#10314 HIGH Not Tri: XO-1.5 won't boot

[Zarro Boogs per Child]

#10314: XO-1.5 won't boot
---------------------------------------+------------------------------------
           Reporter:  wad              |       Owner:  wad                 
               Type:  defect           |      Status:  assigned            
           Priority:  high             |   Milestone:  Not Triaged         
          Component:  hardware         |     Version:  1.5-C2              
         Resolution:                   |    Keywords:  XO-1.5, boot, solder
        Next_action:  test in release  |    Verified:  0                   
Deployment_affected:                   |   Blockedby:                      
           Blocking:                   |  
---------------------------------------+------------------------------------
Changes (by wad):

  * keywords:  XO-1.5 boot => XO-1.5, boot, solder
  * next_action:  diagnose => test in release


Comment:

 Two boards were given to Via (maker of the CPU) for failure analysis.
 They ground down the motherboard to access traces on the inner layers and
 also the top of the CPU interposer (between the chip and the MB) to access
 the signals, verified that there was no connection and that the I/O input
 on the CPU was undamaged.   They then pulled off the CPUs, and they tested
 fine.

 This indicates that the root cause of this problem is likely to be cold
 soldering (or possibly lead-free solder ball cracking ?)  Quanta will
 attempt to reheat other returned motherboards to see if it repairs the
 problem.  It is likely that the reflow profile for the motherboard
 soldering will be modified to minimize this problem.

 On XO-1, cracking of solder balls underneath the processor has been a
 persistent problem reported by repair centers.  In those cases, it is
 believes that mechanical flexing of the motherboard due to pressure on the
 back of the case was a contributing factor.  In XO-1.5, due to the much
 smaller processor area, we did not expect to see this problem.

-- 
Ticket URL: <http://dev.laptop.org/ticket/10314#comment:15>
One Laptop Per Child <http://laptop.org/>
OLPC bug tracking system