Ask the Experts
March 17, 2008 - Updated
March 17, 2008 - Originally Posted

Concerns with HDI

We are about to introduce HDI (High Density Interconnection Boards) in our production processes. What are the main causes for concern regarding:
  • Assembly process
  • Reflow profiles

J. R.

Expert Panel Responses

High Density typically infers higher mass, higher complexity and higher cost. Higher Mass and Higher complexity in a standard convection process can create challenges relative to temperature saturation, peak temperatures on smaller parts etc. The process I would suggest that will provide absolute control and protection against excessive over temperature and saturation would be a modern Vapor Phase process. Less expensive to run than convection systems and proven by the world's largest manufacturing companies to provide better yields in HDI assemblies.

Allen W. Duck
ATEK llc
Allen Duck is a 20-year Electronics Industry veteran with Global experience in multiple fields of technology and management. He started A-Tek in 2006 to provide a sales and service channel for international equipment companies wishing to offer value based solutions to USA companies.

Depending on the type of solder paste and flux chemistry that you will be using and footprint, material of construction and type of components that you will be assembling, the reflow profile concerns are ramp up, soak time and cool down. Most solder paste manufacturers will provide a nominal reflow profile that you can tweak to fit your particular PCB and component mix. If you are concerned about reflow issues and looking for a wider process window, I would recommend that you look at the possibility of using nitrogen atmosphere in your reflow furnace, with a maximum oxygen level of 1000 ppm in the reflow zone.

Gregory Arslanian
Global Segment Manager
Air Products & Chemicals, Inc.
Mr. Arslanian has been involved in electronics packaging processing and equipment since 1981 including flipchip, TAB, wirebonding and die attach. Current responsiblities include R&D, applications, marketing and customer interaction.

Take a look at Introduction to High Density Interconnection Substrates and Microvia Technologies authored by Happy Holden, TechLead Corp.

Marc Peo
Heller Industries Inc.
Mr. Peo has been with Heller Industries for over 20 years and has been President for the past 8 years. Marc has authored several industry articles on Soldering, Flux collection, nitrogen use and Lead Free conversion.
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