Board-to-board connectors are used to connect circuit boards and consist of pins on one board that mate with receptacles on another board. They provide multiple board connection options, ease of upgrading, and conserve space. Common applications include medical equipment, aerospace, and military systems. Board-to-board connectors can provide permanent or movable connections and use through-hole or surface mount technology depending on the application.

2. WHAT ARE BOARD TO BOARD CONNECTORS?
• Board-to-board (B2B) connectors as the name indicates
are used for connecting circuits boards together.
• Board to board connectors consist of two connectible
parts.
• One part, which typically has pins, attaches to one PCB
while the part with receptacles is mounted to another PCB.
• The circuit boards are then connected by mating to two
parts of the connector.

3. ADVANTAGES:
• Multiple add-on board options and ease of upgradeability or
accommodation of future design changes.
• Mating different combinations of headers and sockets will create
difference between-board spaces.
• Low stack heights, high I/O density and compact insulator conserve
valuable PC board space.
• Telecom switches
• Servers
• Processors
TYPICAL APPLICATIONS:
• Medical equipment
• Aerospace
• Military defense systems

4. BOARD TO BOARD CONNECTION TYPES:
Board to
Board
Permanent
Stamped
Pin
Machined
Pin
Straight
Right
Angle
Movable
Stamped
Pin
Female Male
Machine
Pin
Straight
Through
Hole
Female Male
Right Angle
Through
Hole
Female Male

5. COMPARISON:
Properties Stamped pins
Stamped and formed
pins
Machined pins
Material Brass PhB (Phosphorus Bronze)
BeCu (Beryllium
Copper)
Cost Economical Moderate cost High cost
Fatigue strength and
conductivity
Poor Better Best
Heat treatment to relax
stresses and increase
performance
Normally not done Normally not done Clips are heat treated
Electrical Conductivity %
IACS
26 15 22
Mechanical life Very low Better Best
Prevention of flux and
solder contamination
Poor Poor Best
Contact Type
Two-point
Rough Edge
Surface Contact Smooth
Edge
Truly multi Finger
contact
Reliability of connection Poor Better Best
Selective Loading Not Possible Not Possible Possible
Wastage
Cut from
Assembled
Connector So One
Pin Wastes
Cut from Assembled
Connector So One Pin
Wastes
Made after
Insulators are cut So
No wastage

6. PERMANENT CONNECTION:
• Permanent connection between two boards
can be readily achieved by soldering a
through-hole header to both the main
(mother) board and mezzanine (daughter)
board.
MOVABLE CONNECTION:
• In most board-to-board applications, design
requires that the boards are pluggable.
• The male headers in single and dual-row
configurations are mated with female sockets.
• This allows for easy replacement in the event
of board failure.

7. THROUGH HOLE BOARD-TO-BOARD
CONNECTION:
• Through-hole mounting is the process by
which component leads are placed into
drilled holes on a bare PCB.
• Through-hole components are best used
for high-reliability products that require
stronger connections between layers
• Allowing the components to withstand
more environmental stress that’s why
through-hole technology is commonly
used in military and aerospace products
that may experience extreme
accelerations, collisions, or high
temperatures.

8. SURFACE MOUNT BOARD-TO-BOARD CONNECTION:
• SMT the process by which components are
mounted directly onto the surface of the PCB
known originally as “planar mounting”
• It has become essential to PCB design and
manufacturing, having improved the quality and
performance of PCBs overall, and has reduced the
costs of processing and handling greatly.
• The key differences between SMT and through-
hole mounting are
• (a) SMT does not require holes to be drilled
through a PCB,
• (b) SMT components are much smaller, and
• (c) SMT components can be mounted on both side
of the board.
• The ability to fit a high number of small
components on a PCB has allowed for much
denser, higher performing, and smaller PCBs.

9. RIGHT-ANGLE HORIZONTAL BOARD-TO-BOARD
CONNECTION:
• For applications requiring boards to
be plugged in on a horizontal plane,
right angle sockets and headers are
used.
RIGHT-ANGLE PERPENDICULAR BOARD-TO-BOARD
CONNECTION:
• Right-angle sockets and headers can
also be used in tandem with vertical
mount sockets and headers to create
a perpendicular interconnect between
two boards.

10. LOW PROFILE BOARD-TO-BOARD
CONNECTION:
• For applications requiring boards to be mated
very closely together to save vertical space.
• The carrier socket is placed in position, allowing
the receptacles to fall into the holes in a pc
board.
• Only the shoulder of the receptacle rests on the
surface of the pc board.
• After wave soldering, the carrier is removed and
only the height of the shoulder is left above the
board. Effectively, the entire “insulator” has been
eliminated.
• Next, a male header is mated to provide for a
very tightly-spaced, pluggable board-to-board
interconnect.

11. Pitch
Mating Pin
Dia.
Straight Right Angle
Surface
Mount
Floating
Surface
Mount
2.54 mm
0.47mm ✔ ✔ ✔ ✔
0.76mm ✔ ✔ ✔ ✔
1.00mm ✔
2.00 mm 0.47mm ✔ ✔ ✔
1.778 mm 0.47mm ✔
1.27 mm 0.47mm ✔ ✔ ✔
1.00 mm 0.47mm ✔
BOARD TO BOARD CONNECTOR SIZES :

12. MORE INFORMATION ABOUT MACHINED
PINS:
• Shell or sleeve is made of brass alloy 360 ½ hard for
strength, conductive, and thermal properties.
• Press-fit assembled inside each shell is a highly reliable,
four-finger beryllium copper contact clip, which scores
the mating device lead, forming a gas-tight electrical and
mechanical connection.
• For high-temperature applications of more than 150°C,
an alternative beryllium nickel alloy is available.
• Multi-finger contact clips are superior to stamped pin
wiping connector blades because they provide multiple
points of contact to the mating pin, resulting in providing
better power and force distribution.
• Two-piece receptacle construction (shell and contact clip)
allows for cost-efficient plating combinations.
• Receptacle shells can be plated with tin for solderability.
• Contact clips can be gold-plated for optimum

13. • Author Nalin P. Sheth, MBA Harvard, is Managing Director of
Champion Electronics Pvt. Ltd., Pune, India.
• Champion Electronics is serving electronics industry all over the
world from 1975.
• Contact Details :
• Email : sales@champelec.com
• Ph: +91-8928502180.
• Website : www.champelec.com