Ask the Experts Member

KN Murli

Head-Quality
Astra Microwave Products, Hyderabad, AP India

Holds Degree in Engineering, started off as Scientist/Engineer in ISRO (Indian Space Research Organization) in Quality Assurance of Space hardware Electronics Production. Worked in the area of Parts, Material and Process; DPA, FA and Process Qualification for space and ground hardware. Later moved into Private sector and worked in the area of Quality Management Systems & ISO 9001 certification. Currently hold a position as Head-Quality in RF/Microwave Product manufacturing for Defense and Aerospace segment.

KN Murli has submitted responses to the following questions.

Customer Approval for Repairs
I do not think there is any IPC requirements that customer boards need customer approval prior to repair.It all depends ...

Gold Plating and Embrittlement
Soldering gold-plated parts can be problematic as gold is soluble in solder. Solder which contains more than 2-3% gold can ...

Manual or Automated Assembly?
Thereare three options in this case:Small bench-top stencil-reflow system is one option.Outsource PCB assembly to regular contract manufacturer for assembly ...

Exposed Copper Risk
The exposed copper is definitely a problem for outdoor environment and humidity.The copper is likely to corrode and eaten away ...

Tacky Substance Under Zero Clearance Parts
One of the methods is how the board is placed the board in Vapour Degreaser. The board has to be ...

ESD Grounding - 1 Meg Ohm Resistor
Simply to protect the personnel from being electrocuted in event any electrical equipment on conductive table top gets short circuited. ...

What Is Acceptable Bending For Assembled PCBs?
It's better practice to avoid any bending on theassembled PCB for two reasons. There has to be some room for ...

Suggested Limit for PCBA Heat Cycles
There cannot be a unconditional defined number of heating cycle that be be permitted for rework on PCB. This has ...

Automatic Insertion Causing Plated Hole Damage
PTH is likely to get damaged if the part lead is stiff and not clinchable easily.Hence it is necessary to ...

Twisting Multi-strand Wires
Multi storied wires should be restored to the original twist and should not be twisted beyond. Tinning takes place through ...

Selective Printing for BGA Components
In my opinion it is fine if some of the non functional points are not soldered. It should be understood ...

What is Causing Solder Joint Cracking?
The failures in solder joints could be due to creep loading. Any mechanical low stress over a long duration leads ...

Cause of Unusual Contamination?
To me it looks like chemical attack of lower layer through the pin holes in the top layer. A close ...

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