Ken,
You will still need to look at the percentage of thermal expansion in
the z-axis. If you pick a material with poor (high) z-axis thermal
expansion then you could still have significant problems.
Thanks
Tony Cosentino
Tekelec - PCB Design Engineer
[log in to unmask]
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Ken Patel
Sent: Wednesday, February 23, 2005 12:06 PM
To: [log in to unmask]
Subject: Re: [LF] RoHS compliance PCB
Rick and others,
Many of our boards are very high layer counts and they are generally
between
18 and 26 layers.
I am thinking about Tg of 170C and Td of 350C. What is your take on Tg
and Td for such high layers count?
Re,
Ken Patel
-----Original Message-----
From: Smith, Rick [mailto:[log in to unmask]]
Sent: Thursday, February 17, 2005 6:38 AM
To: (Leadfree Electronics Assembly Forum); Ken Patel
Subject: RE: [LF] RoHS compliance PCB
Ken,
Check with your process guys. I have found increasing laminate
decomposition temperature to above 330 C is required, and moving to 170
Tg laminate is unnecessary and a cost adder with respect to 4/8 layer
computer boards.
Laminates with Tg 145, 150 survive LF BGA rework provided the
decomposition temperature is >330 C.
Anyone else working on laminates have input?? Please coment.
thanks
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Ken Patel
Sent: Wednesday, February 16, 2005 5:06 PM
To: [log in to unmask]
Subject: [LF] RoHS compliance PCB
All,
I have heard that Fab Houses are moving directly to Halogenfree process,
skipping middle step knowing that Halogenfree is next in line to be
implemented. As our current fabs are built using laminate made of Tg of
170 C or more with Nickel Gold surface finish, do you see any problem?
Do we have to worry besides updating the fab notes asking for RoHS
compliance? We expect fab house to build products based on impedance
requirement. Any comments, suggestion?
Re,
Ken Patel
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