Package on Package (PoP) Rework

  • PoP component on a PCB
  • Principle of a flip chip PoP component
  • Cross section of a PoP component

What are the Challenges?

The PoP rework process is similar to standard BGA rework, but because of the vertical assembly, a special clamping solution is necessary. PoP packaging involves the following specific challenges:

  • High-count fine ball pitch (<0,65 mm)
  • Reflow simultaneously on the PCB
  • Applying a sufficient clamping force to lift the component out of liquid solder without lateral movement
  • Reworking different component heights
  • Avoid disturbing neighboring components on densely populated boards
  • Amount of warpage for each package must be limited
  • Precise force control during stacking to avoid shifting of already placed package levels

The Finetech Solution

Remove, Clean, Replace

  • De-soldering a PoP component
  • Soldering a PoP component
  • Preheating the PCB
  • Desoldering the PoP component without affecting neighbored components by using software controlled heating units and qualified tooling
  • Pick up the component with Finetech’s special vacuum activated tweezers
  • Removing residual solder material contactless to avoid any stress to the solder pads
  • Pick up, flux-dip and precise alignment of each package
  • In a final step, simultaneous reflow of all interconnections; packages and PCB

Special Nozzle Design for Quick and Safe Rework

  • Clamping nozzle with actuated tweezers in small clearance between PoP and small passives
  • Front view on nozzle tip
  • Specific nozzle with vacuum controlled tweezers for de-soldering and soldering
  • Nozzle can be adapted easily to different component heights by turning one screw
  • Thin and specially shaped tweezers to clamp the component on every stack level
  • Tweezers distance easily adjustable for rework on densely populated PCBs even in clearance of 0.3 mm to adjacent components
  • Synchronic tweezers actuation is freely software programmable to avoid any stress to non-molten solder joints

Integrated Process Management (IPM)

  • Integrated Process Management (IPM)
  • Principle of process gas integration
  • Operating software for rework

The Integrated Process Management (IPM) is the center piece of a FINEPLACER® system1 - the place where it all comes together. IPM is more than just thermal management. It synchronizes the control of all process modules and their related parameters:

  • Controlled and precisely balanced interaction of top and bottom (pre-)heating and cooling
  • Control of temperature, time, force, power, energy, flow
  • Process-integrated camera and light control
  • Controlled process gas integration for reduced solder contamination, minimized surface tension effects and smooth spherical solder residues

 IPM is very complex, yet easy to access. Via the GUI of the operating software, the user has perfect control of all required adjustments. Just drag 'n drop to define temperature ramps or activate process modules. All settings are represented in only one profile, making for a very intuitive work flow.
 
The operating software provides an ever-growing library of profiles for all kinds of processes. It also offers comprehensive data logging functions essential for statistical process control.

In combination with the system-to-system process transfer capability this is as easy as process development can get.

1 FINEPLACER® core offers co-ordinated top and bottom heating but does not support IPM

Recommended Rework Systems

  • FINEPLACER® coreplus
    Rework of medium-sized boards
  • FINEPLACER® pico rs
    High density rework station

Amongst other factors, the recommended system mainly depends on size and pitch of your component and the required process flexiblity.

Browse our product range or get in contact with your sales contact to figure out the best equipment solution for your needs.

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