New PIC failure rate

We have been having trouble programming new 16F877, 16F628A & 18F2420 devices using Quasar Micropro 26B2. Currently getting around 10-20% failure rate. Programmer says either ROM error (877 & 2420) or EEPROM error (especially with 628A). Have tried different programmers, different PC & different ICSP lead. Fit new PIC and all is well.

We use surface mount devices and programme with an in circuit facility. We also buy all our devices from reputable suppliers in production packaging. We have even resorted to programming them before loading onto the board to save reworking. Workshop is a fully static safe environment.

Anyone else been having trouble? or can you make some suggestions to stop failures.
Tim.

PS have noticed a supply shortage of some PIC's. Is Microchip having batch problems?

Of the PICs you mention, we use thousands of the 16F628A and the 18F2420... we DON'T do ICSP but always program them before fitting...

We've NO problems with the 16F628A apart from we have discovered that executing an ERASE before programming eliminates 1st time programming errors (even on factory new parts). This is something to we routinely do on all PICs now - not just on this one.

There are unexplained anomalies with the 18F2420... whilst it programs just fine, about 3% have a problem with PORTB.7 on one particular application which tends to go away if you reprogram the PIC a second time. We had a batch in the summer of 2007 which were really flaky and unstable with regard to internal EEPROM which became corrupted very easily. It's a device that comes up with surprises from time to time...

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Originally Posted by Melanie

Of the PICs you mention, we use thousands of the 16F628A and the 18F2420... we DON'T do ICSP but always program them before fitting...

We've NO problems with the 16F628A apart from we have discovered that executing an ERASE before programming eliminates 1st time programming errors (even on factory new parts). This is something to we routinely do on all PICs now - not just on this one.

There are unexplained anomalies with the 18F2420... whilst it programs just fine, about 3% have a problem with PORTB.7 on one particular application which tends to go away if you reprogram the PIC a second time. We had a batch in the summer of 2007 which were really flaky and unstable with regard to internal EEPROM which became corrupted very easily. It's a device that comes up with surprises from time to time...

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Hi Melanie,

What company do you work for

Hi Melanie,
Thats interesting about the erase, had never thought of doing that. Our programmer erases before programming anyway, but I will mention that to the factory chaps and see if it helps.

18F2420 is a recent transition from 16F876 to give us more memory. I pressume the 18F2520 suffers similar problems?

Many thanks
Tim.

High likely a device programmer issue. Might worth to try all their software & driver upgrade
http://www.quasarelectronics.com/micropro.htm

Silicon issue, is also possible... depending where you get them from...

I've got a 60% programming failure rate on 18F4431 devices purchased from Microchip Direct this year.