Introduction
No matter how senior an engineer is, the following situations still arise. There are always some inadvertent mistakes, such as reverse connection of positive and negative poles, spacing of a newly purchased terminal blocks being too large, the jack and socket cannot be inserted, or the wrong model is selected so the part size doesn’t match the PCB pads. Many such questions have been sorted out on the TechForum. Let’s sort out five issues that are easily overlooked, so that you can review the past and learn something new.
Part Number Explanation
It is a common industry norm for electronic parts to have different functional options in the same series, so deciding which part number to use is an engineer’s daily task. Sometimes it’s also the biggest headache. A simple part number description can generally be found in the datasheet, but sometimes the differences which may represent different parameter configurations are quite confusing. Unfortunately, not all suffix meanings will list part number details. For example, most of the LED part numbers from OSRAM have a “-Z” suffix, such as LG L29K series. There is no mention of “-Z” in the datasheet. After our verification from the manufacturer, we were able to find out that “-Z” means it complies with lead-free RoHS standards. There are many posts related to part number explanations on TechForum.
For details on this example, please refer to post for details. OSRAM LG L29K series LEDs’ part numbering - “-Z” suffix.
Figure 1 The “-Z” suffix of OSRAM part number indicates compliance with lead-free RoHS standard.
Keep in mind, during the part searching stage, you must determine the proper part number to avoid discovering that the chip configuration is incorrect during the debugging stage, resulting in increased costs and project delays.
Capacitance Value and Soldering of MLCC Capacitor
Many engineers have the experience to measure the capacitance value of their MLCC capacitors, but some of them have overlooked many details, resulting in incorrect test results. As a rule of thumb, you need to read the product specifications carefully. The original manufacturer usually lists the test conditions required for verification of their capacitors. For example, for Samsung’s CL series CL05A104KA5NNNC, the test conditions are 1khz/1Vrms (test frequency 1khz, test level 11Vrms), which is difficult to provide with a multimeter, so high grade measuring equipment such as an LCR tester is required.
In addition, heat treatment and turning on the ALC function of the LCR tester are also key factors. There is a post introduced the three important factors that affect MLCC capacitance measurement, which can be summarized into three “Ts” : Test signal, Temperature and Time. As an engineer, you must be aware of these conditions for proper verification of your capacitors. For details, please refer to the post " Why ceramic capacitors may seem out of spec, but aren’t”
Figure 2 Three important factors for the measurement of ceramic capacitance value : Test signal, Temperature and Time
Let’s talk about soldering for the MLCC capacitors. Some MLCCs are unable to be mounted by reflow methods using flux and solder. That is because this kind of MLCC is not designed for solder mount. For example, TDK’s CGA series capacitors. This is a model containing two different mounting methods in the same series. The first method is reflow solder, while the second can be seen on CGA2B3X7R1H104K050BD. This part number need to use Epoxy Mounting. For further details, please refer to the post “MLCC capacitors with epoxy mounting”.
Figure 3 Specification description of TDK CGA series
Electronics components soldering is definitely not simple, and there are many skills required here. Generally, there are instructions in the product specifications. Some use traditional reflow soldering, and some have special requirements. For example, the MP725 series resistors from Caddock specify that soldering conditions cannot exceed 220ºC. Some original manufacturers use radiators during soldering to protect the product from overheating, such as PUI Audio’s electret condenser microphone products.
In addition to the soldering method, the soldering condition is also very important. For example, temperature often has specific guidelines. Parts also have a moisture sensitivity level (MSL), or humidity control during the storage. For details and an example, please refer to the post " PUI Audio ECM Microphones Soldering Recommendation".
Figure 4 Comparison of C503B-AAN-CY0B0251 to HLMP1700C6A
For power supply products, there are even more testing requirements. Many customers report that the shipped AC/DC converter does not work; they produce no output. In fact, it was because there was no load during the test, such as the XP Power VCS series VCS50US12, load current value is 4.2A required which listed on datasheet, which means that the 12V output operates at a load current of 4.2A. Always ensure to check minimum load requirements during testing of your AC/DC converters.
Figure 5 XP Power VCS series AC DC converter nominal parameters
Fan Labels
A common issue is the current rating on a fan label not matching the datasheet. As an example, the NMB fan 2410SB-04W-B49-B50 is rated at 0.1A in the product datasheet. The fan label shows a different value, 0.14A. If you look carefully at the specification sheet, you will find that the 0.1A on the data sheet is the average value in the atmosphere, and the label is compliance with the requirements under UL certification, so the two values have different meanings. Please refer to another post " Current (Amp) Ratings on Fan Label do not Match Data Sheet" for details.
Figure 6 NMB Fan Label example
Use of Tools
Engineers use a wide variety of tools. Although they use them every day, they might not fully understand the principles of the tools in their hands. Many engineers believe that “Hard Force” can solve everything. They did not realize that this may be the main reason for frequent replacement of tool accessories, or for parts being damaged during assembly with the given tooling. For example, from the model of connector mating terminals, contact crimping tools, or suggestions for using a heat gun, there is a lot of information and requirements an engineer needs to be aware of. There are so many posts sharing these details on TechForum, such as the crimping suggestion and discussion, " How to prepare a hook-up wire before crimping".
Figure 7 Improperly handled wire affects the crimping effect
Please check out the links below for these and other common issues. You’re always welcome to leave a message at the end of an article you are interested in for discussion.
Infineon OPN suffixes (example NTMA1)
Testing High Capacitance MLCC’s
Measuring Low Resistance values below 0.1 OHM
Current (Amp) Ratings on Fan Label do not Match Data Sheet
Safety Operating Heat Guns
How to prepare a hook-up wire before crimping