Posts Tagged ‘Lead Free’

Simple Yield Improvement. (Part 2)

Sunday, January 6th, 2013

In the previous post we discussed what happens to the printed circuit board structure when it is heated. We discussed how different materials expand at different rates and the effect the expansion rates have on the warp and twist of a Printed Circuit Board (PCB). We also discussed how moisture absorption can increase the degree of warp and twist and the adverse effect it has on assembly yields and potential field failures. We also discussed how dry baking removes moisture from the PCB and how it minimizes if not eliminates potential problems.

In this post we shall discuss the stabilizing effect that (more…)

Simple Yield Improvement. (Part 1)

Monday, December 31st, 2012

Over the past 15 years we have seen some very amazing advancements in technology. Our electronic devices have become smaller, faster and more powerful. The capabilities of these new devices have brought science fiction to life for many of us. What the common consumer does not realize is that these advancements have occurred in a more destructive Lead-Free assembly process. Lead Free assembly methods consisting of higher assembly temperatures (around 260ºC) for longer dwell times at temperature along with a smaller processing window for success. The assembly methods today are challenged to not only maintain yields but to improve them. All the while cutting costs where ever possible. The desire to cut cost is where we see the result of unintended consequences.

I have been asked repeatedly by customers for my opinion on methods to improve yields. I evaluate designs and work with designers and assemblers on solutions to help them improve yields. This includes in process and post process yields. In other words build it right the first time and make sure it lasts in the field. A common question I am asked by customers is…

What is the one thing that we can do that can  improve our yields?

The answer is very simple… (more…)

What damage does the assembly process do to a pcb? (part 2)

Friday, August 19th, 2011

In part 1 of this blog post I commented upon the affect the assembly process has upon a printed circuit board. The assembly temperatures applied do in fact burn away the epoxy of the FR-4 composite material. The higher the temperature the faster the rate of burn. I touched upon the relation ship between the glass transition temperature (Tg), decomposition temperature (Td) and the Maximum continuous Operating Temperature (MOT). There is another gauge that can be used to help a designer or contract assembler understand this point and that is the Time to delamination test. These are referred to as either the T260 or T288 tests.

What is the T260/T288 Time to Delamination? This is a test defined by (more…)

What damage does the assembly process do to a pcb? (part 1)

Wednesday, August 17th, 2011

A colleague contacted me the other day with a topic that would make an excellent post on this blog.

“How can we solder boards with a Tg of 180°C or even 200°C at temperatures of 225-245°C without damaging the board?  Even with leaded boards the peak reflow temperatures are way above the board’s Tg.  How is this possible?”

The answer is simple. Every time a printed circuit board is exposed to soldering temperatures it becomes damaged. This is the case not only for Lead-Free soldering applications but also for eutectic soldering consisting of tin-lead.

Tg is one of several parameters to be aware of. In the case of Tg most designers refer to the value as (more…)

OrmeSTAR Ultra

Saturday, September 12th, 2009

OrmeSTAR Ultra is a new surface finish which has recently been introduced into the market. I read about this finish in a press release published at www.pcb007.com I am currently managing the installation and qualification of the chemical process at Electropac Co., Inc. located in Manchester NH USA. Their URL is www.electropac.com This shall be the first installation in the United States in a production environment. Ultra is classified as an Organic Metal-based Nanofinish and can be considered a Green process. More information is available from the manufacturer of OrmeSTAR Ultra at www.enthone.com The OrmeSTAR Ultra fact sheet can be downloaded from Enthone or through the link below… (more…)

Why can’t I use FR4 with Lead Free Soldering.

Saturday, January 17th, 2009

You can build a printed circuit board and solder it through a lead free soldering temperatures. It is not advisable! I know some designers that use standard FR4 for lead free soldering applications. The designs are simple single and double sided boards. The companies that they work for have done the due diligence to prove out their design and manufacturing process. On moderate to complex designs they specify lead free soldering compliant laminates in place of FR4. The compliant laminates are much more expensive than standard FR4. They made the upfront investment system by doing the testing and evaluating to save money down the road. They know what they can get away with and have the test data to prove it. However, the results are specific to their designs and their assembly process. When in doubt, play it safe and specify lead free soldering compliant laminate. In order to justify the cost of the more expensive laminate you need to understand what happens to the material at high temperatures.

The main challenge faced by a laminate system is (more…)

RoHS vs. Lead Free Assembly

Saturday, January 17th, 2009

It is easy to mis-interpret the relationship between RoHS and Lead Free Assembly. Lead Free Assembly has been around for decades in limited applications. RoHS came about when the European Union passed a directive known as WEEE. WEEE or Waste of Electrical and Electronic Equipment (2002/96/EWG) regulates the end of life disposal and recycling of electrical waste. The legislation states that producers are responsible for waste and financing its collection. Users from private households should be allowed to recycle products free of charge. To reduce recycling costs the restricted or banned materials, manufacturers are striving to remove these substances from their product. This is where RoHS comes in.

RoHS or Restriction of Hazardous Substances (2002/95/EWG) prohibits the use of the following substances: (more…)