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Subject:	Re: Voiding on BGA with uVias
From:	Jiang Ping <[log in to unmask]>
Reply To:	TechNet E-Mail Forum.
Date:	Mon, 17 Dec 2001 17:15:46 +0800
Content-Type:	text/plain
Parts/Attachments:	text/plain (1 lines)

You have micro-sectioned, so you could check the roughness and plating quality of  the blind vias' wall. When you find blow holes in THT joints after wave soldering, it's most likely that the fab house has a drilling or plating problem. It may be the reason in your case too. 

Just a clue if you have checked all the possible causes already. If not IPC7095 7.4.1.1 could be a start point. Good luck!



Jiang Ping



----- Original Message ----- 

From: Peter Lee <[log in to unmask]>

To: <[log in to unmask]>

Sent: Wednesday, December 19, 2001 3:20 PM

Subject: [TN] Voiding on BGA with uVias





> Hello,

> 

> We have encountered major BGA voiding issue. The void is sometimes up to

> 70% of the joint. Under X-ray inspection we found a blind 0.006" uVia,

> 0.01" deep under each void. Other BGA solder joint on board w/o uVias do

> not have any void problems. Board is gold over Nickel finish and 2mm

> thick.

> 

> Things we tried:

> Reflow profile - WS/ no-clean paste, longer soak

> Washing/ baking the bare PCB

> Reworked by cleaning the uVias/pads and filled with solder but still

> seeing void

> 

> Has anyone seen this before? Micro-sectioning clearly showed the void

> originated from the uVia. We are trying to convince the board house that

> it's not our process.

> 

> 

> Rgds,

> Peter

> 

> 

> 

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