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RoHS compliant PCB

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RoHS compliant PCB | 2 February, 2006


I have some questions about material used in PCB for RoHS compliancy. It seems to be fuzzy between may manufacturer. Here are my questions:

1) What is the recommended material for lead-free assembly? 2) What's the difference between FR4 High Tg 170 and 180? 3) What is the definition of High Tg? 4) Do you know a website where I can see a chart with different material with their respective caracteristics? 5) What can I expect on the final price? 6) Is it possible to take different material instead of FR-4?

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RoHS compliant PCB | 2 February, 2006

Here you see a link (recently posted by John S) where you can find interesting infos that could answer part of your questions.


This message was posted via the Electronics Forum @

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Yash Sutariya


RoHS compliant PCB | 6 February, 2006

Hi, I authored the presentation so I may be able to help you out with your Q's.

1. IPC is in draft stage for 4 new material specs. These are in the presentation. I would focus on IPC 4101/ 121 and /124. Match your current Tg requirement to the Tg ranges in one of these two specs and that will be your new lead free material spec.

2. The real difference is the Td of these materials. 170Tg FR4 has a Td of about 300. The new 180Tg lead free materials have Td values of 340 or higher.

3. Tg is glass transition temperature, or the point at which the material starts to gel. Td is the glass decomposition temperature, or the point at which is begins to degrade from a weight-loss perspective.

5. Pricing is most affected on 2, 4, and 6 layer boards for the base material upcharge. There are midgrade materials available to help mitigate this if you spec in /121 material.

Please feel free to email me at if you have any additional questions. Thanks!

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