| Magazine: A portable enclosure used to hold PCBs or product. |
| Mask: The photographic negative that serves as the master for making thick and thin film screens. |
| Mean Time Between Failures (MTBF): The mean average time, usually in hours, that can be expected between failures an operating unit. |
| Melting Point: The temperature at which a solid becomes a liquid. |
| Mesh Size: The number of holes per linear measure in a screen printing material. |
| Micro Ball Grid Array: The process for placing an integrated circuit or other component on a multi-layer PCB using an array of extremely small solder balls (or columns) at each contact. |
| Microprocessors: Integrated circuits that contain the CPU for a computing device. |
| Microvias: Laser-created small holes, or vias. |
| Mil: Unit of length equal to 0.001 inch. |
| Mil. Std.: Military Standard, the basic military standard for reliability. |
| Minimum Conductor Width: The smallest distance between any two adjacent conductors, such as traces, in a PCB. |
| Mixed Assembly: An assembly composed of through-hole and surface mount components. |
| Motherboard: A printed circuit board for interconnecting arrays of plug-in electronic modules. |
| Multi-Chip Module Laminates: A PCB design for placing multiple integrated circuits or other components on a limited surface area. |
| Multilayer PCB: Circuit boards with three or more layers of printed circuits separated by laminate layers and bonded together with internal and external interconnections. |
