Determining Break Even Volume Boundaries for Custom Sensor PCB Integration
Discrete sensor chip-down integration breaks even above fifteen thousand units where bill-of-materials savings overcome tooling and test fixture outlays.
Castellated Carrier
Edge Connection
A standardized packaging format utilizes semi-plated holes along the perimeter of a daughterboard module to allow direct surface mounting to a motherboard. This castellated carrier design removes the need for separate pins or headers, creating a lower profile assembly. The semi-cylindrical recesses provide a visual and physical region for solder fillet formation during reflow.
Assembly Integration
The alignment of the castellated carrier with the host board pads requires precise optical placement to prevent offset joints. Solder paste is deposited on the landing pads of the motherboard, and the module is placed on top of these deposits. During the reflow cycle, molten solder drawn up the copper-lined channels forms the mechanical and electrical connection.
The vertical ascent of the solder fillet within the castellation provides a highly visible joint that can be verified through automated visual methods.
Inspection Criteria
Dimensional stability remains critical because PCB routing tolerance directly affects the depth and shape of the cut-away holes. Variations in routing can lead to incomplete castellations or copper burrs that impede proper coplanarity. These defects create uneven seating of the module during assembly and result in open circuits.
Soldering Dynamic
Thermal mass must be balanced during profiling to ensure that both the module and motherboard reach solder liquidus simultaneously.