Circuit Board Fabricators Case Study
Circuit Board Fabricators, Inc. (Source: Operations management; Chase et.al.)
Circuit Board Fabricators, Inc. (CBF), is a small manufacturer of circuit boards located in California near San Jose. Companies such as Apple Computer and Hewlett-Packard use the company to make boards for prototypes of new products. It is important that CBF give quick and very-high-quality service. The engineers working on the new products are on a tight schedule and have little patience with sloppy work or missing delivery dates.
Circuit boards are a rigid flat surface where electronic components are mounted. Electronic components such as integrated circuits, resistors, capacitors, and diodes are soldered to the boards. Lines called “traces” are etched on the board and electronically connect the components. Since the electronic traces cannot cross, holes through the circuit board are used to connect traces on both sides of the boards, thus allowing complex circuits to be implemented. These boards often are designed with 40-50 components that are connected through hundreds of traces on a small four- by six-inch board.
CBF has developed a good business plan. They have four standard size board configurations and have automated much of their process for making these standard boards. Fabricating the boards requires CBFs numerically controlled (NC) equipment to be programmed. This is largely an automated process that works directly from engineering drawings that are formatted using industry standard codes.
Currently, the typical order is for 60 boards. Engineers at customer companies prepare a computer-aided design (CAD) drawing of the board. This CAD drawing precisely specifies each circuit trace, circuit pass-through holes, and component mounting points on the board. An electronic version of the drawing is used by a CBF process engineer to program the NC machines used to fabricate the boards.
Due to losses in the system, CBF has a policy of increasing the size of an order by 25 percent. For example, for a typical order consisting of 60 boards, 75 boards would be started through the process. Fifteen percent of the boards are typically rejected during an inspection that occurs early in the manufacturing process and another 5 percent of the remaining boards are rejected in final test.
BOARD FABRICATION PROCESS
CBF purchases circuit board blanks from a vendor. These boards are made from woven fiberglass cloth that is impregnated with epoxy. A layer of copper is laminated onto each side to form a blank board. The blank board comes from the vendor trimmed to the standard sizes that CBFs numerically controlled equipment can handle.
The following is a description of the steps involved in processing an order at CBF:
Order acceptance.