Technical Library | 2021-01-03 19:24:52.0
Reflow soldering is the primary method for interconnecting surface mount technology (SMT) applications. Successful implementation of this process depends on whether a low defect rate can be achieved. In general, defects often can be attributed to causes rooted in all three aspects, including materials, processes, and designs. Troubleshooting of reflow soldering requires identification and elimination of root causes. Where correcting these causes may be beyond the reach of manufacturers, further optimizing the other relevant factors becomes the next best option in order to minimize the defect rate.
Technical Library | 2020-11-09 16:59:53.0
A customer contacted ACI Technologies regarding a high failure rate of their assemblies. They provided assemblies to be X-rayed and inspected for the purpose of identifying any process related issues such as (but not limited to) solder and assembly workmanship and evidence of damage due to moisture related problems during reflow (a.k.a. "popcorning"). Moisture damage usually appears as physical damage to the component. The first indication of moisture damage would be externally observable changes to the package in the form of bulging or fractures to the outer surface of the component, an example of which is shown in Figure 1. Internally observable indicators of moisture damage typically include fractures to the die inside the package and lifted or fractured wire bonds. These conditions would be apparent during transmissive X-ray inspection. Another symptom of moisture related damage would be inconsistent solder joint sizes that result from package deformation during the liquidus phase of the reflow process. None of these indicators of moisture related damage were present on the customer samples.
Technical Library | 1999-05-06 15:14:48.0
To help the designer set the appropriate current level, AMP has developed a new method of specifying current-carrying capacity. This new method takes into account the various application factors that influence current rating.
Technical Library | 2021-08-23 01:53:13.0
After the equipment was introduced, the production capacity was increased by 20%, and the number of operators was reduced by 50%. Employees' salary expenses have been reduced by RMB 120,000 per year, and the pass-through rate has increased by 10% .
Technical Library | 2010-10-21 16:01:17.0
Many component engineers are faced with a circuit requirement calling for resistors having voltage ratings well above that associated with surface mount chip resistors, but below the level of conventional high voltage resistors which are generally availab
Technical Library | 2010-11-06 02:44:38.0
An increasing number of video equipment is running at Gigabit rates today. They are interconnected through relatively large size coaxial BNC connectors. While these connectors are in general of good quality, their performance in the equipment depends on
Technical Library | 2020-07-02 13:29:37.0
Industry standards such as J-STD-005 and JIS Z 3284-1994 call for the use of viscosity measurement(s) as a quality assurance test method for solder paste. Almost all solder paste produced and sold use a viscosity range at a single shear rate as part of the pass-fail criteria for shipment and customer acceptance respectively. As had been reported many times, an estimated 80% of the defects associated with the surface mount technology process involve defects created during the printing process. Viscosity at a single shear rate could predict a fatal flaw in the printability of a solder paste sample. However, false positive single shear rate viscosity readings are not unknown.
Technical Library | 2023-03-13 19:27:13.0
10%) and mean strains (>30%). A trace width effect is found for the fatigue behavior of 1 mm vs 2 mm wide specimens. The input specimen-characteristic curves are trace-width dependent, and the model predicts a decrease in Nf by a factor of up to 2 for the narrower trace width, in agreement with the experimental results. Two different methods are investigated to generate the rate of normalized resistance increase curves: uninterrupted fatigue tests (requiring ∼6–7 cyclic tests), and a single interrupted cyclic test (requiring only one specimen tested at progressively higher strain amplitude values). The results suggest that the initial decrease in normalized resistance rate only occurs for specimens with no prior loading. The minimum-rate curve is therefore recommended for more accurate fatigue estimates.
Technical Library | 2011-03-16 20:05:15.0
Fiber weave effect is becoming more of an issue as bit rates continue to sore upwards to 5GB/s and beyond. Due to the non-homogenous nature of printed circuit board laminates, the fiberglass weave pattern causes signals to propagate at different speeds wi
Technical Library | 2021-07-20 20:12:20.0
Motivation: High reject rates for PCBs due to specification non-conformances Multiple rebuilds causing impactful schedule delays + Copper Wrap + Wicking + Etchback + Annular Ring Are rejected boards reliable? What are PCB quality requirements for? + Reliability: fewer cycles-to-failure? + Manufacturability: define threshold of modern manufacturing capability?
