Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Surface Mount Connector Strength

Wayne

#12937

Surface Mount Connector Strength | 14 January, 1999

I am experiencing a problem with a surface mount coax connector that over time pulls loose from the PWB. The connector has 4 small gold plated leads and we are soldering it to a flash gold board. A cable plugs into the connector and puts some constant torque on the connector. Does anyone know of a good source of information regarding surface mount connector to PWB strength? I would prefer to see a PTH connector in this application but I would like to find some objective evidence that details the strength differences between SM amd PTH connectors.

Thanks.

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Chris G.

#12938

Re: Surface Mount Connector Strength | 14 January, 1999

| I am experiencing a problem with a surface mount coax connector that over time pulls loose from the PWB. The connector has 4 small gold plated leads and we are soldering it to a flash gold board. A cable plugs into the connector and puts some constant torque on the connector. Does anyone know of a good source of information regarding surface mount connector to PWB strength? I would prefer to see a PTH connector in this application but I would like to find some objective evidence that details the strength differences between SM amd PTH connectors. | | Thanks. | Wayne,

I am sure you already know this and have checked for this but make sure that the gold is truely a flash. I assume gold flash over nickel. If gold is between 6 to 10 micro inches then you are probably OK. You may even possibly go higher on gold thickness but you have to watch out for gold imbrittlement problems. Another problem could be your PCB vendor. If the plating is gold over nickel over copper and the PCB sits between the nickel bath and the gold bath, the nickel will passivate causing a poor bond strength of the gold to nickel. I used to work in PCB manufacturing and many thing can happen to cause the gold to not bond properly to the nickel. This is a very common problem. You should be able to identify if this is happening. The gold will break free from the nickel leaving nicle on the pads.

Thanks,

Chris

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Bob Willis

#12939

Re: Surface Mount Connector Strength | 15 January, 1999

| | I am experiencing a problem with a surface mount coax connector that over time pulls loose from the PWB. The connector has 4 small gold plated leads and we are soldering it to a flash gold board. A cable plugs into the connector and puts some constant torque on the connector. Does anyone know of a good source of information regarding surface mount connector to PWB strength? I would prefer to see a PTH connector in this application but I would like to find some objective evidence that details the strength differences between SM amd PTH connectors. | | | | Thanks. | | | Wayne, | | I am sure you already know this and have checked for this but make sure that the gold is truely a flash. I assume gold flash over nickel. If gold is between 6 to 10 micro inches then you are probably OK. You may even possibly go higher on gold thickness but you have to watch out for gold imbrittlement problems. Another problem could be your PCB vendor. If the plating is gold over nickel over copper and the PCB sits between the nickel bath and the gold bath, the nickel will passivate causing a poor bond strength of the gold to nickel. I used to work in PCB manufacturing and many thing can happen to cause the gold to not bond properly to the nickel. This is a very common problem. You should be able to identify if this is happening. The gold will break free from the nickel leaving nicle on the pads. | | Thanks, | | Chris | Just as a reference a 50" lead gull wing will normally give you a pull strength of over 900 g. A 0.025" lead will provide 700-900 g and a 0.020" lead will give you 550-600 g. These are all minimum figures.

A through hole will be in the 20-25 lbs force, lets go PIHR as I am not a lover of connectors over 25mm.

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