BGA lodding

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Reworking

Martin 09.6 XL machine

Hardware

Gas & power

  • Open the valves on the Nitrogen bottle, the nitrogen line close to the bottle (red lever), and the nitrogen line close to the soldering machine (red lever).
  • Open the valve for the pressurized air behind the white wall cabinet (red lever).
  • Switch on the soldering machine: One switch located on the bottom unit of the soldering machine, on the behind side in the middle. One switch on the DBL (the control unit, on the behind side, a bit to the right.

Unterheater

DBL

Placement Arm

Vacuum nozzles

Hot air nozzles

Lenses

Handling tools

Software - Easy older

Desolder

he default profile is chosen with the hot air nozzle that you select. But for the desoldering, to create a profile, I would have a bit longer time for preheating and soldering, because you don't want to end up with a half desoldered BGA ;) The profiling will shorten the time, and we can't use the desoldered FPGA anyway, since we can't reball it.

There are different profilers to create a BGA profile (rapid, classic, ...). I don't recall wich one it is, but there is one where it asks you to attach temperature probes to the top side of the BGA, and to the underside (as good as you can get it between the solderballs). You can use the teflon tape to attach the probes, but you should avoid air bubbles close to the probes under the tape.

With one of the profilers you can then desolder the BGA, the profile goes through pre heating and soldering state, and there is a button "solder point" which is greyed out in the beginning. During the solder phase this button becomes clickable, and you should use the dentist tools to carefully try to lift the BGA from the board. When the solder is liquid and you can lift the BGA, then you should click "solder point" and take off the BGA. Then comes a cool down phase.

Then you should have a customised profile for this BGA and board.

Rapid profiling

Classic profiling

Optimize profile

Despense

If you are done with test runs of placing, and plan to solder, you can use the "Dispense" to apply flux to the board with the foot pedal and the with brush.

Auto Vision Placer

Before you need to choose the placement nozzle that will hold your BGA with a vacuum. It should be square about 1x1 cm for you BGA. Loosing the silver screw on the arm over the placement nozzle and disconnect the rubber tube.

Start AVP and choose the lens that your BGA fits in. I think the one that fits for you is called 'Maxi BGA'. Then you mark the outline on the PCB, we got the best results with taking the inside edges of the solder placement marks, but in theory you can also take the lands itself. You need to mark two adjacent corners and the opposing edge. Since there is no mark for the edge, you can take the line from the solder placement marks as far to the inside as you can get. When you are happy with the drawn square, you can turn on the vacuum put the BGA on the tip of the placement nozzle. Then you click "nozzle down" and mark the outline of the BGA, again two corners and one edge. Because of the fuzzy corners where the BGAs where cut/broken off, you might have set the cursor that the corner fits to the clean cut edges. THen you can place the BGA, and check if it aligns correctly.

Solder

After the placing from above, you can select the solder part. Before starting the soldering, you should check that the hot air nozzle aligns properly with the BGA, and you might have to move the arm a bit manually to get it aligned (there is a switch to turn the magnet of on the base of the arm). Then you have to check the height, that the solder nozzle doesn't touch the PCB or the BGA. In order to not bend the placement arm, put your thumb under the placement arm, and push down the red part with your pointer. You can adjust the height with the screw on the top. There shouldn't be more then 1mm between the solder nozzle and the board. Then you can click "Solder" and it will ask you if the underheater support and nozzle is in place. This is the last chance to fix it. When you click next, the machine goes through the solder profile. After soldering you can save the report as pdf somewhere (print to pdf printer).

Clean Pad

With the clean pad function the underheater is on, and you can use the hot air pen from the stand next to the PC to clean the solder rests of the PCB, also using the suction pen from the stand. The lands can come off easily if you are not careful. But if you use a new board to solder, you don't need to do this.


ReBalling

The process of attaching new solderballs to a previously desoldered BGA is called reballing. For this we need a small reballing oven, into which the BGA goes, and a mask that corresponds to the ball layout on the BGA.

Dominik 09:03, 26 March 2010 (UTC)