Prototype TSOP MQFP Solder Mask?

[John H P Southall]

This will be a small company's first attempt at a board with TSOP and MQFP
packages.
We intend to purchase a one-off board from the "PCB-Pool" and we would like
to save costs by dispensing with the solder mask.
We intend to use a "Pace" TempWise with a mini-wave bit; oh and some fume
extraction. Yes and we'll have to get a bit of skill from somewhere too.

Q: Is a solder mask essential, usefull, or just nice on a protype board?.


I have only seen this process done with lots of an unpleasant liquid rosin
flux.
Q: Can you recommend a suitable product?

Q: Would a no-clean water based flux suffice?

Thank you,

John Southall

 

[Boris Mohar]

This will be a small company's first attempt at a board with TSOP and MQFP
packages.
We intend to purchase a one-off board from the "PCB-Pool" and we would like
to save costs by dispensing with the solder mask.
We intend to use a "Pace" TempWise with a mini-wave bit; oh and some fume
extraction. Yes and we'll have to get a bit of skill from somewhere too.

Q: Is a solder mask essential, usefull, or just nice on a protype board?.

I solder these by dragging a fine soldering iron tip over the pins of the
chip that has been tacked down. Stereo microscope is essential for me.

I have only seen this process done with lots of an unpleasant liquid rosin
flux.

Q: Can you recommend a suitable product?

I use a water soluble flux in a felt pen dispenser. It is applied to the
board and again to that pins of the tacked down chip.

If you think that rosin is unpleasant you will not like the water soluble
flux. I use it because it is more aggressive and yo do not need any
chemicals to clean it off.

Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/

void _-void-_ in the obvious place

 

[John Larkin]

This will be a small company's first attempt at a board with TSOP and MQFP
packages.

Good. It's not really hard.

We intend to purchase a one-off board from the "PCB-Pool" and we would like
to save costs by dispensing with the solder mask.

You'll save, what, $5?

We intend to use a "Pace" TempWise with a mini-wave bit; oh and some fume
extraction. Yes and we'll have to get a bit of skill from somewhere too.

Q: Is a solder mask essential, usefull, or just nice on a protype board?.

Useful. Looks nice, too.

I have only seen this process done with lots of an unpleasant liquid rosin
flux.
Q: Can you recommend a suitable product?

RMA liquid rosin flux is not unplesant, aside from being sticky.
Dilute a bit with alcohol, maybe.

Q: Would a no-clean water based flux suffice?

Water-soluble fluxes can leave conductive, hygroscopic ionic residue,
especially under fine-pitch parts that are essentially flat on the
board. That may not matter much if your circuits are all digital.

John

 

[Leon Heller]

This will be a small company's first attempt at a board with TSOP and MQFP
packages.
We intend to purchase a one-off board from the "PCB-Pool" and we would like
to save costs by dispensing with the solder mask.
We intend to use a "Pace" TempWise with a mini-wave bit; oh and some fume
extraction. Yes and we'll have to get a bit of skill from somewhere too.

I use Metcal equipment with a 'hoof bit' for drag soldering fine-pitch
devices. I think Pace makes something similar. I also use a stereo
microscope.

Q: Is a solder mask essential, usefull, or just nice on a protype board?.

I've managed without it on occasions. It does make things easier, and it's
worth paying the extra.

I have only seen this process done with lots of an unpleasant liquid rosin
flux.
Q: Can you recommend a suitable product?

I use an Electrolube SMF12P flux pen. It's not too messy and any residue is
easily removed with IPA.

Leon

 

[John H P Southall]

This will be a small company's first attempt at a board with TSOP and MQFP

packages.

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Thank you for the help,

John Southall