Stencil Technology and Design Workshop


Presented by Bill Coleman, Ph.D., Photo Stencil.

Course Description


This workshop provides information on stencil printing performance and how stencil technology and design influences printing performance. Much of the data presented was generated during print performance studies at independent test laboratories. Solder volume and solder volume dispersion are the key data used to predict print performance and overall SMT assembly yields/defect rates.

Stencil designs for a variety of applications will be reviewed in detail. SMT Assembly Tools (Wave Solder Pallets, Process Carriers etc.) and SMT Assembly Inspection Tools will also be covered.

This proactive workshop will be presented in one day from 9:00 AM to 4:00 PM, including a lunch break. The class is held at the Photo Stencil, Colorado Springs facility and will include a tour of the facility. A complete workbook of all information including reference information will be provided to all attendees.

All workshops are held on Friday and the 2011 schedule is as follows:
  • January 21
  • February 25
  • March 25
  • April 9
  • May 20
  • June 17
  • July 15
  • August 19
  • September 16
  • October 14
  • November 25
  • December 16

Who Should Attend


This is a hands-on workshop for process engineers, quality control engineers, supervisors, managers, and technicians who are involved with solder-paste screen printing, process control, solder paste selection, and optimizing the assembly process.

Morning Topics


Company Overview

Introductory section provides a brief overview of the company and its history since 1979. Company mission statement, product technology, quality control systems, special design projects, manufacturing operations, and product review will be presented.

Print Process and Stencil Technology

Overall review of important printing process parameters. The following topics will be covered:
  • Board variables
  • Solder paste variables
  • Printer and stencil variables
  • Stencil designs will be reviewed in detail covering the technologies of Electroformed Stencils, Laser Stencils and Chem-Etch Stencils
  • The Print Area Ratio and its influence on solder paste release
  • Aperture design guidelines and a stencil performance hierarchy
Stencil Design and Stencil Applications

This section will review the following stencil applications:
  • No-clean aperture design
  • SMT / through-hole mixed technology
  • Flip-chip / SMT mixed technology
  • Step stencil designs
  • BGA and µBGA stencil designs
  • BGA repair tools
  • BGA package reballing tools
  • Glue stencil design and applications
  • Squeegee blade considerations
  • Ball drop stencils and tools (wafer level and package level)
  • Wafer bumping stencils

Afternoon Topics


Lead-Free Process Impacts

This section covers an overview of process changes and considerations in lead-free manufacturing. The July 2006 deadline to become WEEE and RoHS compliant for suppliers to European markets has quietly come and gone with little notoriety. Many suppliers have lead-free capabilities, however, they are waiting for their customers to place orders. Topics include:
  • Environmental concerns
  • Legislation
  • Replacement alloys
  • Stencil design considerations
  • Case study comparison of stencil technologies and lead-free printing
Intrusive Reflow for Tin/Lead and Lead-Free Solder

This section reviews in detail the stencil designs for printing solder paste in and around through-hole locations for reflow as an alternative to wave solder of through-hole parts. Examples of three different stencil designs will be shown along with a spreadsheet for determining stencil design to provide sufficient solder volume. Printer set up to optimize the amount of paste hole-fill is reviewed. X-rays of reflowed through leads are also presented.

Print Performance Studies Comparing Electroform, Laser, Laser with Electropolish, and Laser with Electropolish and Nickel plating.

This session is an in-depth review of available stencil technologies. Identical stencils were produced using the same Gerber file with a wide range of apertures. Visual appearance and solder paste volume were gathered and stencils were ranked according to their performance. Utilizing this study, stencil selection guidelines are offered based on area ratio, aperture size and foil thickness.

Lead-Free Solder Paste Volume Print Performance Comparisons for Electroformed and Laser Stencils. (Independent Stencil Study)

This is a summary of a recent study performed at Universal Instruments on a series of 12 stencils (5 Electroform and 7 Laser) comparing the print performance for lead-free and tin/lead solder pastes. Stencils were provided by the five leading stencil manufacturers, including Photo Stencil. An Open Yield Analysis for Array Devices, developed by Universal Instruments, is also used to correlate stencil performance directly to SMT assembly yields. A grading system is used to rank the stencil performance.

Solder Paste Printing Problems and Solutions.

This session reviews issues related to printing equipment, tools, methods, materials and SMT assembly failure modes. Solutions are developed to solve some of these problems.

Facility Tour

Costs

  • Existing Photo Stencil Customers: FREE (contact your Technical Sales Representative)
  • Non-Photo Stencil Customers: $1000 (full credit for this amount is offered against stencil or squeegee blade sales within 60 days of attending this workshop)

Information


Download a Flyer for the workshops here
Download the registration form here
Contact Bill Coleman at (719) 535-8528 or at bcoleman@photostencil.com