00195982-03_SM_SWS_EN.pdf - 第51页
3 SIPLACE wafer system (SWS) function 3.2 Basic die presentation process Service Manual SIPLACE Wafer System (SWS) 11/2018 51 3.2.4 Ejection procedure Once the die has been centered using the ejector system, it can be re…
3 SIPLACE wafer system (SWS) function
3.2 Basic die presentation process
50 Service Manual SIPLACE Wafer System (SWS) 11/2018
3.2.2 Die attach process
The optional die attach unit is needed for the die attach process.
In this method, the die is placed in the same bottom/top orientation as it was on the wafer foil
("face-up" placement).
The die attach method is the traditionally established die placement procedure. Die attach requires
an additional step to create the connections between the die and the printed circuit board (wiring
connections).
Fig.30: Die attach process steps
The steps in the die attach process are as follows:
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Step 1: Die release
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Step 2: The die is rotated by approx. 130°and transferred to the die attach unit.
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Step 3: The die attach unit rotates the die into the pickup position and transfers it to the place-
ment head. Parallel to this, the next die is picked up by the flip unit.
3.2.3 Die recognition and die positioning
The wafers are fixed to the wafer foil with a specific position and angular tolerance.
It is therefore not possible to place the die reliably in the center of the ejector unit without recogni-
tion and correction. This is particularly important for small dies, in order to ensure reliable ejection.
Furthermore, you may need to process only a selection of dies. A selection can be made by mark-
ing "bad" dies with an ink spot or by using a wafer map file for the relevant wafer.
The following equipment is needed for this process step:
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2 axis wafer table for positioning
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Wafer camera system for the die and for optional ink spot recognition
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Optional wafer map system
3 SIPLACE wafer system (SWS) function
3.2 Basic die presentation process
Service Manual SIPLACE Wafer System (SWS) 11/2018 51
3.2.4 Ejection procedure
Once the die has been centered using the ejector system, it can be released from the wafer foil us-
ing needles and transferred to the flip unit. While the needles release the die from the foil, the wafer
foil is moved towards the ejection system by means of suction.
Fig.31: Die presentation process
The following equipment is needed for this process:
●
Ejection system with exchangeable ejector tool
3.2.5 Pickup process
During the pickup process, the die is transferred to the tool and to the nozzle of the flip unit. The flip
unit transfers the die on it either to the placement head (flip chip process) or to the die attach unit
(die attach process).
The die attach unit rotates the die again and then presents it to the placement head. The following
equipment is needed for this process step:
●
Flip unit
●
Die attach unit (optional)
3 SIPLACE wafer system (SWS) function
3.2 Basic die presentation process
52 Service Manual SIPLACE Wafer System (SWS) 11/2018
3.2.6 Embedded wafer level ballgrid array (eWLB/WLFO) process
Embedded wafer level ballgrid array is a packaging technology which makes it possible to produce
thin components with excellent electrical conduction with a 'chip fan out'. This means that the area
used for the connection pads is larger than the actual silicon, making sufficient space available for
the SMD process.
In this process, the chip components are placed with the active surface pointing downwards ("face
down") on a carrier with double-sided adhesive tape. After placement, this structure is molded.
After the die bond process of the carrier material, wafer structuring processes are used to create
the electrical contacts. In these, the molded area around the silicon is used as the carrier material
for "conductor tracks" ("fan out"). Finally, the components are tested, labeled and, for example,
packed in tapes.
Fig.32: Steps in the embedded wafer level ballgrid array process
1. The thermal release tape is laminated onto the metal carrier.
2. The active side of the wafer is placed face down onto the thermal release tape (flip chip)
3. Molding takes place under pressure, hardening at 150°C
4. Release
5. Redistribution layer (RDL)
6. Balling and single
7. Test, mark, pack