I'm also thinking of 0402 resistors in regards to this issue:  thinking of concerns of visual inspection (values not usually marked on 0402 resistors, but 5% (E-24) Decades for resistors could be marked on 0603), lead times/availability of parts (suppliers stocking 0402's????), and special nozzle requirements for side 2 placement.  We were unable to use our typical adhesive displacement process for 0603's and smaller and had to resort to stencil paste screening of side two.  I believe different nozzle sizes for pick and place units would also be required.
                                                                    Dean Lillibridge
                                                       NEWvENTURE TECHNOLOGIES 
 
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Pelkey, Glenn
Sent: Wednesday, August 08, 2001 3:56 PM
To: [log in to unmask]
Subject: [TN] Capacitor 0603 vs 0402

Hi all,

        I'm brainstorming on risks and benefits of 0603 caps vs 0402 caps.  If the cap value, voltage rating, dielectric material, terminations, and use conditions are the same, would one be better than the other?  My thoughts are it would be a wash or at least not significant.  Here's what I have so far:

Benefits of 0402 vs 0603:
Smaller size reduces thermal stress/strain on solder joints from CTE or board flexing.
Smaller size uses less real estate on board

Risks of 0402 vs 0603:
Equipment may have difficulty placing
Thinner dielectric spacing to achieve same capacitance, cap higher failure rate
Smaller size, cracks easier to develop
Higher risk of tombstoning

        What do you all think?  I'm sure I missed something, maybe even wrong on some of the above.

Thanks,

Glenn