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  • Author Author: Former Member
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Problems with MELF resistors?

Former Member
…Most End up Lying on the Floor?!!!!

 

Cylindrical MELF (metal electrode leadless face) resistors can be awkward to mount and require mounting equipment with specialist nozzles to ensure they do not roll away. For this reason the market is moving to SMD resistors in more conventional, rectangular packages. Using SMD resistors reduces costs and increases placement speeds. More, solder joint reliability is improved.

 

Panasonic has a wide range of MELF-replacement SMD resistors:

 

High precision & high stability over the device life time (ERA-Series)

 

0.1%, 25ppm devices are available in 0402, 0603 and 0805 case sizes delivering:                      

 

l High reliability at high temperature & humidity (85°C/85% RH, 1000h; ΔR:±0.1%)
l High resistance to heat: (155degC; 1000h; ΔR:±0.1%)
l AEC-Q200 rated
l High stability over life time
l Moisture resistant technology

 

image

 

For more info, please visit: http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&st=Panasonic%20ERA&pageSize=25&showResults=true&pf=112058930

 

High Pulse Resistance (ERJT and ERJP series)

 

Panasonic ERJP-Resistors have great Anti-Surge characteristics
and excellent heat dissipation characteristics due to
“Serpentine Resistor Pattern Structure” which helps to decrease

 

electric field strength per unit length.

 

Furthermore, squared sized chip structure help to lead to better solder joint reliability which is perfect for a car’s hostile environments.

 

ERJT and ERJP series Anti-Pulse Resistors covering 1Ω – 10MΩ at 0.25W (0805), 0.33W (1206), 0.5W (1210) offer superior pulse characteristics

 

High Power Rating

 

 

 

0603 size ERJP03: 0,20W
0603 size ERJPA3: 0.25W
0805 size ERJP06: 0,5W
1206 size ERJP08: 0,66W
1210 size ERJP14: 0,50W
image

 

 

 

High Power/Current Sensing (ERJB / ERJA /ERJM)

 

Panasonic’s Wide Terminal Resistors are an optimal solution to ensure high power characteristics.
Electronics design engineers have the chance to either downsize their design or save components of conventional technology resistors.
Furthermore high solder-joint reliability through a wide terminal structure yielding a reduction in solder-joint cracks.
Excellent heat dissipation characteristics through wide terminals & separated resistor structure which yields small & high-power characteristic
Current Sense Resistors covering 1mΩ – 100mΩ in 0402 to 2512 packages are rated to AEC-Q200 and feature a large power dissipation capability.

 

image
For more info, please visit:

http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&st=SMD%20Wide%20Terminal%20Resistor%3A%20high%20Power%20%26%20Current%20sensing%20type&pageSize=25&showResults=true&pf=112058931

  • in reply to Former Member

    Now you are doing better -  this is an engineering forum so evidence rather than assertions is always welcome. However your little table is not attributed to any source - for the data to carry any evidential weight you need to explain where it came from. If you take a look at Wikipedia (or any published engineering or scientific papers) you will notice that it is normal to reference the source of information.

    One obvious issue I would take with your  table is that you rate the cost for mounting the 0805 part at 40% of the cost for the 0102 melf but the time taken is (according to your figures)  is 49.75% (of that for 0805). So your table suggests that the cost for mounting the part is not just proportional to the time taken but some higher order function of the time taken - this is a surprising assertion and requires explanation or justification.

     

    I wouldn't (usually) complain about this sort of thing in a personal blog (of which there are many interesting examples on E14) but I expect a much higher standard from blogs posted by large international companies. To my mind, and others may disagree, straight advertising material, like your original posting, has no place in the E14 blogs. Had you posted a technical description of how you measure the pulse handling of your resistors, then that would have been an interesting contribution, and would have much better served your purpose of getting engineers to seriously consider your product.

     

    MK

  • in reply to michaelkellett

    Dear Michael,

     

    Thank you for your feedback.

     

    We regret to hear that you do not like our blog so I would like to take the opportunity to answer your questions.

     

    Our blog is predominantly destined for mass production use. Perhaps you could tell us your application so I can answer your query properly.

     

     

     

    If you use our MELF Replacement Resistor like ERA/ERJ series you will receive better solder joint reliability against temperature cycle. Solder joint strength is much higher in our type of resistors due to its rectangular type. Our resistors are the perfect alternative for MELF because they have high precision and high reliability the whole lifetime through. Also it is proved that they are reliable against humidity. They are better against pulse and have a higher power.

     

    Another advantage is that the productivity will improve because the mounting type of our resistors is 1/3 of MELF.

     

    Additionally the cost advantages play a big point. Please take a look at our comparison


    image


    Best regards,

     

    Natascha

  • This isn't  a blog - it's a sales puff.

     

    It might be more interesting if any actual numerical evidence was offered to support the assertions.

     

    As Don says there is no big deal for hand placing - for machine placement you need statistics and evidence to make a choice.

     

    MK

  • Sometimes it helps to glue them in place with a little liquid flux.  Holding them down with a toothpick while soldering can help.