Electronics Forum | Sat Jan 03 18:13:58 EST 1998 | David Jacks
Tom: You are right. Pre-heating is just as necessary in rework as it is in intiial production. Zephyrtronics produces an economical convective bottom side pre-heater known as an airbath. This product ramps the substrate and assembly at 2-4 degrees
Electronics Forum | Wed Jan 30 09:10:48 EST 2002 | bob_smith
Hi Dave, Sorry about that. Specifically, I am referring to radial leads on a crystal. The leads are supposed to be gold plated but only 1/2 to 2/3 of the lead is plated. We bend the lead to form a foot which is soldered to a pad on the PCB. Normally
Electronics Forum | Wed May 29 14:42:53 EDT 2002 | jaltland
I have another question about bga's and stencils. We were told by a manufacturer to use .012 square apertures for .009 dia balls. The original pick & place and reflow goes pretty well (over 95% good), however when we have to select components on th
Electronics Forum | Thu May 30 07:28:15 EDT 2002 | jaltland
Ben, Thanks for the input on the apertures and thickness. The side two problem, is not reflow. We have no trouble with reflow. The problem is that our product is high precision crystal oscillators. In order to get the precision needed, we have t
Electronics Forum | Sat Jun 15 22:39:05 EDT 2002 | edahi
well we can't paste the flip chip on its substrate because we are using flux...because this bare die yet...and the surface of the die flipped might be contaminated...also after chip attach and reflow the die is to be underfilled and if the die is pas
Electronics Forum | Mon Jun 17 21:18:24 EDT 2002 | davef
I don't understand "well we can't paste the flip chip on its substrate because we are using flux". There is flux in paste. What's the difference? If you use solder paste, there will be more room for underfill, as compared to flux only. Some peopl
Electronics Forum | Sat Jun 15 22:49:23 EDT 2002 | edahi
well as usual this for flip chip however, this application uses ceramic substrates and the nearby area in which the splatter land on is the marking area (gold pad). We cannot hide this because the package is completed bare die, meaning no heatspread
Electronics Forum | Wed Mar 05 11:54:44 EST 2003 | ruggi
Hi JFB, I think this is an unnecessary activity, but it may depend on your RH. We are in the Spokane, WA area, and the RH avg year round is about 25-30%. We have never baked our PCBs in the 9 years I've been here across 800+ varieties, including
Electronics Forum | Sat Mar 29 13:35:32 EST 2003 | MA/NY DDave
Hi Back later on this tread, yet I did want to slightly correct one thing DaveyF wrote. Again only slightly. Even at 90C, moisture does start to leave the board. Now it doesn't do it so well as above 100C at sea level atmospheric pressure, yet it s
Electronics Forum | Wed Sep 24 20:04:44 EDT 2003 | Michel Moninger
http://www.mgchemicals.com/products/832.html Loctite makes a version too, if I recall. Designed to be tamper evident, but yes, rework is a bear. We had similar results using one of Lord Chemical's urethane potting compounds. It was a filled black fi
