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Minimum Tg for LeadFree board.

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Minimum Tg for LeadFree board. | 20 August, 2009

What is the minimum Tg for FR4 board to consider as Lead Free board?

My issue is, I do not know what is the web for the V-Score for a FR4 Tg 180.

I use to use a FR4 Tg 140 and there is no problem with it, but since we convert to Lead Free and the board house use a Tg 180 for our board and we issue with the depanelize.

Board house said if we convert to Lead Free then they have to use a higher Tg board which a harder material.

My question are: 1. What are the min. Tg FR4 meet lead free? 2. What is the web dimension for the V-Score with finish board 0.062" and Tg 180 material?

Please help.

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Minimum Tg for LeadFree board. | 21 August, 2009


To Start Min Tg is just a portion of picking a lead free material, the other is Td.

We recommend the following to our Customers.

2-8 layer 150 Tg. Min. / 340 Td. 8-Up. 170-180 Tg.Min. / 340 Td.

The above recommendations have been used by many EMS companies in the Midwest.

regarding Scoring Web thickness on .062 boards.

.015 +/-.003 web. works for most companies, especially if you have a PCB VCut Depaneler/Separator if not you may want to drop the web down to .013 +/-.003. Their are several companies that make Vscore depaneler equipment just google.

My disclosure - I currently sell for a US owned-Taiwan based board house and run our Midwest Sales office.

I hope the info above helps.

Best Regards, Mike Dupont Active Sales Associates,Inc.

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Minimum Tg for LeadFree board. | 21 August, 2009


I suggest you visit the website, where I found these information :


"...Tg is not a good indicator of a materials’ ability to be suitable for Pb free assembly. While a material with a higher Tg is considered to be more thermally resistant, new Pb Free FR4 materials with high or low Tg can be Pb free capable. One of the major differences between Pb free FR4 and standard FR4 is the Td (Decomposition Temperature). However, Td is only one “indicator” of being Pb free capable. Pb free FR4 materials have a Td around 350°C It is also important for a material to be able to achieve a T288 (Time to Delamination) value of at least 5 minutes. Boards should also be subjected to multiple Pb free reflow cycles to verify resistance to delamination and blistering..."

Hi ghepo

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Minimum Tg for LeadFree board. | 21 August, 2009


if your going to try to push your book, why don't you disclose that the web site your pushing is yours.


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Minimum Tg for LeadFree board. | 21 August, 2009

Dear Mike,

because that site and handbooks are property of many hands and because I work in a multinational company as manager of a PCB quality dept. Therefore, be mistaken for a "guru" in this major website, is not my purpose.

Anyway, thanks for your kind interest.

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Minimum Tg for LeadFree board. | 22 August, 2009


Minimum Tg for LeadFree board. | 23 August, 2009

I think you're getting steered in the wrong direction, with the exception of DaveF's link. By the way, I'm a PCB fabricator, just to avoid any backlash.

IPC 4101 is the IPC guideline for raw materials. It has 6 slash sheets for lead-free capable materials, which fall into 3 main classifications. The materials you are most used to seeing fit within IPC 4101/126 and /129 (typically 370HR, IS410, SM750, IT188, etc..). The lowest slash sheets are /101 and /121, with the primary thermal description change being a min Td of 310C. These materials aren't commonly found in the states, but perhaps one day we will get there.

Going back to your scoring issue. As BoardHhouse mentioned, a 0.015" web is typical for 0.062". While you can drop it to 0.012", you risk having your arrays fall apart on you during assembly, especially if you have heavier components on them. If it were me, I'd first verify that you're actually getting 0.015" web to begin with. The reason is that these 180Tg/340Td materials are phenolic materials, which are not just harder, but more brittle. When we first started using them, the surface would look like a zipper after scoring due to the material fracturing as the blade went through. An easy way to avoid this was by reducing the depth of the blade, which increases the web thickness. However, this results in issues like those that you are seeing. At the end of the day, we ended up changing our scoring parameters like RPM and feed, as well as shortening the life of our scoring blades.

If the web checks out, then it would be wise to invest in depaneling equipment such as those made by CAB and FKN.

At the end of the day, these are just bandaids to deal with materials that cost a lot of money but still have a lot of issues. We're seeing more and more customers convert to the middle IPC categories of /99 and /124, which tend not to be phenolic cured materials. This thread is getting long enough so I won't get into more details. We did a webinar on these materials (beneftis, etc.) that you might want to spend 30 minutes to look at. It's at You may find it helpful. Thanks!

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Minimum Tg for LeadFree board. | 29 August, 2009

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