave the top figure unclear. Orthogonal versions are limited to 2.5 to 32 GT/s NRZ.
The Four Sizes
All sizes use a ground-signal-signal-ground-signal-signal-ground (GSSGSSG) pattern:
- 1C: 56 contacts, up to 18 differential pairs.
- 2C: 84 contacts, up to 26 pairs.
- 4C: 140 contacts, up to 44 pairs.
- 4C+: 168 contacts, up to 52 pairs.
Keys keep cards aligned. The 2C, 4C and 4C+ sizes use keys for fine alignment and to prevent insertion rotated by 180 degrees. The 1C uses internal side walls and is keyed by the form factor and host. The 1C, 2C and 4C must be aligned through the form factor and the host to work with 4C+ cards.
Type 1 vs Type 2
- Type 1: a discrete pin interface. Power and management pins can be repurposed for high-speed pairs, and the reverse. It supports asymmetric transmission. It is not available for orthogonal connectors. Labeling it "T1" is optional.
- Type 2: mixes defined high-speed pairs, power and management signals. Defined grounds may be joined inside the connector. It must be labeled "T2."
In practice, Type 1 gives the design more freedom in how pins are used. Type 2 fixes the pin roles. If a datasheet does not state the type, ask which one the part is.
Grounding
Advanced grounding contacts make first and break last. They carry the power ground return current and provide a path for ESD discharge.
Ratings in the Draft Specification
- Voltage: 29 V per pin.
- Current: 1.1 A per pin static, with up to 3 A for 100 microseconds or less and derating for longer durations.
- Temperature: -40 to 85 degrees C.
- Mating cycles: grade A is 200, grade B is 100 and grade C is 50.
- Insertion force: at most 1.1 N per pin pair.
- Wipe: minimum effective wipe of 2.00 mm for tin-tin and 0.40 mm for gold-gold.
- Board thickness (straddle mount): 1.57, 1.93, 2.36, 2.55 and 3.05 mm nominal options, each with its own tolerance and offset.
Selection Checklist
- Size and type: confirm 1C, 2C, 4C or 4C+ and Type 1 or Type 2 against the form factor you are building to.
- Orientation: straight, right angle, straddle mount or orthogonal.
- Speed: ask for tested channel data at your signaling rate, not only the connector's claimed generation.
- Mating cycle grade: A, B or C.
- Board thickness: the straddle-mount option has to match your PCB stack.
- Power pins: 1.1 A per pin means high-power cards need several power pins.
- Plating: gold or tin affects the wipe and the cycle rating.
Frequently Asked Questions
What is SFF-TA-1002 used for? It is the connector family behind OCP NIC 3.0, EDSFF drives and DC-SCM modules.
What do 4C and 4C+ mean? 4C has 140 contacts and 4C+ has 168. The 4C+ adds extra contacts for sideband signals.
Is Type 2 better than Type 1? Neither is better. Type 1 lets pins be reassigned, and Type 2 has fixed roles.
What is the pitch? One manufacturer states 0.6 mm. The draft specification we checked does not state a pitch.
Where to Go Next
Sources
- SFF-TA-1002 draft specification (SNIA): sizes, contacts, types, grounding, ratings and mating data. A draft revision.
- TE Sliver card edge connectors (Power Systems Design): pitch, speeds and purpose of the standard.