December, 2011


www.us- tech.com High Performance Probe Sockets Continued from previous page


level interconnection. The top side of the elastomer


interfaces with device’s balls and brings the electrical signal down to the test board. The elastomer consists of gold-plated brass wires embedded in silicone rubber. In order to have the lowest resistance electrical path, more than 50 percent of area — pad/ball dimension — must make contact with the top and bottom sides. To ensure proper alignment, all of the compo- nents are precisely positioned with one alignment pin.


Worst Case Scenario In a worst case scenario, the


PCB alignment hole position is +0.025mm; the Ball guide Alignment Hole position +0.025mm; and the PCB Pad location/Size is +0.05mm; the result is a total of 0.1mm off from nominal location alignment.


Marketing of Manufacturing


Equipment Continued from page 65


Growing Offshore Markets When asked if there were any


unmet marketing challenges, the CEO admitted that his company has been engaged in a work-in-progress effort of understanding and address- ing the PCB assembly requirements of growing offshore markets. “Right now, over 30 percent of


our sales are outside the U.S. and Canada. But we still need to improve by making our website easier to understand and by giving ultra-high priorities to installation and after- the-sale service,” he said. Manncorp has sales and demo


facilities in Willow Grove, PA and San Diego, CA, with other offices in Guadalajara, Mexico and Shenzhen, China. The company also maintains a major presence at American Com - petitive Institute (ACI), an equip- ment training and demonstration facility sponsored by the U.S. Navy, where Manncorp machines are avail- able for hands-on demo. ACI is near Phil adelphia’s International Airport. Sales engineers on both the


East and West Coast are reachable by phone, e-mail or text to discuss applications and to answer ques- tions. There are also four full-time techs who install, train and service Manncorp equipment. The market- ing staff includes a director who also oversees public relations and brand- ing, a graphic designer, tech writer, IT technician, a social media and web analytics supervisor and an adminis- trative assistant. They support the rest of the Manncorp team that includes service personnel, sales engineers — plus QA and logistics personnel based in the U.S. and over- seas, who all work in close support with the numerous factories that produce Manncorp equipment. Contact: Manncorp, 2845


Terwood Rd., Willow Grove, PA 19090 % 800-745-6266 or 215-830-1200 fax: 215-830-1206 E-mail: sales@manncorp.com Web: www.manncorp.com r


With 0.24mm minimum pad


diameter for 0.4mm pitch BGA, the elastomer contacts more than 58 per- cent of the pad with 0.1mm off from nominal location. This means that the pin alignment hole and ball alignment hole have to be manufac- tured with very tight tolerance ±0.025mm. This XY variation occurs on each level of the stack up. All the levels should ensure


A BGA socket designed for


1GB Mobile DDR2-S4 SDRAM — 12 x 12mm, 0.5mm pitch, 168 FBGA Package.


greater than 50 percent contact cov- erage area for the best electrical con- nection. Similar calculations have to be made for Z variations and manu- facturing tolerances have to be updated such that >50 percent of pad is covered by elastomer. Alternatively, if spring pins are


Page 67


used instead of embedded wire elas- tomer for interconnect options, the alignment challenge increases 2-fold. First, we have to add spring pin


diameter tolerance. Then, we have to add the tolerance for the hole that positions the spring pin. In order to ensure the proper electrical connec- tion, manufacturing tolerances have to be very tightly controlled for these two additional factors — causing yield issues and high cost. Thus selecting the appropriate intercon- nect medium plays a major role in development cost. Contact: Ironwood Electronics,


Inc., 11351 Rupp Dr., Suite 400, Burnsville, MN 55337 % 800-404-0204 or 952-229-8200 fax: 651-452-8400 E-mail: info@ironwoodelectronics.com Web: www.ironwoodelectronics.com


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