FAQ’s About Moisture Control

Moisture in either prepreg or processed inner layers may impact lamination results in a variety of ways that may be detrimental both to the fabrication and in-use performance of finished MLB’s.  In epoxies it may reduce Tg of the cured material by hydrolysis.  In polyimide or other systems where chemical reaction per-se does not occur, moisture may result in delamination or blistering during post-processing or finishing.  This article discusses the issues for various material sets and suggests methods for reducing moisture prior to lamination.

“Back to the Future” – Foil Lamination for the 21st Century

The use of foil lamination in HDI designs has surged in recent years because options are available for very thin layers suitable for high interconnect density combined with laser drilling for very small diameter holes. This article discusses some of the materials available as well as issues that might be encountered in PWB fabrication and/or Assembly.

Drilling Defects – Causes and Solutions

This note talks about common drilling defects, their possible causes, and makes suggestions for reducing or eliminating the conditions. Originally assembled by Arlon’s Harv Beaman, this note provides ‘hands-on’ suggestions to optimize drilling.

Glass Compression

When fiberglass bundles are too close to copper surfaces there is the chance of increased incidence of shorts and current leakage. This short article makes concrete suggestions to eliminate this undesirable phenomenon.

Measuring and Understanding Tg (Glass Transition Temperature)

Tg is often used as a proxy value for “plated through hole reliability”. This useful property may be measured in more than one way, and each one because it measures a different property, will give a somewhat different result. Some materials do not exhibit Tg values, and others require specific tests to generate meaningful results. This tutorial article discusses both methods and significance of Tg testing.

Moisture Absorption of Polyimide MLB’s

Because polyimide materials absorb moisture more quickly and to a higher nominal level than epoxies, there is added risk for moisture related delamination or blistering in downstream processing and/or assembly. This work describes testing done to determine the rate at which moisture is absorbed under various conditions, providing a guideline for when the material will exceed the 0.2% “critical level” requiring drying before subsequent processing.

NASA Volatiles Testing

Many or Arlon’s products have been tested by NASA to ASTM E-595-93 (Standard Method
for Total Mass Loss and Collected Volatile Condensable Materials from Outgassing in a Vacuum Environment) as a requirement for approving these materials for Space Applications. This note discusses the significance of the testing and lists the Arlon products that have been tested with their results.

Rheology – Materials in Motion

Understanding rheology on a practical and theoretical basis replaces some of the magic in the lamination process with science. Applying this science to the multilayer lamination process can mean the difference between a robust process in the middle of a process window and one that can occasionally drift out of control. This article looks at the measurement of melt viscosity and application of the data obtained to the MLB Process.

Low Flow Prepreg – Defining the Beast

This article discusses the basics of low flow technology, featuring measurement and test, a discussion of melt rheology and provides an introduction to the fundamental nature of the low flow “beast.” Of particular interest is discussion of the IPC Low Flow test and its ramifications.

Low Flow Prepreg – Taming the Beast

This article, the second in a pair of articles on Low Flow materials talks to the practical issues of designing and using low flow materials in various applications such as rigid-flex and heat-sink bonding.  The focus is on understanding how material properties interact with PWB processing.

Continuous Operating Temperature

This article discusses the Continuous Operating Temperature at which a particular material can operate without undue deterioration for a long period of time.

Recommendations for Assembly – 85NT

This article provides recommendations for storage, drying, and assembly of printed wiring boards containing Arlon 85NT.

Prepreg Shelf Life

Arlon EMD prepreg is certified to IPC-4101 and meets the shelf life requirements stated in IPC 4101 paragraph 3.17.