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In Solder Rework/Repair, Solder Training and ToolsFREE Inspection mirror

April 2008

 

Dear Subscriber;

In this edition of the BEST newsletter we pleased to tell you about some capabilities that our firm has developed as a response to your needs in the area of testing and reverse logistics.

We have on staff very capable level 3 technicians which can respond to your test and electronics repair. We can diagnose and troubleshoot board problems down to the component level, remove, replace defective components (performing board level repair if required) using our highly-skilled rework staff and handle all of the reverse logistics to get your board shipped back to your end customer. If you need a bonepile sorted through or some boards tested BEST can offload that task from your to-do list.

Do not miss an upcoming learning opportunity which exists on May 8th in southwestern Wisconsin on how to properly handle and deal with moisture sensitive components. With the higher lead free processing temperatures boards and even passive components are now sometimes classified as MSD devices.

We are also pleased to announce that BEST has won the Circuits Assembly's Service Excellence Award -our 2nd year running!!!!


Thanks!

CktBdAnimated

Bob Wettermann
President, BEST Inc

Solder Tips
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BEST Video Soldering Tips

BEST Instructors have put together video demonstrations of common hand soldering tips and skills. These are not designed to be in place of live one on one training where repetitive skills and subsequent one on one feedback is given. Rather, they are quick refreshers designed to be viewed if a specific skill has not been practiced in a while.

 
Electronics Repair and Complete Reverse Logistics

BEST offers the OEM the following "back end" services:

  • In-warranty testing, as well as out of warranty testing
  • Out of Production/Non-Current Electronic Equipment and Component Repair
  • PCB Troubleshooting and component level repair
  • PCB testing and complete assembly testing
  • Electronic data transmission and collection of repair data per your specifications

BEST's Test and Repair Service Depot is your answer for circuit board repair and PCB Testing. We specialize in providing a quality outsource solution for PCB Testing and Board Repair to the industrial, communications, computer and medical industries..


BEST can provide returns processing for warranty administration, returns verification and other programs related to the repairs and the bulk shipments from channel partners seeking restocking.

If inventory management of field spares and management and administration of field exchange programs does not justify a dedicated position within your company than allow BEST to be that management company. This will allow you to implement exchange programs to exceed your customer's high expectations with regards to service levels.

 
 
LEDs 101


Most LEDs have their characteristics specified at a current of 20 mA. If you want really good reliability and you are not certain you don't have worse-than-average heat conductivity in your mounting, heat buildup in wherever you mount them, voltage/current variations, etc. then design for 15 milliamps.

Now for how to make 15 milliamps flow through the LED:

First you need to know the LED voltage drop. It is safe enough to assume 1.7 volts for non-high-brightness red, 1.9 volts for high-brightness, high-efficiency and low-current red, and 2 volts for orange and yellow, and 2.1 volts for green. Assume 3.4 volts for bright white, bright non-yellowish green, and most blue types. Assume 4.6 volts for 430 nM bright blue types such as Everbright and Radio Shack. Design for 12 milliamps for the 3.4 volt types and 10 milliamps for the 430 nM blue.

Next, know your supply voltage. It should be well above the LED voltage for reliable, stable LED operation. Use at least 3 volts for the lower voltage types, 4.5 volts for the 3.4 volt types, and 6 volts for the 430 nM blue.

The next step is to divide the dropped voltage by the LED current to get the value of the dropping resistor. If you divide volts by amps, you get the resistor value in ohms.

For example let's use the following vlaues : 6 volt supply, 3.4 volt LED, 12 milliamps. Subtract the 3.4 volt LED voltage from the 6 volt supply voltage to get a difference (which is across the "dropping resistor") of 2.6 volts. Divide 2.6 by .012. This gives 217 ohms. The nearest standard resistor value is 220 ohms.

One more thing to do is to check the resistor wattage. Multiply the dropped voltage by the LED current to get the wattage being dissipated in the resistor. Example: 2.6 volts times .03 amp (30 milliamps) is .078 watt. For good reliability, I recommend not exceeding 60 percent of the wattage rating of the resistor. A 1/4 watt resistor can easily handle .078 watt.

You can put LEDs in series with only one resistor for the whole series string. Add up the voltages of all the LEDs in the series string. This should not exceed 80 percent of the supply voltage if you want good stability and predictable current consumption. The dropped voltage will then be the supply voltage minus the total voltage of the LEDs in the series string.

 
 
TABLE OF CONTENTS
 
Electronics Test and Repair
LEDs 101
 
QUICK LINKS
 
 
BEST Capabilities Video
EZReball(TM)
Proto Assembly Estimator
 
 
ASK THE EXPERT
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BEST's "Ask the Expert" column is designed to give one-one dialogue between a questioner and our master instructor Kris Roberson. Specification, processing and inspection questions are asked and answered here.

 
PRODUCTS & SERVICES
 
In order to contact customer care on a specific repair project click here
 

BEST INDUSTRY FORUMS
 

This Industry forum is a discussion area where opninons are given on equipment and processes, help is goven on process problems and resources for proble-solving and troubleshooting are shared.

 
WISCONSIN SMTA CHAPTER MEETING
 

The Wisconsin SMTA chapter will be holding a tour and chapter meeting near Madison, WI on Thursday May 8 beginning at 10:30AM. After the tour Steve Martell from Sonoscan will be discussing proper moisture handling of PWBs and passives for lead free process. . More info here.

 

See an interview of BEST Inc-IPC Technology Award Recipient

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SEE Interview of BEST at APEX
 

See the interview of BEST commenting on it being the recipient of an IPC technology award

 

SOLDERING TIPS

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Newsletter

WHAT'S NEW?

VIDEO: BEST at APEX 2017 Convention

ARTICLE: To Bake or Not to Bake (in Rework)

 

 

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