Hi Bill,
The pad size design should be similar to the BGA (per your link). As mentioned by AndyK, the solder paste deposition will determine the height of the solder flow to the pillar (the height and diameter of the pillar also form part of the equation).
Regards
Goek Ang
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Andy Kowalewski
Sent: Friday, 24 March 2017 4:18 AM
To: [log in to unmask]
Subject: Re: [DC] soldermask clearance around BGA balls
Hi Bill,
You're in a swamp at that pitch.Couple of things:
1) Your assembly people need to talk to you. Paste deposition will be a big issue.
2) You won't be able to use a mask because of the 0.1mm (4mil) web thickness needed, unless you
3) Use Mask Defined Pads. These can be copper 0.3mm diameter with a 0.2mm dia opening. That will give you consistent copper area for soldering too.
4) Mask defined pads on a BGA were considered a no-definitely-not strategy, but some studies we did years ago proved that the tendency for balls to crack at the mask edge and spread from there went away if the mask was very thin. We used LPI no greater than 10um thick on the copper and never had a problem. That was on small modules with even finer pitch that 0.4mm
Go for it - the excitement to design where you've not gone before doesn't get any less as we get older. Right?
Cheers........
AndyK
0424 432 235
On 24 March 2017 at 06:58, Brooks, William < [log in to unmask]> wrote:
> I'm playing with some small featured chips and want to create a
> footprint for a .4mm pitch chip with 64 copper pillars rather than solder balls.
> I can't find a recommendation for the land pattern... not one that
> makes sense anyway... :)
>
> How would you approach creating a producible, useful, land pattern for
> this type of chip?
> What clearance would you use for the soldermask around the copper
> pillars and their lands...
> I'm using lead free solder... SAC305.
> Thanks in advance for any advice you may have... :)
>
>
> http://www.topline.tv/drawings/pdf/eWLP/eWLP64T.4-DC088D.pdf
>
>
> William Brooks, CID+
> Printed Circuit Designer
> Nordson Asymtek
> 2747 Loker Avenue West
> Carlsbad, California 92010-6603 USA
> TEL: +1.760.930.7212
> CEL: +1.760.216.0170
> [log in to unmask]
>
>
> This email is intended only for the use of the party to which it is
> addressed and may contain information that is privileged,
> confidential, or protected by law. If you are not the intended
> recipient you are hereby notified that any dissemination, copying or
> distribution of the email or its contents is strictly prohibited. If
> you have received this message in error, please notify us immediately,
> by replying to the message and deleting it from your computer.
> WARNING: Internet communications are not assured to be secure or clear
> of inaccuracies as information could be intercepted, corrupted, lost,
> destroyed, arrive late or incomplete, or contain viruses. Therefore,
> we do not accept responsibility for any errors or omissions that are
> present in this email, or any attachment, that have arisen as a result of e-mail transmission.
>
> ------------------------------------------------------------
> ---------------------
> DesignerCouncil Mail List provided as a free service by IPC using
> LISTSERV 16.0.
> To unsubscribe, send a message to [log in to unmask] with following text
> in the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
> To temporarily stop/(restart) delivery of DesignerCouncil send: SET
> DesignerCouncil NOMAIL/(MAIL) For additional information, or contact
> Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
> ------------------------------------------------------------
> ---------------------
>
---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0.
To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL) For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0.
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------
|
