This slide show is an overview of several techniques used to rework QFNs. Included is paste printing of the PCB and "bumping" of the component prior to placement of the QFN.

1. QFN Rework
A Primer
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2. Rework Technique
IPC 7711 3.11

3. Rework Technique
IPC 7711 3.11

4. Rework Technique
IPC 7711 3.11

5. Rework Technique
IPC 7711 3.11

6. Step #1
Align and apply
stencil to
device. Roll
solder paste
through
apertures.
Part Bumping Using a Polyimide
Peel-n-Stick Stencil(s)
IPC 7711 5.8.1.2.

7. Step #2
Reflow per solder
mfr’s profile
recommendations
Part Bumping Using a Polyimide
Peel-n-Stick Stencil(s)

8. Step #3
Remove
stencil and
clean.
Surface now
is “bumped”
Part Bumping Using a Polyimide
Peel-n-Stick Stencil(s)

9. Inspection of “bumped” device
Part Bumping Using a Polyimide
Peel-n-Stick Stencil(s)

10. Step #4
Prep land
area on PCB
where device
is to be
placed
Part Bumping Using a Polyimide
Peel-n-Stick Stencil(s)

11. Step #5
Align and
adhere board
stencil on
PCB. Roll
solder paste
into apertures
and clean off
residue.
Part Bumping Using a Polyimide
Peel-n-Stick Stencil(s)

12. Step #6
Place
“bumped”
QFN into
stencil
apertures.
Feel the
“bumps” fit
into the
apertures
Part Bumping Using a Polyimide
Peel-n-Stick Stencil(s)

13. Step #7
Reflow as per
solder paste
manufacturers’
profile
recommendations.
Perform visual
inspection.
Perform X-ray
inspection.
Part Bumping Using a Polyimide
Peel-n-Stick Stencil(s)

14. Print Quality

15. Print Quality

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