OTP versus soldering process
OTP versus soldering process
(OP)
Hi,
I have the option to use OTP microcontrollers (an old 87C42) on a surface-mounted board. I am wondering if the OTP can lose its contents when it is subected to the heat of the surface mount reflow. Or should I use sockets all the time? Did anyone go through an issue like this?
Felixc
I have the option to use OTP microcontrollers (an old 87C42) on a surface-mounted board. I am wondering if the OTP can lose its contents when it is subected to the heat of the surface mount reflow. Or should I use sockets all the time? Did anyone go through an issue like this?
Felixc





RE: OTP versus soldering process
Dan
Owner
http://www.Hi-TecDesigns.com
RE: OTP versus soldering process
RE: OTP versus soldering process
leonar40, this is for a "shrink down" design, that allows no software rewriting, so I am stuck with this MCU. Take a look at the Zilog Z8Encore chips, they're cheaper than the equivalent PICs.
RE: OTP versus soldering process
The EPROM variety was basically a UV-erasable EPROM without a window, hence OTP. Slightly less robust, but a short jaunt through a reflow machine should be no big deal, since they were capable of maintaining storage at 125ÂșC junction temperatures for years.
TTFN
RE: OTP versus soldering process
<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032
RE: OTP versus soldering process
I'll try to manage enough space for PLCC SMT sockets so both ways will do.
RE: OTP versus soldering process
Flash devices are only now starting to be cheaper for 8 bit processors, i can still get fairly powerful 8bit OTP processors from motorola that do the job and are dirt cheap...
I actually just started a design with a 16K ROM, 1.1K ram, full LCD driver, DTMF encoder/decoder, 4 8 bit i/o ports, PLL, timers, interputs etc for US$1.60... Like to see somthing like that in flash :) not likely :) but would LOVE to be proven wrong!! (i only really need the DTMF enconder/decoder, but this is cheaper than mode DTMF encoder/decoders that i could find with a cheap micro)