Need easy way to pass thru lines on TSSOP pad on board

Questions relating to designing PCBs

Moderator: phalanx

Post Reply
eagleski
Posts: 2
Joined: Tue Sep 26, 2017 4:41 pm

Need easy way to pass thru lines on TSSOP pad on board

Post by eagleski » Tue Sep 26, 2017 4:43 pm

Folks,
I'm trying to find an easy way to lift a TSSOP part off of a production board and replace it with a part that would have a straight pass thru on 5 of the data lines. Unfortunately we don't want to use this TSSOP voltage leveler and need it to just pass thru 3.3V signals directly.

Is anyone aware of a straight pass thru for TSSOP parts that would simplify the rework? Yes, we should have caught this in design, but with 60 boards out there, we can't just start over.
Thanks,
Eric

User avatar
phalanx
Non-SFE Guru
Posts: 1949
Joined: Sun Nov 30, 2003 8:57 am
Location: Candia, NH

Re: Need easy way to pass thru lines on TSSOP pad on board

Post by phalanx » Wed Sep 27, 2017 5:56 am

You can remove TSSOPs in a few ways. The easiest is to use a hot air rework station. You heat the whole part and once the solder melts, just lift it off. If you don't have access to a rework station, with a hobby knife or other fine tipped cutting device you can cut the pins where they enter the TSSOP package on both sides, lift the body of the part out, and then individually remove the pins from the board using a soldering iron.

You're unlikely to find a drop in part that only passes through the specific pins you need. You will most likely have to solder tiny jumper wires in place between the correct pads for the removed part. This isn't uncommon in the world of PCB development.

Hope that helps.

-Bill

n1ist
Support Volunteer
Posts: 990
Joined: Wed Mar 22, 2006 11:02 am

Re: Need easy way to pass thru lines on TSSOP pad on board

Post by n1ist » Wed Sep 27, 2017 10:00 am

If you are OK with 10 ohms resistance, there are some TSSOP isolated resistor arrays. You didn't mention the pinout or part size so it is difficult to give any better info.
/mike

eagleski
Posts: 2
Joined: Tue Sep 26, 2017 4:41 pm

Re: Need easy way to pass thru lines on TSSOP pad on board

Post by eagleski » Wed Sep 27, 2017 2:09 pm

Thanks for replies...I attached that part of the circuit.

The part is a TXB0108PW which has 20 pins. It translates SPI and 2 signal lines. It really only works when going from 3.3V to 5V, but we need 3.3v.
It took a long time to rework this with individual wires, so probably not a good option for 50 boards...

I do not know if a 10 Ohm would be an issue for SPI interfacing, but would think not...

How to track down TSSOP resistor arrays? Who makes these?

Thanks,
Eric
Attachments
TXB0108PW snap.jpg

n1ist
Support Volunteer
Posts: 990
Joined: Wed Mar 22, 2006 11:02 am

Re: Need easy way to pass thru lines on TSSOP pad on board

Post by n1ist » Fri Sep 29, 2017 4:49 am

I just went on Digikey and did a search. Vishay VSSR1603100GUF looks like what you want. You can check Mouser as well or just search with Google.
/mike

Post Reply