Good point! Based on my knowledge, J-STD-020R calls for pre-heat
150-200 C 60-180 sec; above liquidus 217 C, 60-150 sec, peak temp 250
C+0/-5 20-40 sec (possibly for old device format.... Remember the low
voltage IC device got < 0.18 micron... More susceptable to heat damage);
IEC pre-heat 150-180 C/60-120sec, above liquidus 230 C, 25 sec; above
245 C, you risk to damage the parts... The leadfree guys can tell you
more about it .... You may want to find out what is NEC say about your
part.....
jk
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Cyker,
>Howard A (Howie)
>Sent: Friday, April 25, 2003 8:57 AM
>To: [log in to unmask]
>Subject: Re: [TN] SRAM on bottomside
>
>
>Jowan,
>
>Have you confirmed that the TSOP is qualified for the wave
>solder process? The maximum temperature and temperature ramp
>may exceed the manufacturer's
>(NEC) specifications. That may be all the reasoning that you
>need. Otherwise you need to rely on someone's experimental or
>quality data.
>
>Howard A. Cyker
>Lucent Technologies
>Engineering Infrastructure - New Product Engineering
> Email [log in to unmask]
> Phone 978-960-2964
> Fax 978-960-2964
> Pager 888-961-2336
>
>
>
>-----Original Message-----
>From: Jowan Iven [mailto:[log in to unmask]]
>Sent: Friday, April 25, 2003 8:48 AM
>To: [log in to unmask]
>Subject: Re: [TN] SRAM on bottomside
>
>
>Eric,
>
>The fracture is between the component and the adhesive.
>But that problem is already solved.
>We dispense 3 dots adhesive at the two ends of the component.
>Half the dot is underneath the component and the other half
>sticks to the side. It looks strange but it works for us.
>
>I was wondering if anyone has some documents/papers saying
>that TSOP's (SRAM's ,DRAM's etc.) are not really suitable for
>gluing and/or wavesoldering. With such a document it is much
>easier for me to convince the customer to change their design.
>
>
>Regards
>
>
>Jowan Iven
>
>
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Eric Dawson
>Sent: vrijdag 25 april 2003 14:26
>To: [log in to unmask]
>Subject: Re: [TN] SRAM on bottomside
>
>Hi Jowen,
>At the risk of offending the wave soldering fraternity, I have
>two aims in life. The second is to remove wave soldering from
>the production process. My opinion is that reflow soldering
>gives better quality so I promote double sided reflow where I
>can . If this involves pin in hole reflow then so be it. The
>problem is with older designs that have a lot of leaded
>components so I have to accept wave soldering. It may be an
>obvious question, but since the area of these SRAMS is larger
>than the usual SM components, are you printing/dispensing a
>larger area of adhesive? Also, when the components become
>detached, is the fracture surface between the adhesive and the
>board or between the adhesive and the component. The answer to
>this may point you in the direction of the cause of the
>failure. Regards Eric Dawson PS tappity tappity tappity. As
>somebody observed on this forum a year or so ago, this is my
>Friday dance. (With acknowledgements to Snoopy).
>
>> -----Original Message-----
>> From: Jowan Iven [SMTP:[log in to unmask]]
>> Sent: Friday, April 25, 2003 12:26 PM
>> To: [log in to unmask]
>> Subject: [TN] SRAM on bottomside
>>
>> Hi there,
>>
>> One of our customers has put a SRAM (TSOP-54 NEC) on the
>bottomside of
>a
>> board.
>> It is necessary to wavesolder this side so we have to glue this
>> component along with the other smd's The problem is that these
>> components are very susceptible for
>boardhandling
>> and fall off the board to often before the wavesolderprocess. In one
>> way or another the adhesion is not as strong as with "normal"
>> components. In the past we had the same problem with similar shapes
>> from different manufacturers.
>> Luckily we were able to solve those problems.
>> And I think we can solve this one in the same way.
>>
>> What then is your problem, I hear you thinking.
>> It looks to me that these components are not really designed for
>> (glueing,curing and) wavesoldering. And I'm looking for some sort of
>> proof or testresults. Wether I'm right or wrong, I just
>would like to
>> know.
>>
>>
>>
>> Jowan Iven
>>
>>
>>
>>
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