tonal
Newbie level 6
Hi everybody,
When using a no-clean reflow soldering process and the residues are still tacky and extend underneath almost any component on the PCB assembly is this considered a potential threat related to ionic contamination, pad, track and terminal oxidation and corrosion, electromigration etc?
In IPC-A-610 there is the following reference (I am talking about class 2):
Defect – Class 2,3
Wet, tacky or excessive flux residues that may spread onto other surfaces.
But right before this reference from IPC-A-610 the following applies:
Acceptable – Class 1,2,3
• Flux residue on, around or bridging between noncommon lands, component
leads and conductors.
• Flux residue does not inhibit visual inspection.
• Flux residue does not inhibit access to test points of the assembly.
And the picture right next to this criterion shows a SOIC with the flux - which to me seems to be tacky - flooding all the area between the IC pins.
In my case the supplied PCBAs have tacky residues that already extend underneath the SMD components nad between terminals.
In this case shall this be considered a defect (according to IPC 1st criterion) or further testing should indicate if the residues could do any harm in the long term?
In general what happens with the no-clean flux during reflow?
It gets more active due to temperature?
And when it cools down and it is not completely consumed (there are still non solid residues) what is its activity level?
Thank you for your time!
When using a no-clean reflow soldering process and the residues are still tacky and extend underneath almost any component on the PCB assembly is this considered a potential threat related to ionic contamination, pad, track and terminal oxidation and corrosion, electromigration etc?
In IPC-A-610 there is the following reference (I am talking about class 2):
Defect – Class 2,3
Wet, tacky or excessive flux residues that may spread onto other surfaces.
But right before this reference from IPC-A-610 the following applies:
Acceptable – Class 1,2,3
• Flux residue on, around or bridging between noncommon lands, component
leads and conductors.
• Flux residue does not inhibit visual inspection.
• Flux residue does not inhibit access to test points of the assembly.
And the picture right next to this criterion shows a SOIC with the flux - which to me seems to be tacky - flooding all the area between the IC pins.
In my case the supplied PCBAs have tacky residues that already extend underneath the SMD components nad between terminals.
In this case shall this be considered a defect (according to IPC 1st criterion) or further testing should indicate if the residues could do any harm in the long term?
In general what happens with the no-clean flux during reflow?
It gets more active due to temperature?
And when it cools down and it is not completely consumed (there are still non solid residues) what is its activity level?
Thank you for your time!