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www.us-
tech.com IPC-CFX Process Control and
Traceability: Real-Time Risk Mitigation in Hand Soldering
By Hoa Nguyen, CTO, OK International, and Ed Zamborsky, Regional Sales Manager, Metcal H
and soldering is the process of joining two metals using a filler material, known as sol- der. The solder is typically a metal alloy
with a lower melting point than the metals being joined. This is sometimes confused with weld- ing, but the main difference between soldering and welding is that in soldering the joined met- als are not melted. This process has been in use for millennia,
as experts agree that hand soldering was employed as early as 5,000 years ago in Egypt. The use of soldering as an assembly process grew in popularity around 4,000 years ago when tin was discovered as a flowable metal joining material. This technique for soldering quickly
expanded from the Mediterranean region and was introduced to the Roman Empire, Swiss and Hungary. The soldering process has improved from culture to culture and from gen- eration to generation. Yet, for all this experi- ence, today’s electronic assembly still suffers from manufacturing issues caused by this age- old process for joining metals.
production line running and our investors happy. One of our largest overhead items is the cost to provide industry-standard training to assembly operators who practice the art of soldering daily.
despite training, practice and inspection, we can deliver products with latent defects. As an example, in December 2015, Ford
Motor company issued a recall for 313,000 older cars for headlight failures linked to 11 crashes. The automaker recalled 2003 to 2005 Ford Crown Victorias and Mercury Grand Marquis to replace the lighting control module. The modules’ solder joints could crack and inter- rupt power to the headlights, increasing the risk of a crash at night. The reliability of solder interconnections
Intermetallic compound layer (IMC) of a solder joint.
Standards for Safety The electronics industry has implemented
many standards over the years to ensure that the products we build meet our customers’ needs for safe and reliable operation. As manufacturers, we must allow for profits to be achieved to keep our
Typically, these standards are based on the visual appearance of the final soldering joint. Many operators will only gain this expertise
after years of experience and many training ses- sions. That being said, hand soldering is still an art and dependent upon human behavior. Unfortunately, as humans we are fallible and
depends on intermetallic compound (IMC) for- mation which is a function of time and temper- ature. The reflow peak temperature and the time above liquidus are two critical variables in determining the IMC thickness. The IMC is necessary for good solder joint interconnection and its presence provides a bonding layer between the solder and component termina- tion and/or board substrates. Solder joint reli- ability can be affected by both the lack of an IMC layer and too thick an IMC layer. If a thick IMC layer was formed within the solder
joint, its brittleness can cause solder joint reliabil- ity concerns.
Connection Validation The Connection Validation (CV) soldering sys-
tem was designed by Metcal to allow for the repeat- Continued on next page
An Excellent Duet!
May, 2019
Coupled Inductors The WE-MCRI is an innovative molded coupled inductor with fully automated bifi lar winding process. It offers an almost ideal coupling coeffi cient up to 0.995. The WE-MCRI features a soft saturation behavior with its crystalline core structure and distributed air gap. The coupled inductor range includes high voltage isolation versions up to 2 kV, low profi le types and versions with various turns ratios.
For further information, please visit:
www.we-online.com/coupled
Up to 0.995 coupling coefficient Up to 2.0 kV isolation Soft saturation Up to 120 A ISAT
and 48 A IR Large portfolio #INDUCTORDUET PCIM Europe Hall 7 Booth 229
See at EWPTE, Booth 1623 and PCIM, Hall 7 Booth 220
© eiSos
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