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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Richard Jackson

#15180

Gold boards | 1 July, 1998

I'm having a problem getting good reflow on gold sufaced boards. The profile looks good and I have adjusted it both hotter and colder and adjusted the various times ( soak, reflow ) to no avail. What realy gets me Is that a month ago we built some gold surfaced boards with no problems ( actualy they ran great ) Now I get these and I have problems reflowing them. Their is a differance in apperance between the ones that ran well and those that don't work at all. The ones that ran well were dull where as the ones that don't want to work look polished. Also when you look at the joint under a scope it looks reflowed but it doen't completly wet to eather the pads or the componet. It also has what appers to be some kind of contamination on the outside of the joint. Thanks Richard

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Earl Moon

#15183

Re: Gold boards | 1 July, 1998

| I'm having a problem getting good reflow on gold sufaced boards. The profile looks good and I have adjusted it both hotter and colder and adjusted the various times ( soak, reflow ) to no avail. What realy gets me Is that a month ago we built some gold surfaced boards with no problems ( actualy they ran great ) Now I get these and I have problems reflowing them. Their is a differance in apperance between the ones that ran well and those that don't work at all. The ones that ran well were dull where as the ones that don't want to work look polished. Also when you look at the joint under a scope it looks reflowed but it doen't completly wet to eather the pads or the componet. It also has what appers to be some kind of contamination on the outside of the joint. | Thanks | Richard

Richard, As an extreme advocate to replace HASL and OSP's (just because it's time to achieve solderability and flatness), I'm always very dissapointed to hear such descriptions. May I ask the specifications for gold over nickel (thickness, electroless or not, etc.). Also, may I ask if the same supplier did both board types (those solder wetting and those not). Also, I am very disturbed by a recent announcement concerning electroless nickel and the reliability issues concerning it under electroless gold. We must continue discussions to ensure initially acceptable quality and long term reliability. Someone has some answers we're not getting until it's too late. Let's all get the facts from those who know but are not telling because they are protecting their asses. We need to know. Earl Moon

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Steve Schrader

#15182

Re: Gold boards | 2 July, 1998

| I'm having a problem getting good reflow on gold sufaced boards. The profile looks good and I have adjusted it both hotter and colder and adjusted the various times ( soak, reflow ) to no avail. What realy gets me Is that a month ago we built some gold surfaced boards with no problems ( actualy they ran great ) Now I get these and I have problems reflowing them. Their is a differance in apperance between the ones that ran well and those that don't work at all. The ones that ran well were dull where as the ones that don't want to work look polished. Also when you look at the joint under a scope it looks reflowed but it doen't completly wet to eather the pads or the componet. It also has what appers to be some kind of contamination on the outside of the joint. | Thanks | Richard It sounds to me like your board vendor used a gold plate (~30 microns of gold) instead of Immersion Gold (3-5 microns). Send a sample back to the vendor or an outside lab to measure the thickness of gold. I've had this happen to me. The shiny finish is a pretty clear indication that this is what happened.

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Justin Medernach

#15184

Re: Gold boards | 2 July, 1998

| | I'm having a problem getting good reflow on gold sufaced boards. The profile looks good and I have adjusted it both hotter and colder and adjusted the various times ( soak, reflow ) to no avail. What realy gets me Is that a month ago we built some gold surfaced boards with no problems ( actualy they ran great ) Now I get these and I have problems reflowing them. Their is a differance in apperance between the ones that ran well and those that don't work at all. The ones that ran well were dull where as the ones that don't want to work look polished. Also when you look at the joint under a scope it looks reflowed but it doen't completly wet to eather the pads or the componet. It also has what appers to be some kind of contamination on the outside of the joint. | | Thanks | | Richard | | Richard, | As an extreme advocate to replace HASL and OSP's (just because it's time to achieve solderability and flatness), I'm always very dissapointed to hear such descriptions. May I ask the specifications for gold over nickel (thickness, electroless or not, etc.). Also, may I ask if the same supplier did both board types (those solder wetting and those not). | Also, I am very disturbed by a recent announcement concerning electroless nickel and the reliability issues concerning it under electroless gold. We must continue discussions to ensure initially acceptable quality and long term reliability. Someone has some answers we're not getting until it's too late. | Let's all get the facts from those who know but are not telling because they are protecting their asses. We need to know. | Earl Moon Guys, Don't jump to unnecessary conclusions. The gold's too thick, nuff said. I'd bet my gut. (That way if I lose, I still win!!) Nuff of the yuk yuks too. The plate is too thick on this board. Betcha used a mom and pop fab shop. "Ayup, we got an immersion gold line. Is it a difficult process? Naww." Qualify your vendors first! Take a good pole of their customer base. Don't just find out capabilities (do they have the equipment). Find out if they are capable of using it effectively. Vendors can be looked at from a Cp / CpK standpoint too. Just because someone has the capability to do something (Cp) doesn't mean that they can do it well (CpK). Immersion gold is a very good process and can be absolutely fabulous to work with, from a component population standpoint, when the fabs are done properly. When they get messed up, as in Richard's case, the process simply doesn't work. Not only does it not work but those cards and everything on them are, for all intensive purposes, scrap. Richard, don't whack the process. Whack the processor. Any kind of plating thickness analysis is going to tell you that the gold is probably 9x thicker than what it should be. Regards, Justin Medernach

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Bruce Houghton

#15181

Re: Gold boards | 6 July, 1998

| I'm having a problem getting good reflow on gold sufaced boards. The profile looks good and I have adjusted it both hotter and colder and adjusted the various times ( soak, reflow ) to no avail. What realy gets me Is that a month ago we built some gold surfaced boards with no problems ( actualy they ran great ) Now I get these and I have problems reflowing them. Their is a differance in apperance between the ones that ran well and those that don't work at all. The ones that ran well were dull where as the ones that don't want to work look polished. Also when you look at the joint under a scope it looks reflowed but it doen't completly wet to eather the pads or the componet. It also has what appers to be some kind of contamination on the outside of the joint. | Thanks | Richard Did the board fabricator apply the Ni/Au before of after solder mask? If the Ni/Au was applied before solder mask, and you are seeing a shiny gold surface, you may have some solder mask residue left on the gold. It looks nice and shiny but the solder won't wet to the pads.

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