Just Simply Quality Management Systems

In electronics, printed circuit boards, or PCBs, are used to mechanically support electronic parts 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 design might have all thru-hole components on the top or element side, a mix of thru-hole and surface install on the top side just, a mix of thru-hole and surface mount elements on the top and surface mount components on the bottom or circuit side, or surface install elements on the leading and bottom sides of the board.

The boards are also utilized to electrically connect the needed leads for each element 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 designed as single agreed copper pads and traces on one side of the board only, double sided with copper pads and traces on the top 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 include a core dielectric product, 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 surfaces as part of the board production procedure. A multilayer board includes a variety of layers of dielectric product that has been fertilized with adhesives, and these layers are used 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 innovations.

In a typical four layer board design, the internal layers are typically used to provide power and ground connections, such as a +5 V plane layer and a Ground aircraft layer as the 2 internal layers, with all other See more circuit and component connections made on the leading and bottom layers of the board. Really complicated board styles might have a a great deal of layers to make the numerous connections for various voltage levels, ground connections, or for linking the many leads on ball grid range gadgets and other big incorporated circuit plan formats.

There are generally two types of product used to construct a multilayer board. Pre-preg product is thin layers of fiberglass pre-impregnated with an adhesive, and is in sheet type, typically about.002 inches thick. Core material resembles an extremely thin double sided board because it has a dielectric material, such as epoxy fiberglass, with a copper layer deposited on each side, normally.030 thickness dielectric product with 1 ounce copper layer on each side. In a multilayer board style, there are 2 methods used to develop the desired variety of layers. The core stack-up approach, which is an older innovation, utilizes a center layer of pre-preg material 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 movie stack-up technique, a newer technology, 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 variety of layers needed by the board style, sort of like Dagwood constructing a sandwich. This technique permits the producer flexibility in how the board layer thicknesses are combined to fulfill the ended up product thickness requirements by varying the number of sheets of pre-preg in each layer. Once the material layers are finished, the whole 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 manufacturing printed circuit boards follows the actions listed below for most applications.

The process of figuring out products, procedures, and requirements to meet the customer's specs for the board style based upon the Gerber file info offered with the order.

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

The conventional process of exposing the copper and other locations unprotected by the etch resist film to a chemical that gets rid of the unprotected copper, leaving the protected copper pads and traces in location; newer procedures use plasma/laser etching instead of chemicals to get rid of the copper product, permitting finer line meanings.

The procedure of lining up 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 material.

The procedure of drilling all the holes for plated through applications; a 2nd drilling procedure is utilized for holes that are not to be plated through. Details 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 required when holes are to be drilled through a copper location 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 procedure 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 applied; the solder mask secures against ecological damage, offers insulation, protects against 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 process that will take place at a later date after the components have been put.

The process of using the markings for component classifications and element details to the board. May be used to just the top or to both sides if parts are mounted on both leading and bottom sides.

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

A visual assessment of the boards; likewise can be the process of inspecting wall quality for plated through holes in multi-layer boards by cross-sectioning or other methods.

The procedure of checking for continuity or shorted connections on the boards by methods applying a voltage between numerous points on the board and figuring out if a current circulation occurs. Depending upon the board complexity, this procedure may require a specially designed test component and test program to incorporate with the electrical test system utilized by the board producer.