2
Service and Maintenance
40
Keysight U1818A/B Operating and Service Manual
A close-up of the ZIF probe head inserted into the ZIF tip is shown in
Figure 2-31
.
Note that now the lever on the tip is in the closed position (down, rotated 90
degree to the left) which closes the contacts of the ZIF connector.
Soldering the tip into a DUT is straightforward, but some of the traditional
soldering techniques that are typically used on larger components will not work
well here. Holding the leads on the ZIF tip in place while applying the soldering
iron and adding solder requires the use of three hands.
The following is an overview of the recommended soldering techniques:
1
Add some solder to the DUT connection points. There should be enough solder
to provide a good fillet around the ZIF tip leads, but not so much as to create a
big solder ball. A fine MetCal (or equivalent) soldering tip should be used along
with some 11 or 15mil solder.
2
Using a rosin flux pen, coat the solder points with flux. The flux core solder
does not provide enough flux for this small scale soldering. Also, put flux on
the tips of the leads of the ZIF tip.
3
Clean the soldering tip well, then add a little bit of solder to the tip. It may take
several tries to get just a little bit of solder right at or near the tip of the
soldering iron. The solder on the tip keeps the soldering iron tip from pulling
solder on the DUT connection points.
4
Position a lead of the ZIF tip on top of one of the target points, then briefly
touch the soldering iron tip to the joint. The thermal mass of this joint is very
small, so you don’t need to dwell on the joint for very long. The flux that was
added to the joint should produce a good, clean solder joint. If you do not get a
good, shinny, strong solder joint, then there was either not enough flux or the
joint was heated too long and the flux boiled off.
5
Repeat step 4 for the other lead of the ZIF tip.
6
There is a possibility that if a lead of the ZIF tip is inserted into a large ball of
solder that is heated excessively with a soldering iron, the solder joint holding
the lead onto the ZIF tip PC board could flow and the lead would come off
destroying the ZIF tip. Only the first third of the lead or so needs to be soldered
to the target point.
