Organizations May Gain From Utilizing a Quality System

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 install applications or through rilled holes in the board and copper pads for soldering the part leads in thru-hole applications. A board style might have all thru-hole components on the leading or element side, a mix of thru-hole and surface install on the top just, a mix of thru-hole and surface area install elements on the top side and surface install components on the bottom or circuit side, or surface mount components on the leading and bottom sides of the board.

The boards are also utilized to electrically link the required leads for each component using conductive copper traces. The element pads and connection traces are etched from copper sheets laminated onto a non-conductive substrate. Printed circuit boards are developed as single agreed copper pads and traces on one side of the board just, 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 number of internal copper layers with traces and connections.

Single or double sided boards include a core dielectric product, 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 surface areas as part of the board manufacturing process. A multilayer board consists of a number of layers of dielectric material that has actually 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 technologies.

In a normal four layer board design, 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 part connections made on the leading and bottom layers of the board. Extremely intricate board designs may have a large number of layers to make the different connections for various voltage levels, ground connections, or for linking the numerous leads on ball grid variety gadgets and other big incorporated circuit package formats.

There are typically two types of product used to build a multilayer board. Pre-preg material is thin layers of fiberglass pre-impregnated with an adhesive, and is in sheet kind, normally about.002 inches thick. Core product is similar ISO 9001 consultants to a really thin double sided board because it has a dielectric product, such as epoxy fiberglass, with a copper layer transferred on each side, usually.030 density dielectric product with 1 ounce copper layer on each side. In a multilayer board style, there are 2 methods utilized to develop the wanted number of layers. The core stack-up method, which is an older technology, utilizes a center layer of pre-preg material with a layer of core material above and another layer of core material below. This combination 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 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 required by the board design, sort of like Dagwood constructing a sandwich. This approach enables the manufacturer versatility in how the board layer densities are combined to satisfy the completed product thickness requirements by differing the variety of sheets of pre-preg in each layer. When the material layers are finished, the entire stack is subjected to 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 manufacturing printed circuit boards follows the actions below for most applications.

The procedure of determining products, processes, and requirements to fulfill the customer's requirements for the board style based upon the Gerber file info provided with the purchase order.

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

The conventional procedure of exposing the copper and other locations unprotected by the etch withstand movie to a chemical that gets rid of the unguarded copper, leaving the safeguarded copper pads and traces in location; newer procedures utilize plasma/laser etching rather of chemicals to get rid of the copper product, permitting finer line meanings.

The process of aligning the conductive copper and insulating dielectric layers and pressing them under heat to activate the adhesive in the dielectric layers to form a solid board product.

The procedure of drilling all of the holes for plated through applications; a second drilling procedure is utilized for holes that are not to be plated through. Information on hole place and size is included 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 needed when holes are to be drilled through a copper location however the hole is not to be plated through. Prevent this procedure if possible due to the fact that it adds cost 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 had a thin layer of solder used; the solder mask safeguards versus environmental damage, provides insulation, safeguards versus solder shorts, and safeguards traces that run between pads.

The process of coating 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 procedure of using the markings for component designations and component outlines to the board. May be applied to simply the top side or to both sides if parts are installed on both leading and bottom sides.

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

A visual evaluation 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 methods.

The process of checking for continuity or shorted connections on the boards by means applying a voltage in between various points on the board and identifying if an existing flow occurs. Depending upon the board intricacy, this procedure may need a specially created test fixture and test program to integrate with the electrical test system used by the board maker.