Supplier eBooks

Plugging problems Be on the lookout for metal protruding into open spaces. This manufacturing error will create air-space-distance—a violation of UL requirements for rated voltage. Blisters on housing surface could lead to diminished dielectric voltage withstanding capability. Inconsistent molding Inconsistent molding can lead to several potential problems. Severe cracks will result in loose pins. An unequal opening is too small for mating plug. An angled pin is difficult to place on the PCB. Irregular housing cannot sit flush on the PCB. Inconsistent wall thickness can potentially lead to a broken end wall. With inconsistent key retention features, you will experience a loss of keying capability. Faulty wire cage Connectors manufactured with poor threading can result in bad torque readings, as well as a higher chance for screw back- out. Clearly defined threading creates a secure, longer lasting connection. A diminished cage design is more prone to damage at lower torque levels. Stamping irregularities When a machine wire cage is manufactured with a rough surface, the results are inconsistent performance and diminished mechanical strength. A tiny burr on the contact will cause damage to plating surface. Plating Issues Poor performance The best quality pins are manufactured with nickel under-plating. Pins manufactured without nickel under-plating will be affected by corrosion buildup. This leads to poor solder performance. These two samples from an Energy Dispersive X-ray (EDX) analysis illustrate the effects of not using nickel under-plating. When the base material is exposed due to plating gaps, corrosion buildup can cause increased resistance. Tin whiskers Tin whiskers are hair-like, crystalline structures that can grow on surfaces that use tin as a final finish.1 They are conductive, which can lead to shorts and failures on sensitive electronic equipment. Production practices that mitigate factors that lead to tin whiskers can ensure whisker-free products. Assembly Issues Assembly of plugs There are several signs of careless plug assembly. • A contact gap that is too wide will result in low contact force and high resistance. • An off-center contact placement leads to potential for improper pin insertion. • A closed contact gap can result in potential stubbing or the inability to mate. Assembly of headers and fixed terminal blocks Uneven pins at the mating face will result in potential stubbing and poor connection with high resistance. Uneven pin placement at the solder tails makes it more difficult to place the terminal blocks on the PCB. This will decrease productivity. Quality Terminal Blocks: Materials, Alignment, and Design So now you know how to detect a poor-quality terminal block, but how do you identify good quality, to prevent the problems discussed? Look for manufacturers who use high-quality materials and employ solid assembly practices. PCB terminal blocks typically come in either fixed single-piece design or pluggable two-piece design. Here are some features to look for in each of those styles. Fixed, single-piece design Pin placement – Straight, evenly spaced solder pins allow easy placement on the PCB. Current-carrying bar – Quality materials ensure a low- resistance current path. Look for base materials with high copper content and plating that provide full coverage without voids. MKDSP95 Series Terminal Blocks Learn More 4 • Wave soldering capabilities require less mounting effort and comes in 1 to 5 positions with or without a flanged base • Excellent replacements for costly copper busbars or press-in elements in high-power equipment • Screw connection with tension sleeve for high degree of connection convenience | 7 |

• Cover