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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


HASL Plating Thickness

C Lampron

#29682

HASL Plating Thickness | 27 July, 2004

Good Morning Everyone,

Could someone please tell me what the acceptable range is for HASL plating thickness. We have some raw boards with plating thicknesses ranging from 3-4 mils on a fine pitch QFP. We are expeiencing bridging at this location and am just trying to educate myself prior to conversations with the board house. Any help would be greatly appreciated.

Thanks

Chris

reply »

#29686

HASL Plating Thickness | 27 July, 2004

HASL Thickness: * HADCO DFM manual specifies a nominal thickness of 50-1500uin with an option for 100-1000uin * Merix DFM manual specifies 30-200uin * Our boards (from a major fab) average 500uin with an "as measured" range of 300-800uin

Be careful in approaching this strickly from a "thickness" point of view. To us, the issue became consistancy of thickness. From the following stand points: * Across the pad * From lot to lot

Others with your bridging issue have opted for a flatter surface [eg, OSP, imm Ag. imm Sb, ENIG, etc] with fine pitch parts.

reply »

Nippy

#29687

HASL Plating Thickness | 27 July, 2004

How does the HASL finish and stencil match ? I have seen ocasions on fine pitch devices where the HASL can protrude into the stencil aperture either pulling paste down on the snap off or completely blocking the aperture and getting no paste.

reply »

C Lampron

#29698

HASL Plating Thickness | 27 July, 2004

Nippy,

This is exactly what we are seeing. The exessive pads are all on one side of the board. This is a 10 up panel 5x2. All of the QFP's on one side on the panel are not releasing or are not gasketing and causing bridging. So the defects are ranging from insuficiant to bridging. This one has kept me busy. I think I have an answer. The plating on this board is ranging up to 2 Mils and is extremely inconsistant.

Thanks For The Help

Chris

reply »

Nippy

#29733

HASL Plating Thickness | 29 July, 2004

Go for a silver finnish if you can...

reply »

SMT in-printer dispensing

Reflow Ovens thermal process improvement