Yes this is all true but you may need to reduce the number of holes in a
mouse bit design for lead free. Also you may see issues with break out on
high tg laminate. The break out section will be rougher. On some materials
much of the resin separates from the glass.

Breakout of boards and the design is never mundane you ask the guys on the
shop floor that at doing it?

Have to say I am "Gobsmacked" by my first trip to Las Vegas, its like
Blackpool/South end in the UK on steroids. 

Bob Willis
2 Fourth Ave, Chelmsford, Essex, CM1 4HA England
Tel: (44) 1245 351502
Fax: (44) 1245 496123
Mobile: 07860 775858
 
www.ASKbobwillis.com
 
Book your place on Bob's "Step by Step Failure Analysis Workshop" 14th May
www.ASKbobwillis.com/faworkshops.pdf
 
 New "Printed Board Inspection & Quality Control" 3 July
www.ASKbobwillis.com/PCBworkshop.pdf 
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee parker
Sent: 27 March 2008 17:26
To: [log in to unmask]
Subject: Re: [TN] Breakaway tabs

Eddie

While this may appear to be a very mundane issue it is complicated. For 
instance are you using a fixture to hold the board and minimize stress 
concentrations. As you suggest, drilling holes along the cut line will help.

Also scoring the tabs along the fracture line will also minimize 
delamination. It has been my experience that the breakaway tabs must be 
designed to be compatible with the paneling strategy and the board removal 
process.

Best regards

Lee

J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389


----- Original Message ----- 
From: "Eddie Rocha" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, March 27, 2008 12:36 PM
Subject: [TN] Breakaway tabs


> Is there a standard for designing breakaway tabs? Or a standard on how 
> much
> mechanical stress during the breaking of tabs should a PCB withstand?
>
> I have a customer that is using tabs .125 wide with no breakaway holes. 
> They
> experience slight delamination/fracturing after they break these tabs.
>
> thanks,
> Eddie
>
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