steve, are you making PWA wearable for life insurance company?  ;-) jk
https://www.cbc.ca/news/business/john-hancock-manulife-1.4831629?cmp=rss
On Sep 20, 2018, at 1:03 PM, Steve Gregory wrote:

> Hi Larry,
>
> Did you have these little boards panelized? If so, how did you  
> singulate
> them?
>
> The customer's assembly notes contain a lot of the same Invensense  
> notes
> and also contain statements like: "IT IS SUGGESTED TO USE PLASTIC/ 
> RUBBER
> NOZZLES instead of using metal/ceramic pick and place nozzles.
> - SHARP AND SUDDEN IMPACTS should be AVOIDED.
> - The following Pick and Place parameters are recommended to  
> minimize the
> machine impact force on the MEMS device:
> a. MOUNTER TRANSFER MAX SPEED: 50cm/s
> b. MOUNTER MAX FORCE: 480GF or 4.7N
> C. AS A GOOD PRACTICE, SET UPH (Units Per Hour) OF SMT AS <60% OF IT'S
> DESIGNED SPEED. (example: Panasonic NM-EJMTD designed speed: 35.8k
> Units/Hour)" and: "PCBs that incorporate mounted sensors SHOULD NOT BE
> SEPARATED BY MANUALLY SNAPPING APART. This could also create g- 
> forces in
> excess of 10,000g. (Laser cut should be a good practice). Their  
> notes also
> contain a statement that manual soldering should be avoided.
>
> I can't find out how these InvenSense motion sensors are  
> constructed, but
> it's probably the same sort of construction that the IPhone motion  
> sensor
> is, which is a vibrating fork gyro, here's an IPhone 4 gyro:
>
> https://d3nevzfk7ii3be.cloudfront.net/igi/UurGsklhtJRW2uuB.huge
>
> Obviously there needs to be some pretty specialized processes set- 
> up when
> you are building boards with these motion sensors that I will need to
> account for in my labor quotes.
>
> Steve
>
>
> On Thu, Sep 20, 2018 at 9:37 AM Larry Dzaugis <[log in to unmask]>  
> wrote:
>
>> Assembled similar small boards.
>> Had 11" reeled components. Had to cushion any location where they  
>> were
>> stored on the side.
>> Had difficulty getting the factory to treat then as delicate parts.
>> All assemblies were trayed for handling.
>> It was a no clean process for automotive.
>>
>>
>> On Thu, Sep 20, 2018 at 11:26 AM Stadem, Richard D <
>> [log in to unmask]>
>> wrote:
>>
>>> I worked on the development of MEMS gyro components for Honeywell  
>>> and
>>> Benchmark 15 years ago. They are indeed extremely sensitive  
>>> components,
>>> measuring and controlling pitch, yaw, and thrust on avionics.  
>>> They are
>>> actually a miniature spinning gyroscope on a gantry, and the gantry
>>> measured the interial forces of the spinning gyro. We initially  
>>> had a
>> high
>>> fallout of these components but had great difficulty testing them at
>>> different stages of the process to determine where the shock/ 
>>> vibration
>> was
>>> occurring that caused them to fail. So I assembled a shock/vibration
>> reader
>>> to the output of the MEMS and attached it directly to the CCA,  
>>> which in
>>> turn transmitted a Bluetooth signal to a data receiver/recorder. I
>> tracked
>>> the shock/vibe on a sample of three parts from Honeywell's factory
>> through
>>> the delivery truck through all of the manufacturing processes. It  
>>> was
>> clear
>>> we were looking for a process that delivered steady-state or at  
>>> least
>>> re-curring vibration of such intensity that a sudden drop/upward  
>>> shock or
>>> huge thrust coupled with high inertial forces was causing the  
>>> failures,
>> as
>>> seen by 500x views of the damaged areas. The three samples  
>>> tracked very
>>> similarly throughout their life from fabrication through final
>>> assembly/inspection. I could only track one at a time, but all three
>>> recorded the greatest shock and either partial/intermittent  
>>> failure or
>> full
>>> failure after the in-line wash process. The cavitation of the  
>>> wash water
>>> sprayers caused all three to fail, and were the greatest shock/ 
>>> vibration
>>> readings in their short little lives. So we changed to a different
>> assembly
>>> process, putting the MEMS on after all other processes were  
>>> completed and
>>> used a manual wash process with full blow-off and a short bake  
>>> for 15
>>> minutes at 105 C.
>>> No more failures.
>>> Changes were made to the physical design of the MEMS at that  
>>> time, and
>> for
>>> all I know that could be the component you are dealing with  
>>> today. Or it
>>> may be something entirely different. But I do know this; the wash  
>>> process
>>> can be very destructive on MEMS components for the reasons stated  
>>> above.
>>> Odin
>>>
>>> -----Original Message-----
>>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
>>> Sent: Thursday, September 20, 2018 9:18 AM
>>> To: [log in to unmask]
>>> Subject: [TN] 6-axis MEMS Gyroscope/Accelerometer assembly
>>>
>>> Good morning everyone,
>>>
>>> We're quoting this little 1.5" X 2.5" assembly that has a TDK/ 
>>> InvenSense
>>> 6-axis MEMS Gyroscope/Accelerometer on it (PN# ICM-20648). I've not
>>> assembled a board with one of these devices on it before. When I  
>>> read the
>>> datasheet, and then the handling guidelines for these parts (
>>>
>>>
>> http://www.invensense.com/wp-content/uploads/2015/02/InvenSense- 
>> MEMS-Handling.pdf
>>> ) I was quite surprised how fragile these things are seeing how  
>>> they are
>>> primarily used on wearable devices where they are going to see a  
>>> lot of
>>> shock. Yeah I know it is a MEMS part, but it would seem to me if  
>>> it can
>>> survive all the abuse it will see being in a wearable device that it
>> would
>>> be a little more robust during assembly.
>>>
>>> So have any of you who have placed these sort of devices, have to  
>>> make a
>>> bunch of changes in their standard assembly processes and stockroom
>>> handling practices to accommodate these parts?
>>>
>>> Thanks in advance,
>>>
>>> Steve
>>> --
>>> Steve Gregory
>>> Kimco Design and Manufacturing
>>> Process Engineer
>>> (208) 322-0500 Ext. -3133
>>>
>>> --
>>>
>>>
>>>
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>>
>
>
> -- 
> Steve Gregory
> Kimco Design and Manufacturing
> Process Engineer
> (208) 322-0500 Ext. -3133
>
> -- 
>
>
>
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