Benefits of Quality Management Systems in Contemporary Organisations
In electronic devices, printed circuit boards, or PCBs, are used to mechanically support electronic elements which have their connection leads soldered onto copper pads in surface install applications or through rilled holes in the board and copper pads for soldering the component leads in thru-hole applications. A board design may have all thru-hole components on the top or part side, a mix of thru-hole and surface area install on the top side only, a mix of thru-hole and surface area install parts on the top side and surface mount components on the bottom or circuit side, or surface area install components on the leading and bottom sides of the board.
The boards are likewise used to electrically connect the needed leads for each part using conductive copper traces. The component pads and connection traces are etched from copper sheets laminated onto a non-conductive substrate. Printed circuit boards are developed as single sided with copper pads and traces on one side of the board just, double agreed copper pads and traces on the leading and bottom sides of the board, or multilayer styles with copper pads and traces on top and bottom of board with a variable number of internal copper layers with traces and connections.
Single or double sided boards include a core dielectric material, such as FR-4 epoxy fiberglass, with copper plating on one or both sides. This copper plating is etched away to form the real copper pads and connection traces on the board surfaces as part of the board production process. A multilayer board includes a number of layers of dielectric product that has actually been impregnated with adhesives, and these layers are utilized to separate the layers of copper plating. All of these layers are lined up and after that bonded into a single board structure under heat and pressure. Multilayer boards with 48 or more layers can be produced with today's technologies.
In a typical 4 layer board style, the internal layers are typically used to supply power and ground connections, such as a +5 V plane layer and a Ground plane layer as the two internal layers, with all other circuit and component connections made on the top and bottom layers of the board. Extremely complex board designs might have a large number of layers to make the numerous connections for different voltage levels, ground connections, or for connecting the many leads on ball grid variety gadgets and other big incorporated circuit bundle formats.
There are usually two kinds of material utilized to construct a multilayer board. Pre-preg material is thin layers of fiberglass pre-impregnated with an adhesive, and is in sheet kind, generally about.002 inches thick. Core material resembles a really thin double sided board in that it has a dielectric material, such as epoxy fiberglass, with a copper layer deposited on each side, generally.030 thickness dielectric product with 1 ounce copper layer on each side. In a multilayer board design, there are 2 methods used to develop the desired variety of layers. The core stack-up technique, which is an older technology, uses a center layer of pre-preg product with a layer of core material above and another layer of core product below. This mix of one pre-preg layer and two core layers would make a 4 layer board.
The film stack-up approach, a newer innovation, would have core product as the center layer followed by layers of pre-preg and copper material developed above and listed below to form the last number of layers required by the board design, sort of like Dagwood developing a sandwich. This method allows the manufacturer flexibility in how the board layer thicknesses are integrated to satisfy the completed item density requirements by differing the number of sheets of pre-preg in each layer. As soon as the material layers are completed, the entire stack undergoes heat and pressure that triggers the adhesive in the pre-preg to bond the core and pre-preg layers together into a single entity.
The process of producing printed circuit boards follows the steps below for most applications.
The process of identifying materials, processes, and requirements to meet the client's specs for the board style based on the Gerber file details offered with the purchase order.
The process of transferring the Gerber file data for a layer onto an etch withstand movie that is put on the conductive copper layer.
The traditional procedure of exposing the copper and other locations unprotected by the etch withstand film to a chemical that eliminates the unprotected copper, leaving the protected copper pads and traces in place; newer procedures use plasma/laser etching instead of chemicals to get rid of the copper material, allowing finer line definitions.
The process of aligning the conductive copper and insulating dielectric layers and pushing them under heat to activate the adhesive in the dielectric layers to form a strong board material.
The process of drilling all the holes for plated through applications; a second drilling procedure is utilized for holes ISO 9001 Certification Consultants that are not to be plated through. Info on hole location and size is consisted of in the drill drawing file.
The process of applying copper plating to the pads, traces, and drilled through holes that are to be plated through; boards are positioned in an electrically charged bath of copper.
This is required when holes are to be drilled through a copper area however the hole is not to be plated through. Prevent this process if possible due to the fact that it adds expense to the completed board.
The process of using a protective masking product, a solder mask, over the bare copper traces or over the copper that has actually had a thin layer of solder used; the solder mask secures against ecological damage, offers insulation, protects against solder shorts, and safeguards traces that run in between pads.
The procedure of coating the pad areas with a thin layer of solder to prepare the board for the ultimate wave soldering or reflow soldering procedure that will take place at a later date after the components have actually been put.
The procedure of applying the markings for element classifications and component outlines to the board. May be applied to just the top side or to both sides if parts are installed on both top and bottom sides.
The process of separating several boards from a panel of identical boards; this procedure likewise enables cutting notches or slots into the board if required.
A visual inspection of the boards; likewise can be the procedure of inspecting wall quality for plated through holes in multi-layer boards by cross-sectioning or other approaches.
The procedure of checking for connection or shorted connections on the boards by methods using a voltage between various points on the board and determining if an existing flow takes place. Relying on the board intricacy, this process may require a specifically created test component and test program to incorporate with the electrical test system used by the board producer.