James, check data books with the components supplier...the reflow solder
guidelines for SMT of each major supplier are either at back of data book or
in the packaging information.  Altera has special section of handling fine
pitch device.  It has the reflow profile too.
                                     joyce

>>> James 03/18 10:22 AM >>>
Dear Mr.Joyce,
The "reflow soldering guidelines for SMT" is a book ? Or it is company's
manue ?
This informaiton is very useful , thank you !


James Wang

> -----Original Message-----
> From: Leadfree [mailto:[log in to unmask]]On Behalf Of Koo, Joyce
> Sent: Wednesday, March 08, 2000 10:32 PM
> To: [log in to unmask]
> Subject: Re: [LF] ReRe: [LF] SnCu
>
>
> The maximum reflow temperature post by chip manufactures.
> Following are few
> of examles of recommended soldering temperature for Plastic ICs:
> Intel (Microprocessor): Peak reflow temp. 205 to 225 C, @ 120 to 130 sec.
> Component body temp. Max. 220 C.
> National Semi: Peak reflow temp. max. 235 C@ 20 sec.  Recommended
> 220 C @ 5
> sec.
> Altera (FPGA): "Ideally, the leads should only be subjected to the peak
> temperature (220 C) for approx. 10 sec. to reduce the risk of
> damage to the
> solder and devices.  In addition, the device body temperature
> which may vary
> from the temperature of the leads by as much as 15 C----should not exceed
> 220 C."
>
> -All the infor. are from the manufactures' recommended "reflow soldering
> guidelines for SMT".
>
> Hopefully, this clear up the picture a little....
>                                                   joyce
>
> >>> David Gowlett 03/07 1:11 PM >>>
> Dear Dr. Mathias,
>
> The problem now facing the electronics industry is maximum
> temperature that
> electronic components can survive. I accept that changes to the design of
> circuit boards may help to reduce the degree of overheat.
>
> Can members of this forum provide any information as to the maximum
> temperatures that components can survive?
>
> Regards,
> David
>
> -----Original Message-----
> From: Leadfree [mailto:[log in to unmask]]On Behalf Of Dr. Mathias
> Nowottnick
> Sent: 07 March 2000 16:23
> To: [log in to unmask]
> Subject: [LF] ReRe: [LF] SnCu
>
>
> Dear David
> In principle you are right. But sometimes it will be possible to solder
> also below the liquidus temperature. Indeed the amount of solid phase of
> SnCu2 at 235*C will be only in the range of 2% in the melt. You can
> calculate that by the lever rule with the phase diagram for different
> temperatures and compositions. From experience I can confirm, that we
> have soldered successful with a SnCu3 alloy at 240*C. But I like to
> concede, that this must not work for all assemblies.
>
> sincerely
> Mathias Nowottnick
> Group Manager Joining Technology
> Fraunhofer Institute IZM
>
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