Current QM System Benefits

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

The boards are also used to electrically connect the required leads for each part utilizing conductive copper traces. The component 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 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 real copper pads and connection traces on the board surface areas as part of the board production procedure. A multilayer board consists of a variety of layers of dielectric product 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 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 4 layer board style, the internal layers are frequently utilized to supply power and ground connections, such as a +5 V aircraft layer and a Ground airplane layer as the two internal layers, with all other circuit and part connections made on the leading and bottom layers of the board. Very intricate board designs might have a large number of layers to make the various connections for various voltage levels, ground connections, or for linking the many leads on ball grid array gadgets and other big incorporated circuit package formats.

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

The movie stack-up technique, a more recent technology, would have core material as the center layer followed by layers of pre-preg and copper product built up above and below to form the last variety of layers needed by the board style, sort of like Dagwood building a sandwich. This approach allows the maker flexibility in how the board layer thicknesses are combined to fulfill the ended up item thickness requirements by varying the variety of sheets of pre-preg in each layer. As soon as the product layers are completed, the whole stack ISO 9001 goes through 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 procedure of producing printed circuit boards follows the steps below for most applications.

The procedure of identifying products, processes, and requirements to fulfill the consumer's specifications for the board design based on the Gerber file information offered with the purchase order.

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

The conventional 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 location; newer procedures utilize plasma/laser etching rather of chemicals to remove the copper material, enabling finer line definitions.

The procedure of aligning the conductive copper and insulating dielectric layers and pressing them under heat to trigger 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 that are not to be plated through. Info on hole place and size is contained in the drill drawing file.

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

This is required 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 includes cost to the finished 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 safeguards versus environmental damage, provides insulation, protects against solder shorts, and protects traces that run between pads.

The procedure of covering the pad areas with a thin layer of solder to prepare the board for the eventual wave soldering or reflow soldering procedure that will happen at a later date after the components have actually been placed.

The process of using the markings for component designations and element outlines to the board. May be used to simply the top side or to both sides if components are installed on both top and bottom sides.

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

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

The procedure of checking for continuity or shorted connections on the boards by methods using a voltage in between numerous points on the board and determining if a present flow happens. Depending upon the board intricacy, this process might require a specially designed test fixture and test program to incorporate with the electrical test system used by the board manufacturer.