Printed Circuit Design & Fab - June 2008 - (Page 25)

DFA / dFt typically an arbitrary file format that contains manufacturing relevant data such as where the actual components will be placed on the board and whether certain locations will not be populated. It is not possible to rely on the layout data directly to determine the pick up point and component rotation, as this might not have an accurate relation to the actual part. Manufacturing assembly machines need the center of the part as its pick up point, which isn’t always coincident with the origin of the CAD land pattern. Likewise for rotation, the CAD land pattern zero rotation may not match the part zero rotation, and so parts get placed with an incorrect orientation. Being able to consistently normalize part locations and rotations significantly reduces errors in production. FiGurE 3 illustrates a typical land pattern as defined in a CAD system. In this case, the center of pin 1 defines the origin for the component, and therefore it is this point that is used as the component position locator in the layout. The grey centroid marker has been added to the data to indicate a normalized origin and rotation that can be used to calculate the correct board location in x-y coordinates. Typically, the paste layers in the CAD data are either a copy of the copper pads associated with a part, or are a simple reduction in size of the copper pads. This capability does not give enough flexibility to the stencil creation process to yield acceptable results. While these area reduction rules can work for some parts, more complex paste apertures are needed to create optimum solder goals. For example, notched rectangles or ‘home plate’ apertures are routinely used for two-pin chip components. An example of a complex pad that has been defined for a stencil on a simple two-pin chip component appears in FiGurE 4. There is little relationship between the copper pads of the land pattern and the actual stencil pad required. Summary Neutralizing all the disparate source data into a single data format that can be used by manufacturing while eliminating redundancies is the key to accelerating design data from concept to manufacturing. This data can then be used as a collaboration medium between engineering, PCB layout, and manufacturing, balancing the unique requirements of each group and providing the ability to focus analysis and feedback, ensuring that the resultant product meets the quality and cost targets. These tools and the common data set provide the underlying method to communicate product-specific data from design to manufacturing, and will help manufacturers meet the increasing challenges they face in bringing products profitably to market. pcd&f Mark lainG is product marketing manager for Mentor Graphics and can be reached at mark_laing@mentor.com. “Ventec laminate has been a tremendous asset in Titan PCB East’s ability to provide a high quality, high reliability lead free product to today’s time critical, cost sensitive market. Ventec VT-47 provides superior peel strength, high Td, Z-axis stability, thermal reliability, surface quality and inventory selection all in the same package. The fact that this is provided in a cost competitive manner is icing on the cake. Ventec is not just a player in the game, they are a top performer. The addition of VT-90 polyimide materials to the FR-4 offerings make Ventec a force to be reckoned with in the future.” Mike Berg, President and CEO, Titan PCB East – Amesbury, MA “When using the VT-47 and VT-481 materials, we have found above average drill and scoring characteristics without experiencing the fracturing and haloing associated with other well-known lead free comparable phenolic resin systems.” John Gratton Engineering Manager Century Circuits – Toronto, ON “We have been very pleased with the quality, service, performance, and consistency of the Ventec materials for almost two years now. I would not hesitate to recommend Ventec VT-47 to our customers as a reasonably priced alternative for lead free assembly.” Robert E. Welch Process Engineering Manager Waytec Electronics Corp. – Lynchburg, VA “The family of Ventec laminates has made an improvement in our processing of multilayer circuits. The materials exhibit very good consistency. Our quality with the performance of these laminates.” department is very satisfied Jim King Process Engineer Philway Products – Ashland, OH 16 Hunt Rd. South • Amesbury, MA 01913 • (978) 388-9610 • (978) 388-5339 fax • www.globallaminates.com Sales reps and distributors wanted: email Bruce at bhurley@globallaminates.com JUNE 2008 Global Laminates Inc. printEd circuit dESign & fAB 25 http://www.globallaminates.com http://www.globallaminates.com

Table of Contents Feed for the Digital Edition of Printed Circuit Design & Fab - June 2008

Printed Circuit Design & Fab - June 2008 Contents Our Line Market Watch Around the World Happenings ROI Tip Jar Interconnect Strategies Final Finish Forum DFA/DFT Signal Integrity From the Field DFA Fab Basics Drill Off the Shelf Marketplace Ad Index BGA Bulletin

Printed Circuit Design & Fab - June 2008

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