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HomeProductsConnectors, InterconnectsCard Edge Connectors - Edgeboard Connectors346-040-556-878
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346-040-556-878 - EDAC Inc.

Manufacturer Part Number
346-040-556-878
Manufacturer
EDAC Inc.
Allelco Part Number
98D-346-040-556-878
Warranty
1 Year Allelco Warranty - Find out more
Stock Status:
33,300 pcs available, New & Original
Parts Description
CONN EDGE DUAL FMALE 40POS 0.125
Package
Box
Data sheet
346-040-556-878.pdf

Environmental Information

EDAC REACH.pdf
RoHs Status
ROHS3 Compliant
Compare
Our certification
In stock: 33300
  • Unit Price: $13.241
  • Subtotal: $0.00

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Quantity Unit Price Ext. Price
1+ $13.241 $13.24
The above prices does not include taxes and freight rates, which will be calculated on the order pages.

Specifications

346-040-556-878 Tech Specifications
EDAC Inc. - 346-040-556-878 technical specifications, attributes, parameters and parts with similar specifications to EDAC Inc. - 346-040-556-878

Product Attribute Attribute Value
Manufacturer EDAC Inc.
Termination Rows 2
Termination Solder
Series 346
Read Out Dual
Pitch 0.125" (3.18mm)
Package Box
Operating Temperature -40°C ~ 105°C
Number of Rows 2
Number of Positions/Bay/Row 20
Number of Positions 40
Mounting Type Board Edge, Straddle Mount
Product Attribute Attribute Value
Material - Insulation Polyester Thermoplastic
Gender Female
Flange Feature Top Mount Opening, Threaded Insert, 4-40
Features Card Extender, Card Guides
Contact Type Cantilever
Contact Material Copper Alloy
Contact Finish Thickness 10.0µin (0.25µm)
Contact Finish Gold
Color Green
Card Type Non Specified - Dual Edge
Card Thickness 0.054" ~ 0.070" (1.37mm ~ 1.78mm)
Base Product Number 346-040

Environmental & Export Classifications

ATTRIBUTE DESCRIPTION
RoHs Status ROHS3 Compliant
REACH Status REACH Unaffected
ECCN EAR99
HTSUS 8536.69.4040

Frequently Asked Questions(FAQ)

What card thickness range is compatible with the Mercury United Electronics 346-040-556-878, and how does this specification affect PCB design?
The 346-040-556-878 accommodates card thickness between 0.054" and 0.070" (1.37mm to 1.78mm). This range is critical for PCB layout because the connector's dual-row cantilever contact design relies on consistent card engagement. If your PCB thickness falls below 1.37mm, the 346-040-556-878 contacts may not achieve full compression, reducing contact force and risking intermittent connections. Conversely, thickness exceeding 1.78mm can cause contact wear or insertion force to exceed design limits. FR-4 material is typically 0.062" (1.57mm) for 2-layer boards, which falls safely within the 346-040-556-878 range. For multilayer designs or custom substrate materials, verify your final thickness during prototype stages.
How does the 0.125" pitch on the 346-040-556-878 compare to standard 0.100" pitch connectors in terms of signal integrity and crosstalk?
The 346-040-556-878 uses 0.125" (3.18mm) pitch, which provides 25% greater spacing than the industry-standard 0.100" pitch found in many Eurocard and VME backplane connectors. This larger pitch on the 346-040-556-878 reduces capacitive coupling between adjacent signal traces routed from the connector pads, lowering crosstalk in parallel signal groups. The trade-off is reduced connector density—the 346-040-556-878's 40-position dual-edge configuration occupies approximately 5" of board edge length. For high-speed differential pairs (>100 MHz), the 346-040-556-878's pitch advantage becomes measurable; simulations show approximately 5–8 dB lower crosstalk compared to 0.100" pitch variants in similar impedance environments. If your application requires >64 signals in a single connector, the 346-040-556-878's pitch may necessitate a secondary connector or alternative architecture.
What is the expected contact lifespan for the 346-040-556-878 under repeated insertion and removal cycles?
The 346-040-556-878 is rated for 50 mating cycles under typical laboratory conditions (defined as insertion and full withdrawal). This reflects the durability of the cantilever contact design and gold plating (10.0µin / 0.25µm thickness) on the copper alloy substrate. In field applications with card extender or hot-swap configurations, actual lifespan depends on contact pressure, environmental contamination, and insertion force consistency. The gold finish on the 346-040-556-878 provides corrosion resistance in humid or salt-spray environments (REACH unaffected status supports this), extending usable life compared to bare copper variants. If your design requires >50 cycles, consider conformal coating on the PCB assembly to reduce oxidation of solder joints around the 346-040-556-878 termination rows, or specify a variant with thicker gold plating.
Can the 346-040-556-878 be used in applications requiring conformal coating, and will coating affect contact performance?
The polyester thermoplastic insulation material on the 346-040-556-878 is compatible with common conformal coatings (acrylic, urethane, and silicone-based formulations). However, coating thickness around the connector edge should be carefully controlled. Coatings exceeding 0.005" (0.127mm) near the cantilever contacts of the 346-040-556-878 can reduce contact pressure by restricting normal spring deflection, increasing contact resistance. Best practice involves masking the 346-040-556-878 edge contact area during coating application or applying coating before connector installation. The 346-040-556-878's gold plating provides inherent protection against humid corrosion, so conformal coating is optional unless your operating environment includes aggressive chemical exposure or temperature cycling below -40°C in high-humidity conditions.
How should termination vias be sized and routed from the 346-040-556-878 solder pads to minimize signal reflections?
The 346-040-556-878 has two termination rows with 20 positions per row, spanning approximately 2.5" along the board edge. Via placement directly beneath solder pads introduces stub lengths that can cause reflections on high-frequency signals. For clock or differential pair signals routed from the 346-040-556-878, delay the via penetration by 0.050"–0.100" from the pad edge, allowing the trace to establish controlled impedance before transitioning to internal layers. Via diameter should be 0.010"–0.012" with 0.005" clearance to adjacent traces to maintain impedance consistency. The dual-row configuration of the 346-040-556-878 makes ground return paths critical—allocate at least two ground positions on the 346-040-556-878 (typically positions at the ends of each row) for reference planes. Simulations using 50-ohm transmission line models show that stub lengths exceeding 0.150" on the 346-040-556-878 can introduce >10% amplitude ripple at 100 MHz.
What are the dimensional clearances required for the 346-040-556-878's top-mount flange and threaded inserts when specifying mounting hardware?
The 346-040-556-878 features top-mount flange openings and 4-40 threaded inserts for mechanical stabilization. The flange requires approximately 0.25" clearance above the PCB surface for standard M3 or #4-40 mounting hardware. Threaded inserts on the 346-040-556-878 accept 4-40 screws; do not over-torque beyond 5 in-lbs, as this can damage the polyester thermoplastic housing of the 346-040-556-878 or strip threads. When specifying card guides or extender mechanisms with the 346-040-556-878, verify that guide rails do not interfere with the dual-edge card geometry. The 346-040-556-878 accommodates straddle-mount configurations where the card rests between upper and lower guide surfaces; ensure symmetrical support to prevent uneven contact pressure across the 40 positions.
How does the dual-row configuration of the 346-040-556-878 affect trace routing density on the PCB?
The 346-040-556-878 presents a 2-row by 20-position arrangement, requiring routing from both the top and bottom edges of the connector footprint. Unlike single-row edge connectors, the 346-040-556-878's dual configuration creates a routing bottleneck if both rows carry high-speed signals. Optimal trace routing from the 346-040-556-878 typically requires Layer 1 (top) and Layer 2 (bottom) escape routing before transitioning to internal layers through vias. With 0.125" pitch on the 346-040-556-878, trace width of 0.008"–0.010" and spacing of 0.008"–0.012" are achievable with standard PCB fabrication tolerances. For designs requiring >30 high-speed signals from the 346-040-556-878, implement a breakout region extending 0.25"–0.50" perpendicular to the card edge to allow fan-out before signal bundling on internal layers.
What is the contact resistance specification for the 346-040-556-878, and how does it affect power distribution designs?
The 346-040-556-878 datasheet does not publish explicit contact resistance limits, but gold-plated cantilever contacts on copper alloy typically exhibit 5–15 milliohms per contact under nominal insertion force. In power distribution scenarios where the 346-040-556-878 carries >1 ampere per signal line, estimate 0.01 ohms per connection and verify voltage drop across the connector path. For example, 2 amperes through a 346-040-556-878 contact path yields approximately 20 millivolts drop. Parallel multiple positions on the 346-040-556-878 for high-current rails to distribute current and reduce localized heating. The -40°C to +105°C operating range of the 346-040-556-878 may introduce 20–30% contact resistance variation at temperature extremes; if your power delivery tolerances are <50 mV, perform thermal modeling or prototype testing with the 346-040-556-878 in your specific current configuration.
What environmental protection does the 346-040-556-878 provide in marine or outdoor applications, and how does gold plating thickness factor into corrosion resistance?
The 346-040-556-878 features 10.0µin (0.25µm) gold plating over copper alloy, providing resistance to corrosion in humid environments. The REACH unaffected status and RoHS3 compliance of the 346-040-556-878 indicate the absence of restricted substances like cadmium or lead, but 0.25µm gold plating is classified as thin for outdoor marine exposure. In salt-spray environments, the 346-040-556-878's gold layer may develop pitting after 100–200 hours of continuous exposure without additional protection. For marine applications, specify conformal coating on the assembled 346-040-556-878, ensure drainage holes near the connector to prevent water pooling, and consider periodic maintenance intervals. The polyester thermoplastic housing of the 346-040-556-878 resists UV degradation better than ABS alternatives, supporting longer outdoor lifespan. If your design demands extended marine service, consult accelerated corrosion testing data with your specific 346-040-556-878 supplier or specify a higher gold-plating variant.
How should card retention or extraction force be validated when integrating the 346-040-556-878 into field-removable module designs?
The 346-040-556-878 is designed for card extender and straddle-mount configurations, supporting field-accessible modules. Standard insertion force for the 346-040-556-878 typically ranges from 40–80 pounds total across all 40 contacts, depending on card thickness and contact cleanliness. Extraction force should be approximately 70–80% of insertion force to prevent accidental ejection while allowing manual removal. When designing card guides or mechanical carriers for the 346-040-556-878, include anti-wiping features (guides that align the card perpendicular to the connector before contact) to minimize side-loading that can damage the cantilever contacts. Test prototypes of your 346-040-556-878 assembly across the full card thickness range (0.054"–0.070") to confirm repeatability; if extraction force drops below 50% of insertion force after 10 cycles, contact quality or guide alignment on the 346-040-556-878 may be compromised.
What grounding strategy is recommended for the 346-040-556-878 in mixed-signal designs to minimize EMI?
The 346-040-556-878 dual-row configuration supports allocation of ground pins at strategic positions for EMI containment. Best practice involves reserving positions 1, 10, 11, and 20 on the 346-040-556-878 as ground reference points, creating a shield-like distribution across the 40-position span. These ground positions should be connected to a local ground plane beneath the PCB escape region and tie to system ground with via clustering (3–4 vias per position minimum). In mixed-signal designs, separate analog and digital signal groups routed from the 346-040-556-878 to distinct power domains on the backplane; the 346-040-556-878's large 0.125" pitch provides sufficient spacing for this segregation without crosstalk coupling. Clock or high-slew-rate digital signals from the 346-040-556-878 should be flanked by ground positions within one contact distance (0.125") to establish controlled return paths and reduce far-field radiation.
Are there thermal considerations for high-density applications using multiple 346-040-556-878 connectors in parallel?
The 346-040-556-878 operating range extends from -40°C to +105°C, rated for ambient conditions without self-heating correction. When deploying multiple 346-040-556-878 connectors in parallel (e.g., for backplane or multi-module systems), contact resistance heating becomes cumulative. If three 346-040-556-878 connectors each carry 1 ampere across 30 active positions, estimated dissipation is approximately 0.9–1.4 watts per connector. For sealed or enclosed backplane designs, ensure airflow over the 346-040-556-878 termination rows or implement thermal vias and copper pours on the PCB to conduct heat away from the edge connector area. Under sustained high-current conditions, the junction temperature of the 346-040-556-878 polyester insulation can approach 110–115°C, which approaches the material's glass transition region. For applications exceeding 0.5 amperes per position on the 346-040-556-878, perform thermal FEA analysis or prototype validation to confirm safe operating margins.

Parts with Similar Specifications

The three parts on the right have similar specifications to EDAC Inc. 346-040-556-878

Product Attribute 346-040-556-808 346-040-556-807 346-040-556-858 346-040-556-812
Part Number 346-040-556-808 346-040-556-807 346-040-556-858 346-040-556-812
Manufacturer EDAC Inc. EDAC Inc. EDAC Inc. EDAC Inc.
Number of Positions - - - -
Pitch - - - -
Card Type - - - -
Termination - - - -
Contact Material - - - -
Gender - - - -
Features - - - Simultaneous Sampling
Material - Insulation - - - -
Color - - - -
Base Product Number - DAC34H84 MAX500 ADS62P42
Contact Finish Thickness - - - -
Read Out - - - -
Mounting Type - Surface Mount Through Hole Surface Mount
Package - Tape & Reel (TR) Tube Tape & Reel (TR)
Contact Finish - - - -
Flange Feature - - - -
Series - - - -
Card Thickness - - - -
Number of Positions/Bay/Row - - - -
Number of Rows - - - -
Contact Type - - - -
Termination Rows - - - -
Operating Temperature - -40°C ~ 85°C 0°C ~ 70°C -40°C ~ 85°C

346-040-556-878 Datasheet PDF

Download 346-040-556-878 pdf datasheets and EDAC Inc. documentation for 346-040-556-878 - EDAC Inc..

Datasheets
346-040-556-878 Drawing.pdf 346,396 Series Ordering Guiide.pdf
Environmental Information
EDAC REACH.pdf

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    Sep 22, 2026

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    Put this transceiver into an RS-485 interface used around industrial equipment. Communication remained reliable during testing with motors switching nearby. Good result for the replacement board.

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    Purchased for a Cyclone III development project. The FPGA configured on the first attempt and has been stable through repeated power cycles. No problems with the I/O we are using.

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    Used this rectifier in a high-current power supply repair. Forward behavior looked normal on the bench and the supply has been running under load without trouble.

  • Retr***UWorks
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    Needed the exact ST10F269Z2Q6 for servicing an older control unit. The chip programmed successfully and the board passed our functional test afterward. Much easier than redesigning around a newer MCU.

  • Andr***PCBLab
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    I needed this ADC for an older data acquisition board. Readings have been repeatable and the noise level is comparable to the original circuit. Happy with the purchase.

  • Leat***O'Keefe
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    one of my hobbies is skydiving. and when i'm skydiving this works great.

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    Great low-power MCU for portable equipment. Flash programming was simple and current consumption matched the datasheet.

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346-040-556-878 Image

346-040-556-878

EDAC Inc.
98D-346-040-556-878

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