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A printed circuit board (PCB) mechanically supports and electrically connects electrical or electronic components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. Components are generally soldered onto the PCB to both electrically connect and mechanically fasten them to it.
Fiberglass, or fibreglass is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet, or woven into a fabric. The plastic matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinylester—or a thermoplastic.
Epoxy refers to any of the basic components or cured end products of epoxy resins, as well as a colloquial name for the epoxide functional group. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups.
A thermosetting polymer, resin, or plastic, often called a thermoset, is a polymer that is irreversibly hardened by curing from a soft solid or viscous liquid prepolymer or resin. Curing is induced by heat or suitable radiation and may be promoted by high pressure, or mixing with a catalyst. Heat is not necessarily to be applied externally. It is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.
FR-4 is a NEMA grade designation for glass-reinforced epoxy laminate material. FR-4 is a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant (self-extinguishing).
A via is an electrical connection between layers in a physical electronic circuit that goes through the plane of one or more adjacent layers. To ensure via robustness, IPC sponsored a round-robin exercise that developed a time to failure calculator.
Filament winding is a fabrication technique mainly used for manufacturing open (cylinders) or closed end structures. This process involves winding filaments under tension over a rotating mandrel. The mandrel rotates around the spindle while a delivery eye on a carriage traverses horizontally in line with the axis of the rotating mandrel, laying down fibers in the desired pattern or angle. The most common filaments are glass or carbon and are impregnated in a bath with resin as they are wound onto the mandrel. Once the mandrel is completely covered to the desired thickness, the resin is cured. Depending on the resin system and its cure characteristics, often the rotating mandrel is placed in an oven or placed under radiant heaters until the part is cured. Once the resin has cured, the mandrel is removed or extracted, leaving the hollow final product. For some products such as gas bottles, the 'mandrel' is a permanent part of the finished product forming a liner to prevent gas leakage or as a barrier to protect the composite from the fluid to be stored.
Conformal coating material is a thin polymeric film which conforms to the contours of a printed circuit board to protect the board's components. Typically applied at 25-250 μm(micrometers) thickness, it is applied to electronic circuitry to protect against moisture, dust, chemicals, and temperature extremes.
Flat no-leads packages such as quad-flat no-leads (QFN) and dual-flat no-leads (DFN) physically and electrically connect integrated circuits to printed circuit boards. Flat no-leads, also known as micro leadframe (MLF) and SON, is a surface-mount technology, one of several package technologies that connect ICs to the surfaces of PCBs without through-holes. Flat no-lead is a near chip scale plastic encapsulated package made with a planar copper lead frame substrate. Perimeter lands on the package bottom provide electrical connections to the PCB. Flat no-lead packages include an exposed thermally conductive pad to improve heat transfer out of the IC. Heat transfer can be further facilitated by metal vias in the thermal pad. The QFN package is similar to the quad-flat package (QFP), and a ball grid array (BGA).
Electronic packaging is the design and production of enclosures for electronic devices ranging from individual semiconductor devices up to complete systems such as a mainframe computer. Packaging of an electronic system must consider protection from mechanical damage, cooling, radio frequency noise emission and electrostatic discharge. Product safety standards may dictate particular features of a consumer product, for example, external case temperature or grounding of exposed metal parts. Prototypes and industrial equipment made in small quantities may use standardized commercially available enclosures such as card cages or prefabricated boxes. Mass-market consumer devices may have highly specialized packaging to increase consumer appeal. Electronic packaging is a major discipline within the field of mechanical engineering.
IPC is a trade association whose aim is to standardize the assembly and production requirements of electronic equipment and assemblies. It was founded in 1957 as the Institute of Printed Circuits. Its name was later changed to the Institute for Interconnecting and Packaging Electronic Circuits to highlight the expansion from bare boards to packaging and electronic assemblies. In 1999, the organization formally changed its name to IPC with the accompanying tagline, Association Connecting Electronics Industries.
Microvias are used as the interconnects between layers in high density interconnect (HDI) substrates and printed circuit boards (PCBs) to accommodate the high input/output (I/O) density of advanced packages. Driven by portability and wireless communications, the electronics industry strives to produce affordable, light, and reliable products with increased functionality. At the electronic component level, this translates to components with increased I/Os with smaller footprint areas, and on the printed circuit board and package substrate level, to the use of high density interconnects (HDIs).
Fiberglass sheet laminating is the process of taking a thin fiberglass sheet and laminating it to another material in order to provide strength and support to that material.
Electronic components have a wide range of failure modes. These can be classified in various ways, such as by time or cause. Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits.
A stamped circuit board (SCB) is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or traces etched from copper sheets laminated onto a non-conductive substrate. This technology is used for small circuits, for instance in the production of LEDs.
A polymer capacitor, or more accurately a polymer electrolytic capacitor, is an electrolytic capacitor (e-cap) with a solid electrolyte of a conductive polymer. There are four different types:
Pad cratering is a mechanically induced fracture in the resin between copper foil and outermost layer of fiberglass of a printed circuit board (PCB). It may be within the resin or at the resin to fiberglass interface.
Park Electrochemical Corp, now called the Park Aerospace Corp, is a Melville, New York-based materials manufacturer for the telecommunications, Internet infrastructure, high-end computing, and aerospace industries. It produces high-technology digital and radio frequency(RF)/microwave printed circuit material products, composite materials. Its printed circuit materials are used for complex multilayer printed circuit boards and other electronic interconnection systems, such as multilayer back-planes, wireless packages, high-speed/low-loss multilayers, and high density interconnects (HDIs). Its core capabilities are polymer chemistry formulation and coating technology.
Solder fatigue is the mechanical degradation of solder due to deformation under cyclic loading. This can often occur at stress levels below the yield stress of solder as a result of repeated temperature fluctuations, mechanical vibrations, or mechanical loads. Techniques to evaluate solder fatigue behavior include finite element analysis and semi-analytical closed-form equations.
Dye-n-Pry, also called Dye And Pry, Dye and Pull, Dye Staining, or Dye Penetrant, is a destructive analysis technique used on surface mount technology (SMT) components to either perform failure analysis or inspect for solder joint integrity. It is an application of dye penetrant inspection.
References
- 1 2 IPC TM-650 2.6.25 Conductive Anodic Filament (CAF) Resistance Test: X-Y Axis https://www.ipc.org/4.0_Knowledge/4.1_Standards/test/2-6-25.pdf
- ↑ L. Zou and C. Hunt, “How to Avoid Conductive Anodic Filaments (CAF),” National Physical Laboratory. 22 Jan 2013. http://www.npl.co.uk/upload/pdf/20130122_caf_avoid_failure.pdf
- ↑ C. Tulkoff. “Design for Reliability: PCBs” North Texas IPC Designers Council. https://www.dfrsolutions.com/hubfs/Resources/services/Design_for_Reliability_PCBs.pdf?t=1514473946162
- ↑ C. Hillman. “A Novel Approach to Identifying and Validating Electrical Leakage in Printed Circuit Boards through Magnetic Current Imaging.” Proceedings from the 30th International Symposium for Testing and Failure Analysis, November 14-18, 2004 Worcester, Massachusetts. http://www.dfrsolutions.com/hubfs/DfR_Solutions_Website/Resources-Archived/Publications/2002-2004/2004_SQUID_Hillman.pdf
- ↑ S. Binfield, C. Hillman, T. Johnston, and N. Blattau, ”Conductive Anodic Filaments: The Role of Epoxy-Glass Adhesion”, DfR Solutions White Paper
- ↑ IPC TM-650 2.6.16 Pressure Vessel Method for Glass Epoxy Laminate. https://www.ipc.org/TM/2.6.16.pdf