Electronic Interconnect Offers Direct Thermal Exchange (DTE) Configurations for LED Assemblies

Direct Thermal Exchange (DTE) design in printed circuit boards intended for LED arrays provides a direct thermal path to the base metal of the assembly, allowing the high-power LEDs to dissipate heat effectively, extending their working life and safety in overall functioning.

Electronic Interconnect (EI), a leading provider of printed circuit boards and PCB engineering and design services, now offers Direct Thermal Exchange for LEDs. Thermal Management designs and engineering are an area of specialization and focus for EI.

“DTE enables a very fast rather of thermal transfer through the LTE pad,” Pratish Patel, President, said in making the announcement. “This is an important enabling technology for LED-bearing circuits, especially those intended for outdoor lighting and emergency vehicles where heat dissipation is an ever-increasing concern as the technology of high-power LEDs advances.”
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IPC-1601, Standard on Handling, Packaging and Storage of Printed Boards

IPC-1601 provides users with guidance on how to protect printed circuit board from contamination, physical damage, solderability degradation, electrostatic discharge and moisture uptake. The document covers all phases of production, from the manufacture of the bare printed board, through delivery, receiving, stocking, and soldering. It also gives needed attention to helping users with moisture concerns. The following information provides guidance on establishing recommended moisture levels and baking profiles for moisture removal, and covers the impact of baking on printed board solderability. Moisture absorbed in printed board laminates expands at soldering temperatures, and in some cases the resulting vapor pressure can cause internal delamination or excessive strain on plated-hole walls and other structures. This is especially challenging with the higher temperatures used for lead-free soldering. The costs associated with having too much moisture in a board can be significant. System manufacturers note that if moisture causes problems and ruins boards after parts have been installed, failures can have major repercussions. For information please visit to www.ipc.org.

• The transition to lead-free soldering of printed circuit boards has resulted in a peak reflow and wave soldering temperature increase of 30-40° C for a longer period of time during assembly compared to leaded solder technology.

• These high temperature exposures associated with lead-free soldering assembly conditions result in variations in the circuit board material properties, therefore creating a shift in the expected reliability of the board. This may increase the effect of the moisture that may be absorbed by the base materials; the moisture reduces glass transition temperature of the base material which in turn increases stresses on PCB features and can cause blistering or inner layer delamination.

• IPC standard highly recommends that, baking of the boards prior to assembly is needed to remove the moisture that can be absorbed into PCB; the baking oven is to be set below the maximum operating temperature and glass transition temperature but above 100° C; the baking time should be selected based on the boards features, such as PCB complexity, overall thickness, and PCB finish; it is also recommended that baking be performed in a forced air recirculating oven; it is important to insure proper venting and cleanliness of the oven and sufficient gaps between boards; the boards should never be high stacked inside of the baking oven.

EI’s President and CEO, Pratish Patel, has earned IPC Trainer Certification

Electronic Interconnect’s President and CEO, Pratish Patel, has earned IPC Trainer Certification, and is authorized by IPC to conduct IPC‐A‐600 Application Specialist Training, per the globally‐recognized IPC standard for the acceptability of printed circuit boards. The training and certification program is built on a train‐the‐trainer model. Companies involved in fabrication, assembly, or original equipment manufacturers (OEMs) enroll a representative in a twenty‐hour training course at any IPC Licensed IPC‐A‐600 Certification Center. The training program provides a detailed review of the IPC‐A‐600 criteria and concludes with a qualifying examination. Those who pass the exam are recognized as "IPC‐A‐600 Certified IPC Trainers" and receive instructional materials to use in "Application Specialist" training.
The IPC‐A‐600 Training and Certification Program helps all segments of the electronics interconnection industry improve their understanding of printed board quality issues, greatly enhances communication between PCB manufacturers, their suppliers and their customers and provides a valuable portable credential to industry professionals as well as recognition for their companies. Patel founded EI, a professional printed circuit board designer and manufacturer, in 1985. He has served as Technical Director of the Great Lakes Chapter of the Surface Mount Technology Association (SMTA), directing the chapter’s technical programs. EI serves design engineers and contract assemblers, providing all types of PCBs from single‐sided to complex multilayer boards and Surface Mount (SMT) boards from prototype through production.

Amcon design and contract manufacturer expo

We invite you to visit Electronic Interconnect, booth number 400, at Meydenbauer Center Hall, Bellevue, WA on Tuesday April 12 and Wednesday 13th, 2011.

EI will be representing a Free Seminar on Wednesday, April 13 from 2-3pm in Room 407 for Thermal Management in today's PCB design and fabrication for the LED lighting Markets.

Electronic Interconnect provides Design for Manufacturing (DFM) services

Electronic Interconnect provides Design for Manufacturing (DFM) services automatically for new PCB orders, to detect, identify, and fix design problems before they reach the prototype or production stage. This saves money for customers and prevents manufacturing problems downstream, according to Shehryar Abbasi of EI’s Engineering Department. EI is a PCB fabricator, serving design engineers and contract assemblers, providing all types of PCBs from single‐sided to complex multilayer boards and Surface Mount (SMT) boards from prototype through production.

Before any PCB design goes to even tahe prototyping stage, the engineers at EI subject that design to a number of reviews and checks to make sure that the PCB that the customer requests can actually be built, Abbasi says. Quite often, designers will submit the artwork for a PCB that is superb in concept, but may not be compatible with the limits of the manufacturing process.

“A PCB design may also create issues for the assembly stage, such as a lack of solder mask between component leads that might cause bridging and shorts during the soldering process, when components are attached to the bare board. All of these things must be looked at in light of DFM, Design for Manufacturability and DRC, Design Rule Check principles and limitations. We don’t run files ‘as is’; every board that we make initially goes through a comprehensive DFM check” Abbasi says.DFM at EI includes the following checks:

• Soldermask clearances ‐ distance to keep mask away from solderable areas;
• Soldermask bridges ‐ mask between SMDs to prevent solder bridging during later assembly;
• Trace/Pad Widths & Spacing ‐ minimum spacing and trace widths, trace width tolerances allowed;
• Copper finish ‐ to determine how much artwork compensation needs to be done for chemical processes.

These are the primary checks, but there are many others. For more information and a complete listing, visit www.eiconnect.com.