APPLICATION
Raspberry Pi Board-to-Board Connector (CM4 / CM5)
The Raspberry Pi CM4 / CM5 compute module connects to the carrier board through two 100-pin, 0.4mm pitch board-to-board connectors from the DF40 family. It is also the part that most often stalls a custom carrier design.
How the CM4 / CM5 connectors work
Two 100-pin, 0.4mm pitch connectors sit side by side on the module, with the receptacle on the module side and the plug on the carrier, or the reverse depending on design, at a 1.5mm-class stack. The B118 series covers exactly this: 100 pins at 0.4mm from 1.5mm up to 4.0mm, so adding a heatsink or a stiffener does not force a PCB change.
Three traps in carrier design
1) Stack height: a heatsink or standoff needs a taller stack, and B118 covers six heights with a common plug. 2) Footprint and stencil: for 0.4mm at 100 pins use a 0.10–0.12mm stencil with aperture pull-back and check coplanarity before reflow. 3) Keying: when two connectors mate at once, locating pegs and keying must agree or the module will mate offset.
Replacing the DF40 family
The B118 footprint and structure follow the DF40 family, and the 100-pin part covers CM4 / CM5 carrier requirements. Build a validation board first to confirm insertion force, coplanarity and post-reflow offset.
Specifications
| Requirement | B118 option | Notes |
|---|---|---|
| CM4 / CM5 mating | 100 pins, 0.4mm, 1.5mm stack | Two connectors, receptacle on module |
| Heatsink or stiffener | 2.0 / 2.5 / 3.0mm stack | Change the receptacle only |
| HAT / expansion board | 40–80 pins, 0.4mm | Trim by signal count |
| Tall mechanical stack | BB0098 (0.8mm, 60 pins, 15mm) | Clearance for enclosure parts |
FAQ
Which connector does CM4 / CM5 use?
Two 100-pin, 0.4mm pitch board-to-board connectors from the DF40 family; B118 provides the same 100-pin layout with six stack heights from 1.5mm.
Is it a direct replacement?
The footprint follows the DF40 family and the 100-pin part covers the requirement; validate insertion force and reflow offset on a test board first.
What if the stack is too low after adding a heatsink?
One plug covers all heights, so only the receptacle changes (2.0 / 2.5 / 3.0mm) with no PCB layout change.
Are 3D models available?
Yes, STEP and 2D drawings for stack-up and interference checks.
Send us your stack-up requirement
Share board thickness, available height, channel count and environment and we will recommend and quote within 24 hours.