Boardtoboard

Board-to-board refers to the method of electrically connecting two printed circuit boards (PCBs) that are placed in close proximity to form a single assembly. The connection is typically achieved with dedicated connectors, mezzanine interposers, or elastomeric contacts that align mating surfaces on the two boards. BTB interconnections are used when high signal density and compact form factors are required, such as in mobile devices, laptops, and industrial equipment.

BTB configurations include mezzanine connectors that stack boards in parallel, and side-by-side or vertical arrangements that enable various packaging geometries. The connector pitch commonly ranges from sub-0.8 mm to about 2.5 mm, chosen based on density, mechanical tolerances, and electrical performance. Some BTB systems employ zero insertion force or latching mechanisms to secure the connection and ensure repeatable mating.

Design considerations for board-to-board connections include precise mechanical alignment, parallelism between boards, thermal expansion compatibility, mating force, and signal integrity. High-speed or high-density applications require controlled impedance, differential pairs, and careful routing near the connector. Materials typically involve gold-plated copper contacts with insulating housings made from polymers such as PBT or LCP, and sometimes multiple contact rows for increased reliability.

Applications span consumer electronics like smartphones, tablets, and laptops; automotive infotainment; aerospace; and industrial automation. The term can also encompass flexible or rigid-flex assemblies that connect boards with bending radii or curved geometries.

Advantages of board-to-board interconnections include high interconnect density, reduced wiring complexity, and compact overall package size. Challenges include mechanical complexity, cost, and sensitivity to misalignment or thermal expansion, which require careful design and robust manufacturing processes. While many component families and application notes exist from connector manufacturers, there is no single universal standard for all BTB implementations.