Application Note 1. BGA Re-Balling on Expert 4.6 and 9.6. Technology and Application Engineering Martin GmbH

Transcription

1 Application Note 1 BGA Re-Balling on Expert 4.6 and 9.6 Technology and Application Engineering Martin GmbH

2 Introduction Companies using MARTIN EXPERT systems (4.6, 7.6 or 9.xx) may use their systems to reball heavy mass chips controlled and reliable! This short documentation describes the reballing process with the example of the Sony-Playstation3 RSX processor. A high percentage of device malfunction i.e. at Sony-Playstation3, results from poor solder joints at the processors or sockets. Rework of these components demands liability and quality in all steps of rework process. Usually there is a narrow placement condition on the PCB and the BGAreballing procedure itself becomes tricky because of the high thermal mass of the components. When the process of reballing is carried out precisely and controlled it safes stress RSX Processor to the component and benefits the later solder process. According to this description it should be easy to adapt the process to reball BGA chips from different applications. Page 1

3 Install the board in the EXPERT machine and desolder the processor. For desoldering, chose the related Easy Solder profile and remove the chip from the PCB as usual. For detailed information please refer to the manual (Page 29). Install the chip bottomside up in the pcb holder and place it over the IR bottom heater. Apply flux creme sparingly and pre-heat the chip with the IR bottom heater. Page 2

4 Remove old solder and flux residue completely from the RSXpcb. Therefore use the vacuum pen and hot air pen from the EXPERT system. When the board is propper and clean switch off the heater and let the chip cool down. Use flux cleaner spray and remove residue of flux crème from the still hand-warm BGA. According to our experience your reballing success directly depends on the quality of cleaning. Repeat solder removal process if necessary. It might be helpful to use the flux pen to clean blind/black pads. The cleaned pcb is ready for reballing now! First step for reballing is to apply flux crème. We found, that a warm pcb surface eases the uniform and thin application of flux crème. We advise you to work out the cleaning process reasonably fast. Please be carefull with the amount of flux crème too much makes the BGA sticky and creates later problems on in the process. Now the BGA has to be placed in the reballing holder as following: 1. Place the mask properly on the BGA. Verify that it is in perfect contact with the surface. 2. Install the chip with the mask on it into the holder. Check the position of both the pcb and the mask inside the holder. Lock the position by twisting the 4 clamps (yellow arrows). Page 3

5 3. Pour solder balls 600µm onto the mask and settle them into the holes using i.e. the hook tool. Remove spare balls. Verify that all holes are occupied with only one ball to prevent solder problems. Use magnifyer lens or microscope. Check that there are no lost balls on the mask surface as they may recombine with the ones in the holes and aviod removal of the stencil after reflow! Place the complete reballing frame on the glass surface of the IR bottom heater. Choose a position somewhere in the middle of the heated area and place the solder nozzle (42,5x42,4mm²) on top of the chip, see next photo. (For operation with Expert 4.6: Make sure the 15mm solder pen adapter is installed on top of solder pen.) Within Easy Beam Software, click the SOLDER tag. Enter the values from the table below into a new Rapid Profile. Page 4

6 Rising SMD data Time 88s Process data Temp. start 80 C Temp. end 395 C Soldering SMD data Time 125s Air 35l/min Temp. 260 C Process data Temp. hold 355 C Time peak 40 s Cooling SMD data Time 50 s Air 35l/min Process data Time 30 s SMD pickup yes Stacked levels no X time sinking 25 s IR Under heater SMD data Temp.PCB 170 o C. Process data Time rise 95 s Page 5

7 Power start 3000 W Power end 3000 W Power hold 2500 Save the profile and run the soldering process (the values given here are created with an EXPERT 9.6 system operated with EASY Solder Version and can be used for RSX graphic processor with heat sink) You might as well fine-tune the profile to your own specific needs. It should look similar to this one: After the reflow process is finished let the chip cool down and take it out of the frame. Be careful as the tooling might still be hot. Page 6

8 Carefully lift up the mask by hand or with a scraper. The mask should get off smoothly and without any effort. If there was put too much flux crème on the chip the mask might stickon the surface. Do not force the mask to bend to prevent deforming. After the mask is removed, check the proper solder ball structure. Clean the BGA from flux residue carefully using a brush and flux remover. This is what your ready re-balled chip should look like. Now, it s ready for re-soldering. Page 7

9 To achieve a controlled and predictable result, you have to consider the following: 1. For de-/resoldering purposes be sure to use the proper soldering nozzle. It is important to apply a nozzle with the size suited for the chip, otherwise the chip environment could be harmed or the defined hot air field could be diversified. 2. Once you ran your profiler to achieve measurement data, leave the rest to the software and concentrate on enhancement of your experience. Page 8

10 Martin Expert 04.6 Order# : HA Martin Expert 09.6 Order# : DB Reballing mask BGA 45*45mm eco special Order# : LW Reballing-fixture BGA 45*45mm eco with 4 clips and support grid Order# : LW Flux Creme lead free 18g 0506 MA, no clean, REL0, with brush Order# : HT Solder Balls, pcs., lead free BGA Sn96,5Ag3Cu0,5, 600µm (=42g) - Order# : HT Alternative: Solder Balls, pcs., BGA Sn63Pb37, 600µm (= 47g), leaded - Order#: HT PCB clamping holder 40.5 auf HB-05/IR/IRD/IRH/IRF Order# : SF Solder Nozzle BGA 42,5*42,5mm für BGA540/1024 Order# : LW x PCB magnet holder 40.5 for IR/IRD/IRH/IRF and DL/RD Order# : SF Flux Remover Order# : VD Page 9