Trouble selective soldering fine pitch connectors

We are having difficulty with bridging on a 2x50 pin 0.050" fine pitch connector using our selective soldering machine. It usually bridges at the end of the row, but sometimes it bridges all the pins together as it drags across (solid bridging).

I am questioning the viability of soldering fine pitch connectors using the selective soldering process and would like to know from those who use or tried to use selective soldering on fine pitch connectors if you have had difficulty and what level of success you can achieve in terms of first pass yield.

I tried numerous programming strategies such as pulling off at different angles, nozzle height, drag speed, amount of flux, different nozzle sizes, stopping the pump at the end of the row, moving the end point, etc. with no consistent success. We are getting about a 50%-75% first pass yield and management is complaining about the low FPY. Management wants to see 90+% FPY, which is what I'm getting on 0.100" pitch assemblies. I read that having too much or too little nitrogen flow around the nozzle can cause bridging so I now have a flow meter on it but I cannot produce the amount of flow that the support people tell me I should be getting.

Specs: Pillarhouse Jade MKII using Kester 985M flux, 6mm standard nozzle, ultrasonic spray fluxer, pin protrusion = 0.015", 290C Sn63Pb37 pot, liquid nitrogen tank supply.

I would be especially interested in responses from those who have a Jade machine and use SnPb, but all responses are welcome. For those who have a Jade, what is the total nitrogen flow inputted to the machine? I am told that it needs 21CFH for the pump motor and 42-63CFH for the nozzle. I am only getting around 40CFH total with the nozzle supply valve full open, which is only about half the nitrogen I should be seeing at the nozzle. Is this normal in your experience? Thank you in advance.

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