Ways In Which Quality Management Systems Are Built

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

The boards are likewise used to electrically link the required leads for each part utilizing conductive copper traces. The element pads and connection traces are etched from copper sheets laminated onto a non-conductive substrate. Printed circuit boards are created as single agreed copper pads and traces on one side of the board only, double agreed copper pads and traces on the top and bottom sides of the board, or multilayer styles with copper pads and traces on top and bottom of board with a variable variety 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 etched away to form the actual copper pads and connection traces on the board surface areas as part of the board production process. A multilayer board includes a variety of layers of dielectric material that has actually been fertilized with adhesives, and these layers are utilized to separate the layers of copper plating. All of these layers are lined up then 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 common 4 layer board style, the internal layers are often utilized to supply power and ground connections, such as a +5 V plane 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 complicated board designs may have a a great deal of layers to make the different connections for different voltage levels, ground connections, or for linking the lots of leads on ball grid range devices and other big incorporated circuit plan formats.

There are usually two types of product utilized to build a multilayer board. Pre-preg material is thin layers of fiberglass pre-impregnated with an adhesive, and is in sheet type, generally about.002 inches thick. Core product is similar to a very thin double sided board in that it has a dielectric material, such as epoxy fiberglass, with a copper layer deposited on each side, normally.030 thickness dielectric material with 1 ounce copper layer on each side. In a multilayer board design, there are 2 approaches used to develop the desired number of layers. The core stack-up method, which is an older technology, uses a center layer of pre-preg material with a layer of core material above and another layer of core material listed below. This mix of one pre-preg ISO 9001 layer and 2 core layers would make a 4 layer board.

The movie stack-up method, a newer innovation, would have core product as the center layer followed by layers of pre-preg and copper material built up above and listed below to form the final number of layers required by the board style, sort of like Dagwood constructing a sandwich. This approach permits the manufacturer flexibility in how the board layer thicknesses are integrated to satisfy the ended up item density requirements by differing the number of sheets of pre-preg in each layer. When the material layers are finished, the entire stack is subjected to 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 steps below for the majority of applications.

The process of identifying materials, processes, and requirements to satisfy the customer's requirements for the board design based on the Gerber file details provided with the purchase order.

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

The standard process of exposing the copper and other locations unprotected by the etch resist movie to a chemical that eliminates the unprotected copper, leaving the protected copper pads and traces in place; newer processes utilize plasma/laser etching instead of chemicals to remove the copper material, allowing finer line meanings.

The process of lining up the conductive copper and insulating dielectric layers and pushing them under heat to activate the adhesive in the dielectric layers to form a solid board material.

The procedure of drilling all the holes for plated through applications; a 2nd drilling process is utilized for holes that are not to be plated through. Details on hole place and size is contained in the drill drawing file.

The procedure of using 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 needed when holes are to be drilled through a copper area however the hole is not to be plated through. Avoid this procedure if possible since it includes expense to the completed board.

The process of applying a protective masking material, 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 protects against environmental damage, provides insulation, protects versus solder shorts, and secures traces that run in between pads.

The procedure of covering 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 parts have been put.

The process of using the markings for component classifications and component describes to the board. Might be used to simply the top side or to both sides if components are installed on both leading and bottom sides.

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

A visual inspection of the boards; likewise 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 checking for connection or shorted connections on the boards by means applying a voltage in between numerous points on the board and identifying if an existing flow happens. Relying on the board intricacy, this procedure may require a specifically designed test component and test program to incorporate with the electrical test system utilized by the board producer.