Electronics Forum | Mon Dec 31 08:51:58 EST 2001 | davef
Warp depends on: * How close the board gets to its Tg during the solder cycle (the closer you get to the Tg the worse the warp gets) * Amount of copper on each side and the balance between the two * Thickness of the board * Overall length x width * T
Electronics Forum | Mon Mar 03 13:22:20 EST 2003 | MA/NY DDave
Hi I see David F already gave a good answer. The basic advantage, if you can afford it, is a more stable PCB during the soldering process. Higher Tg enables this. Also some materials serve to match CTEs (coefficient of thermal expansion) a bit bett
Electronics Forum | Wed May 28 08:25:08 EDT 2003 | davef
That's what we do [no more than three reworks or mods]. Your "four reworks permissable" was probably based on the 55110 five thermal cycles, counting wave soldering as the first cycle. How do you plan to keep track of each of those rework actions?
Electronics Forum | Wed Jul 09 16:01:10 EDT 2003 | russ
Mike, the one pad that is "small" definitely appears to be over etching (It looks like it was supposed to be much larger). What is the dims of this little bugger as compared to the Gerber? i would also tend to believe that there probably is some mask
Electronics Forum | Mon Oct 13 17:50:30 EDT 2003 | davef
IPC-7530 "Guidelines for Temperature Profiling for Mass Soldering Processes (Reflow & Wave)" As you observe, the temperature you measure will depend on what you are measuring. For instance: * Hottest temperature in the oven - air in the oven * Hott
Electronics Forum | Sun Nov 30 08:53:15 EST 2003 | davef
IPC-6012A finds "circuit repairs" as acceptable in Class 1, 2, and 3 only "As agreed by user and supplier." So, it is your call, basically. Generally these repairs, if done properly, are reliable. See IPC-7721, 5.2.3, for conductor repair by welding
Electronics Forum | Wed Feb 02 22:10:30 EST 2005 | T2
Higher Tg values are only one thing to look out for. Two other things that are very important to watch are the Td or Decomposition Temperature (the temperature that the epoxy actualy starts to break down), and the CTE for the material. Some Tg 14
Electronics Forum | Wed Oct 26 10:40:43 EDT 2005 | patrickbruneel
Jimmy, We've been soldering tin plated components and Ni/Sn (100% Tin) boards with leaded solder in the 80's in hirel and military applications. We never experienced reliability issues with the mechanical or electrical properties of the solder joint
Electronics Forum | Fri Mar 03 16:05:42 EST 2006 | Chris
Hi, Anyone ever perform a DOE on prepreg glass bundle direction or glass bundle grain and how or if it affects PCB warpage and chip component cracking at V-score depanel? Since most FR4 and prepreg has has 1.4 times more fiber bundles in one direct
Electronics Forum | Wed Aug 09 19:14:15 EDT 2006 | Board House
Our Manufacturing policy regarding welds is as follows. 1) Inner layers - depends on Core thickness and line width. Our shop will not do any welding on core thickness less then 5 mils. or line width less then 5 mil. Good AOI practices reduce the a
