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Kishan Sarjoo
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Process Engineering Manager - Electronics
Altech UEC, South Africa
Currently with Altech UEC and responsible for technology road map in PCBA electronic manufacturing and technical support for PCBA electronic manufacturing for Altech UEC and its JDM's. Over 7 years in SMT, Radial Insertion, Wave solder & Test Applications.

Kishan Sarjoo has submitted responses to the following questions.
What Caused SMT Pads to Oxidize After Reflow
You should not see this effect, unless you're assembler: Bakes your pcb before manufacturing. Washes your pcb. Process your pcb ...
Requirements for Installing Leaded vs. Lead-free Press Fit Connectors
There is not difference in mechanical strength, when mounted onto the PCB, most press fit connectors are RoSH compliant, meaning ...
Partially Visible or Hidden Solder Connections
Your process team should conduct a study to ensure that the process in reproducible. If you use data that reflects ...
Initial Screen Print Test Board
This depends on the component sizes and paste deposition required. If you are placing any 0.4mm BGA's or 0201 components ...
Stencil Pattern for Thermal Pads on QFNs
IPC 7525, details aperture designs for QFN's. However PCB DFM will allow you to make to calculate this correct volume ...
Soldering Components with Silver Pads
Solder paste manufactures make a low peak temperature solder paste. I have done this before using such solder paste, see ...
BGA Solder Ball Shelf Life
There are no special storage conditions required for solder spheres other than a clean, dry environment(dry meaning that the spheres ...
Calculating PCB Hole Diameters
Aspect ratio is the ratio between the minimum hole diameter and overall thickness of the board. For example; if the ...
Wave Soldering System Nitrogen Use
To calculate this can be quite complex. Typically the manufacture will have this in the machine specification sheet. If you ...
Hot Air Solder 0201s and 01005s
For these type of devices we have switched back to using infrared rework station. It is slow but works amazingly. ...
Stencil Cleaning Frequency
I would recommend reviewing the IPC-7526 document, Stencil and Misprinted Board Cleaning Handbook. It's give you an excellent overview of ...
Customer Approval for Repairs
IPC does not directly dictate the number of times a repair can be conducted on a PCB. However depending on ...
BGA Ball Sheer Testing
What you are seeing is what is expected. However keep in mind. If your objective was to purely test the ...
Cleanliness Standards for Electronic
Try IPC/JEDEC J-STD-033, Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Surface Mount Devices, see image below, of IPC Standards, ...
Overlap Solder Joint Failures
This is a common issue picked up by multiple manufactures which are into L.E.D lighting. The most reliable way to ...
Solder Paste Prep Before Use
Below are the general guidelines to be used for handling solder pastes. The product Technical Bulletin should always be referred ...
Tiny Solder Balls After Reflow
Solder balls can be resulted from a the following processes. Pre-reflow, Washing of PCB's before reflow, if you have had ...
Exposed Copper Risk
Yes you should be concerned if you expect your product to be in the filed longer than 18 months, and ...
How Many Fiducials Pre Solder Paste Stencil?
3 fiducials are the minimum number required, Assuming the 3 fiducials are referred to as A, B and C, fiducials ...