SMT High Density Design and DFM

SMT is becoming the dominant technology for the designing of modern day electronic products. With smaller packages, automated assembly, lower parasitics and improvement in electrical performance, many of today's products could not be produced without the use of SMT. Introducing SMT can be accomplished easily by learning where the pitfalls and issues are before you begin designing. Thereby avoiding the costly redesigns and escalated production costs to fix avoidable defects.

This one-day course is invaluable to SMT design and manufacturing. It will save countless hours by providing an understanding of what is critical and what the proper steps are to designing for assembly of successful products.

Who Would Benefit:

The course has proven to be of immense value to design, manufacturing and process engineers, project engineers, purchasing, quality and test engineers.

Course Outline:

Introduction There are new steps and standards required when designing using SMT. All the new requirements and steps must be understood to emphasize how easy it is to design and have manufacturing problems. Items discussed include:

• Terms
• Goals
• Purpose
• Dimensions
• Documents
• Design Flow Steps

Design Project Objectives
Key to successful designing is fully understanding all the needs and requirements of each design and discussing it with manufacturing. Information will include:

• Type I, II, III Assembly Processes
• Project Information Required
• Documentation
• Specifications
• Test Needs
• Fabrication
• Design Goals

Rules for Designing
The successful design is a design that goes through manufacturing with the least amount of problems and defects. In this module information helps to learn what is required to accomplish this.

• Mechanical Specs
• Tooling Holes
• Fiducials
• Panelizing
• Depanelizing
• Stencils
• Assembly Equipment
• Tape and Reels

CAE Requirements
When using SMT there are numerous options in how to design a product. But when designing a keen understanding of the impact on manufacturing is required. A lot of it starts right during the development of the schematic. Topics include:

• Essential Design Requirements for Library Standardization
• Test Requirements
• Unique SMT Packages
• Down-Loading CAE to CAD and Common Problems in Data Files

Land Pattern Rules
At the heart of the design are the land patterns used. Information explains:

How to create land patterns and how they will act during the manufacturing assembly and reflow processes. Some pattern modifications will discussed such as for wave soldering and no-clean fluxes. Pattern creation will be presented for gullwing, J lead, cylindrical, chip components, BGA and butt leads.

CAD System
The proper setup of a CAD system in the beginning to accommodate the needs of the design density and manufacturing are vital. Topics include:

• Part Centroids
• Orientation
• Silk Screens
• Stringers
• Apertures
• Gerber Outputting

Design For Testability
There are many test requirements for modern complex assemblies such as:

• Schematics and Bare Board Test
• In-circuit Test
• Bar Codes
• Edge Connectors
• Bench Level Testing
• Using Headers

Component Placement and Orientation
The density and yields are directly affected by patterns, placement and orientation. Topics covered:

• Guidelines Orientation
• Standard Density Placement Guidelines
• High Density Guidelines
• Ultra High Density Placement Guidelines
• Guidelines for design and placing Parts on the Wave Solder Side of Assemblies
• Fine Pitch Parts
• Using Sockets

Design Routing Rules and Guidelines
Trace routing density is going up sharply particularly with higher density packages and double-side mounted boards. Items discussed:

• The typical problems of routing are presented for outer and inner layers
• Proper connection to lands, using solder paste to fill holes
• Using holes in lands
• Fine Pitch package routing
• Copper thieving

PC Fabrication
There are many items critical in a design that affect the cost and ability to fabricate a design. Information presented is:

• Solder Mask Types and Clearances
• OSP coating
• Warpage Causes
• Plating Types
• Vias and Pad Sizes
• Layer Stacking Fiducial Specs
• Fabrication Panels and Materials

Documentation
Giving clear instruction for fabrication and assembly can avoid many costly mistakes. Information includes:

• Manufacturing
• Test
• Fabrication Notes and Drawings
• Sub-panels
• Films and UL Requirements

Course Materials: SMT High Density Design and DFM
Instructor: James C. Blankenhorn