March 2010 Vol. 2, Iss. 29
In this newsletter we discuss the head-in-pillow defect which BEST has been seeing more and more often as it works with clients on solving process problems and repairing BGAs. In addition, we look at the pluses and minuses of the Bloom fuel cell that has been in the news lately.
We also invite you to our next teaching tutorial:
We invite you to PRE-ORDER YOUR IPCA610 REV E version prior to its expected release in April.
See you at APEX!
President, BEST Inc
|Head in Pillow |
We have been seeing more and more of the head-in-pillow (HIP) defect. The two main issues which cause this defect are:
Random head-in-pillow defects are from poor wetting and edge or center defects are from warpage. Supply issues such as oxidation, or any other oxidation/hydroxide effects lead to these type of defects. Process issues such as printing, placement and reflow can be causal effects related to this defect type.. Material issues such as the soldering itself, wetting capacity or flux exhaustion are other potential factors leading to head-in=pillow defects.
Printing, placement and reflow issues can lead to head-in-pillow defects. Printing issues such as poor registration, imperfect or improper printer setup and poor stencil design can lead to HIP defects. Poor registration leads to printing off-pad or pump-out, and is only part of the printer setup. Printing too fast or too slow will alter the amount of solder that is printed, as well "scooping" paste out of the apertures. Stencil design is probably the most important of the process issues. A bad stencil design can lead to insufficient solder deposits, which can cause the component to not even touch the paste as well as not having enough flux to overcome the oxide on the sphere or in the paste. Area ratio plays a large role, as well as transfer efficiency. Placement is another problem area as offset can be a causal factor to head-in-pillow.
The majority of the head-in-pillow defects come from the reflow process. This is where warping of the component actually lifts one edge, opposite edges ("potato chipping") or even the corners or center spheres. This is why it is important to read the component manufacturer's recommendations, so the reflow temperature doesn't exceed the maximum processing limitations. Another issue in reflow is flux exhaustion, where the flux loses activation because the reflow profile is too long. Care must be taken when processing in order to eliminate this problem.
BEST can help you diagnose (through cross-sectioning, warpage measuring and other testing) and repair these defects in many cases. Call Laura Ripoli at (847) 797-9250 to see if we can help.
| What's with the Bloom Box Fuel Cell? |
The Bloom Box is the creation of Bloom Energy, a Sunnyvale, California-based company that is promising to revolutionize energy with its "power plant in a box.This company claims that it will be able to make fuel cells inexpensively enough for them to be deployed to residential and commercial customers. Instead of having centralized power plants, you would have distributed micropower.
The fuel cell stacks are housed in a refrigerator-sized unit - the Bloom Box. Oxygen is drawn into one side of the unit, and fuel (fossil-fuel, bio-fuel, or even solar power can be used) is fed into the other side. The two combine within the cell and produce a chemical reaction that creates energy with no burning, no combustion, and no power lines.The green credentials depend on the fuel source.If they use natural gas as a source of hydrogen, CO2 will still be emitted.
The idea of fuels cells have been around for several hundred years. The downside to this technology remains the lack of efficiency and the need to produce/harvest the input (gas, biogas) to the process.
This recently-hyped product produces electricity from nearly any fuel source and can also store it like a battery.The company says that its cells are inherently cheaper and more scalable than anything we've seen to-date due to their reliance on low cost and abundant materials. However, this is marketing hype until they get prices way down (their pilot boxes, sold to the likes of eBay and Google, come in at $700,000 to $800,000, which is 20 times the fuel cell price targets set by U.S. research labs to achieve widespread adoption). As it is, most analysts predict that electricity from Bloom boxes will require subsidies to meet and beat the rates provided by the grid.
Two more intriguing ideas have floated out of the Bloom buzz. The first is the notion that Bloom might not sell boxes, but rather the electricity they produce. In this case, customers would not have to take on the risk of the upfront capital investment, which could enable a more rapid ramp up and faster achievement of economies of scale.
|TABLE OF CONTENTS|
|Head In Pillow|
|BEST Obtains ISO 9001:2008 Registration|
|BUY your Advanced Copy of the NEW IPC-A610-E |
Order an advanced copy of the IPCA-610E including updated criteria with respect to wire and terminals, bottom-terminated devices and more. Revised standard expected out in April.
|Order a FREE Reballing Preform Eval Kit|
If you want to simplify the rework of your leadless devices then try out the BEST EZReball(TM) here.
|VOCAB- Word of the Month |
steenth"steenth" which is an adjective;
The vocabulary you use tells others your level of intellect.
Definitions: Latest in an indefinitely long sequence.
or one sixteenth.
Usage: "And for the steenth time I wondered why he hadn't phoned me."
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