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August 21, 2019
Environment Impact on Assembly, Printing and Reflow
At our SMT facility we currently control ambient temperature (20-30 C), relative humidity (40-60%) and particle count (0.5 um not to exceed 100,000 particles, ISO Class 8).

Is particle count a good parameter to control? How can having high particle concentrations affect our PCB assembly process, printing process or reflow process?
J.P.
August 20, 2019
Solder Mask Thickness Tolerance
Our standard PCB fabrication drawing indicates solder mask of 0.8mil thickness. If this is an acceptable standard note, what should be the thickness tolerance plus/minus?
J.L.
August 19, 2019
Calculating PCB Hole Diameters
Our bare boards are typically .065" thick. How can we calculate the hole diameter for connector pins if the board thickness increases to .150"?
P.N.
August 16, 2019
Old Components and Blow Holes
Are old components such as resistors and circuit breakers more likely to cause blow holes during wave soldering compared to new components?
D.B.
August 15, 2019
Trichloroethylene Alternative
We are located in India and manufacture and assemble circuit boards used in watches. We are currently using a mix of Trichloroethylene and IPA for cleaning in the ratio of 10:90.

We are looking to eliminate the use of Trichloroethylene and request your input.
P.N.
August 14, 2019
Production Floor Temperature and Humidity Loggers
Early this month we had a customer audit. One of the findings regards the environment measurements in our assembly area. They noted that we only have one temperature/humidity logger and it was considered inadequate given the size of our production floor.

Isn't one temp/humidity logger per facility adequate? If we add additional temp/humidity loggers, where should we place them? Near machines, near the center of production area, in the four corners?
M.R.
August 13, 2019
BGA Solder Ball Shelf Life
I believe BGA Solder Balls are a homogeneous mass of metals, why is the shelf life only two years? With proper handling and storage, can the shelf life be extended?
V.P.
August 12, 2019
MSD Components Baked Too Long
If MSD components are baked for more time than specified in J Std, can this cause potential failures or other problems? For example, components baked at 125C for 68 hours instead of 48 hours.
V.S.
August 9, 2019
Conformal Coating Press Fit Connectors
We are having problems withpress-fit connectors. We produce military circuit board assemblies andcurrently use a fast drying, single component, acrylic conformal coating.

We previously coated the assemblies theninserted the press-fit connectors. Now some assemblies need to be tested beforeand after coating. Therefore we need to insert the connectors beforecoating process.

Wicking of the coating is a huge problem. If we mask the connectors coating will not be applied to the plated hole pads. IPC-610-E indicates that every connective and soldered point needed to becoated. Is there any exception?
S.C.
August 7, 2019
Depaneling circuit board that contain BGA components
Are there any special requirements for depaneling or V-scoring to separate paneled circuit board if they contain BGA components. What are the best/safest methods for depaneling circuit boards that have BGA components?
A.A.
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