Features of QM Systems in Modern Businesses

In electronics, printed circuit boards, or PCBs, are used to mechanically support electronic elements which have their connection leads soldered onto copper pads in surface area mount applications or through rilled holes in the board and copper pads for soldering the element leads in thru-hole applications. A board design may have all thru-hole parts on the leading or element side, a mix of thru-hole and surface area install on the top just, a mix of thru-hole and surface install components on the top and surface install elements on the bottom or circuit side, or surface install components on the leading and bottom sides of the board.

The boards are also utilized to electrically connect the required leads for each component using conductive copper traces. The element pads and connection traces are engraved 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 only, double sided with copper pads and traces on the leading and bottom sides of the board, or multilayer designs with copper pads and traces on the top and bottom of board with a variable number of internal copper layers with traces and connections.

Single or double sided boards consist of a core dielectric material, such as FR-4 epoxy fiberglass, with copper plating on one or both sides. This copper plating is engraved away to form the actual copper pads and connection traces on the board surfaces as part of the board production procedure. A multilayer board includes a variety of layers of dielectric product See more that has been impregnated with adhesives, and these layers are used to separate the layers of copper plating. All of these layers are lined up and then bonded into a single board structure under heat and pressure. Multilayer boards with 48 or more layers can be produced with today's innovations.

In a normal four layer board style, the internal layers are typically used to supply power and ground connections, such as a +5 V airplane layer and a Ground airplane layer as the 2 internal layers, with all other circuit and part connections made on the top and bottom layers of the board. Very complex board designs might have a large number of layers to make the numerous connections for various voltage levels, ground connections, or for linking the numerous leads on ball grid variety gadgets and other large incorporated circuit bundle formats.

There are generally two kinds of material utilized to build a multilayer board. Pre-preg product is thin layers of fiberglass pre-impregnated with an adhesive, and remains in sheet form, normally about.002 inches thick. Core material is similar to a very thin double sided board because it has a dielectric material, such as epoxy fiberglass, with a copper layer deposited on each side, usually.030 thickness dielectric product with 1 ounce copper layer on each side. In a multilayer board design, there are two methods used to build up the desired number of layers. The core stack-up technique, which is an older innovation, uses a center layer of pre-preg material with a layer of core material above and another layer of core product listed below. This mix of one pre-preg layer and 2 core layers would make a 4 layer board.

The movie stack-up method, a more recent innovation, would have core product as the center layer followed by layers of pre-preg and copper material developed above and below to form the final number of layers required by the board style, sort of like Dagwood constructing a sandwich. This method enables the producer flexibility in how the board layer densities are combined to fulfill the completed product density requirements by differing the number of sheets of pre-preg in each layer. As soon as the product layers are completed, the whole stack goes through heat and pressure that causes 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 actions below for a lot of applications.

The procedure of figuring out products, processes, and requirements to meet the client's specifications for the board design based on the Gerber file info offered with the purchase order.

The procedure of transferring the Gerber file information for a layer onto an etch withstand film that is placed on the conductive copper layer.

The traditional process of exposing the copper and other areas unprotected by the etch withstand movie to a chemical that removes the unprotected copper, leaving the safeguarded copper pads and traces in location; more recent procedures utilize plasma/laser etching rather of chemicals to remove the copper product, enabling finer line definitions.

The procedure of aligning the conductive copper and insulating dielectric layers and pushing them under heat to trigger the adhesive in the dielectric layers to form a strong board product.

The process of drilling all the holes for plated through applications; a second drilling procedure is used for holes that are not to be plated through. Info on hole place and size is consisted of in the drill drawing file.

The procedure of applying copper plating to the pads, traces, and drilled through holes that are to be plated through; boards are put in an electrically charged bath of copper.

This is needed when holes are to be drilled through a copper area but 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 procedure of using a protective masking material, a solder mask, over the bare copper traces or over the copper that has had a thin layer of solder applied; the solder mask secures against environmental damage, supplies insulation, safeguards against solder shorts, and secures traces that run 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 process that will occur at a later date after the elements have actually been put.

The process of using the markings for component classifications and part describes to the board. May be applied to just the top side or to both sides if components are mounted on both leading and bottom sides.

The process of separating several boards from a panel of similar boards; this procedure also permits cutting notches or slots into the board if required.

A visual evaluation of the boards; also can be the procedure of examining wall quality for plated through holes in multi-layer boards by cross-sectioning or other methods.

The process of looking for continuity or shorted connections on the boards by means applying a voltage between numerous points on the board and determining if an existing circulation takes place. Relying on the board intricacy, this process may require a specifically developed test component and test program to integrate with the electrical test system used by the board producer.