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PCB AssemblyMarsden Smith is a contract electronic manufacturing services company providing PCB assembly services for a wide range of companies including - Defence, Gaming, Education and Medical industries. Printed circuit board surface mount methods were first used in the nineteen sixties, they became more widespread during the early nineteen eighties and then became the norm by the mid nineteen nineties. The electrical components were redesigned so that they had small metal tabs that could be mounted an soldered directly on to the surface of the PCB. Components also became much smaller and the practice of placing components on both sides of the circuit board became more common which allowed the creation of much higher circuit densities.  ElectronicsPrinted circuit boards, or PCB's, are used to electrically connect electronics components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive material (substrate). A PCB that has been fitted with electronic components is known as a printed circuit assembly (PCA) but can also be called a printed circuit board assembly (PCBA).  MunufactureMarsden Smith is well equipped to deliver a comprehensive and personal PCB assembly service within electronics manufacturing tailored to suit your business neeeds. We have a highly trained and multi-skilled workforce combined with a range of technology and systems to provide the very highest quality of PCB assembly.  BristolPCB Assembly. During the last few decades, PCB assembly has rapidly increased to become to standard way of creating reliable elctrical circuits. This is because PCBs are highly reliable and they are also much cheaper and faster for high-volume production. Within the PCB assembly industry the IPC organization sets the majority of the electronics industry's PCB design, PCB assembly, and quality control needs are set by standards. The conductive layers during the PCB assembly are usually made of very thin copper foil, the insulating layers are laminated together using epoxy resin prepreg. The PCB assembly is then coated with a solder mask usually green in color. There are various dielectrics that can be used to provide different insulating properties and this is purely dependant on the requirement of the specific circuit. Normally the printed circuit boards are made by bonding a layer of copper over the entire substrate, this is known as creating a blank PCB, then the unwanted copper is removed by a process known as etching. This process leaves behind just the copper traces that are needed. Some types of PCBs are made by adding traces to the bare substrate which is usually acieved by a complex process of multiple electroplating. The method used in manufacturing PCB's will usually depends upon whether the PCB is required for production or if it required as a sample for testing or a prototype.  PCBPCB Assembly. Once the printed circuit board (PCB assembly) has been completed the electronic components must be attached to the board, these form a functional printed circuit assembly or PCA. These completed assemblies are also know as a PCB assembly (PCBA). The electronic components are placed on pads or lands on the surface of the PCB assembly and are fixed in place with a molten metal solder. Printed circuit boards that are intended for extreme environments often have a protective coating known as a conformal coating, this protective coating is applied by either sprying or dipping the PCB after the components have been attached by soldered. The protective coat helps to prevent corrosion, loss of current due to leakage currents and short circuiting due to condensation or contamintion of other conductable materials. The first types on conformal coating were acieved by applying wax to the PCB assembly where as more modern conformal coatings are acieved by dipping the completed boards in to diluted solutions of polyurethane, acrylic, epoxy, silicone rubber or other non degradable compounds. There is a disadvantage of using conformal coats to protect the printed circuit boards and this is that once the coating has been applied it is extremely difficult to carry out repairs or modifications to the boards. PCBs can be extremely sensitive to static electricity and these types of board need to be placed in antistatic bags for transportation and storage. These sensitive boards should only be handled by someone that has been correctly earthed to ensure that no build up of static electricity has occured. Electronic components that have been attached to a PCB can be damaged or destroyed by improper handling of the board, normally through the transmission of an accumulated static charge. Even blank PCBs can sometimes be static sensitive, conductive traces being used have now become so fine that it is possible to damage the etch or create a break in the circuit with a static charge, this is more likely to occur on more rare and expensive types of PCB such as MCMs and microwave PCBs. Some types of printed circuit boards know as a laminated PCB assembly and have trace layers inside the PCB, these can also be known as multi-layer printed circuit boards. These types of PCB assembly is formed by bonding separately etched boards together, the boards used in this type of construction are very thin.  |
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