Don't forget that SMT ceramic caps are now available with flexible
terminations also (for a price!).

Wayne

On Tue, Mar 13, 2018 at 5:25 AM, Yuan-chia Joyce Koo <[log in to unmask]>
wrote:

> be careful wave solder caps - thermal shock sometimes will result hair
> line cracking of cap (ceramic) body... hard to detect by visual and
> open/short test not going to fail either... but performance is not good
> (usually you get field failure after some time...crack propagation to
> critical length that impact performance)... just a reminder..  Better
> method is wave 1st and populate the cap after (your designer should know
> that at preliminary review stage - so you have time to change build
> sequence by design consideration).
> jk
> On Mar 12, 2018, at 11:13 PM, Wayne Thayer wrote:
>
> Hi Carl-
>>
>> That's how SMT started! You don't want the caps on the bottom to be
>> smaller
>> than 0603. Larger is preferred, but those will work. You put the parts
>> down
>> in "SMT Adhesive", which is a high temperature low modulus material. This
>> holds the part in place while it goes through the wave. You want to be
>> careful about any parts going longitudinally through the wave because of
>> the large thermal transient during travel--design the caps so both ends
>> hit
>> the wave at the same time, and you want to go through the wave relatively
>> slowly.
>>
>> But even without that---Why solder 200+ pins instead of wave solder the
>> pins and place the caps manually? For that method you would deposit the
>> paste with a syringe and place the caps in the paste, then send through
>> reflow with the connectors on there. If the connectors can't take the
>> heat,
>> then the caps must be reflowed using hot air rework station.
>>
>> Wayne
>>
>> On Mon, Mar 12, 2018 at 2:22 PM, Carl Van Wormer <
>> [log in to unmask]
>>
>>> wrote:
>>>
>>
>> Our new version PC board has a few bottom-side mounted capacitors that
>>> were not on our previous design.  Both designs are low-quantity builds of
>>> about 100 per year.  Our assembly house says they can’t run the board
>>> through their solder wave because of these parts and is planning to
>>> charge
>>> a significant fee to hand-solder the 200+ pins for the connectors.  I
>>> thought there was some sort of mask that could be placed over the bottom
>>> side parts, like the pink stuff they add to avoid filling the plated
>>> holes
>>> for mounting screws.  Are there any good methods that I should research
>>> to
>>> help them run our boards through the solder wave?
>>>
>>> Also, I tried to find the TechNet archive to search for answers, but I
>>> was
>>> unable to use the search function.  Is there a help file on searching the
>>> TechNet archive?
>>>
>>> Thanks,
>>> Carl
>>>
>>>
>>> ​​​​​
>>>
>>> Carl B. Van Wormer, P.E., AE7GD
>>> Senior Hardware Engineer
>>> Cipher Engineering LLC
>>>     21195 NW Evergreen Pkwy Ste 209
>>>     Hillsboro, OR  97124-7167
>>>     503-617-7447x303
>>>     [log in to unmask]<mailto:[log in to unmask]>
>>> http://cipherengineering.com<http://cipherengineering.com/>
>>>
>>> This message may contain confidential and/or proprietary information, and
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>>> Any
>>> use by others is strictly prohibited.  If I sent this to you by mistake,
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>>>
>>>
>>>
>>>
>