Electronics Forum | Fri May 10 01:41:04 EDT 2002 | ianchan
Steve, Hi mate, was doing some text book reading and saw this one paragraph that commented on the PCB fab plating could have residue chemistry inherent in the PCB if the fab process control isn't up to mark. such chemistry could surface to the Au/N
Electronics Forum | Thu Jun 13 06:08:57 EDT 2002 | edahi
guys thanks for the suggestions... DaveF, *Changing paste EricD: Yes we are considering that as a point. Because I believe the paste we are using are in syringe packaged and designed for dispensing. We are using an Indium SMQ75 paste and current
Electronics Forum | Wed Jun 26 01:01:24 EDT 2002 | ianchan
Steve, Dason has valid points here. dun listen to what supplier's say about paste lying on the PCB pads able to be exposed at ambient temperatures for 8-24 hrs? that will never get approval for Class-3 type of customer auditors. (Would any serious
Electronics Forum | Wed Aug 14 16:44:54 EDT 2002 | dragonslayr
What is the surface finish? HASL, Entek? what? If HASL, ask your fab supplier for recommendations, maybe even rerun the boards through the HASL process. The fab house would have to strip off the old coating and reapply. Just a thought, depends on y
Electronics Forum | Wed Sep 18 10:06:30 EDT 2002 | Bob M
I place 15-20 mil a lot. You need to look at your pad to apature reduction. Your stencil thickness. The type of paste your using. We use 2-5 mil reduction on each side as a general rule on fine pitch. This varies depending on pad width. We also use 5
Electronics Forum | Thu Nov 14 11:08:29 EST 2002 | bcceng
Kevin, I have done the following process to a similar problem: 1. Plug holes (even to both sides of the board) 2. Clean any flux left on the surface, especially on bottom side. 3. Apply Kapton tape to the bottom side, you mite want to apply 3 layers
Electronics Forum | Mon Dec 02 09:47:54 EST 2002 | davef
Most modern spec do not distinguish between process methods. So, there is no allowance "if you are using bla bla bla method, you should see ... . But if you are using bla bla de bla method, ignore that and look for ... ." Most specifications requi
Electronics Forum | Mon Jan 13 16:24:15 EST 2003 | russ
Youch! I know this is going to sound stupid but.... I have done it in the past in limited quantities. We placed capton (polyimide) tape at each of the four corners for a similar situation. It did work but the operator has to be careful in placing
Electronics Forum | Mon Jan 20 17:42:45 EST 2003 | jonfox
Double check the data sheets for your paste. Just as an example, ou Indium paste has a recommendation for the Heating, Liquidus, and Cooling stagees of reflow. They recommend a linear ramp up of 0.5 to 1.0 degree C. In the Liquidus stage, a peak t
Electronics Forum | Thu Feb 27 12:23:47 EST 2003 | woodsmt
James, Have you considered going to a No-clean process? BGA's can be difficult to impossible to clean using an aqueous process. The water just won't penetrate under the entire BGA and efficiantly remove your flux residues. The tighter the pitch
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