NIS3001 ON Semiconductor, NIS3001 Datasheet - Page 14

• Manufacturer Part Number: NIS3001
• Description: Integrated Driver And Mosfet Power Chip For Synchronous Buck Controllers
• Manufacturer: ON Semiconductor

Thermal/Electrical Vias
improve electrical and thermal performance. If vias are
required on the larger die attach pads, our recommendation
is to use filled−vias. Filled−vias will help prevent the solder
from flowing down into the holes, thereby reducing the
solder volume required for the solder joint of this die attach
pad. Filled−vias are normally filled with some type of
conductive epoxy.
size be less than or equal to 0.25mm(10 mils). The number
of vias placed over the die attach pad is also critical and
should not exceed 25% of the total exposed area of the
copper pattern. In other words, excessive through−hole
vias will allow the solder to flow down into the via and
thereby decrease the solder volume needed to have a
sufficient solder joint. These vias can be plugged with
solder mask material to avoid soldering wicking.
NIS3001 Board Mounting Process
defining and controlling the following processes:
located below.
PCB Solderable metallization
which are used for PCB surface mount devices. In either
case, it is imperative that the plating is uniform,
conforming, and free of impurities to insure a consistent
solderable system.
12X
Vias are normally placed on the larger die attach pads to
If through−hole vias are used, we recommend that the via
The board mounting process is optimized by first
Recommendations for each of these processes are
There are two common plated solderable metallizations,
0.789
1. Creating and maintaining a solderable
2. Choosing the proper solder paste.
3. Screening/stenciling the solder paste onto the
4. Placing the package onto the PCB.
5. Reflowing the solder paste.
6. Final solder joint inspection.
2X
metallization on the PCB contacts.
PCB.
2.169
1.612
2X
0.356
12X
NIS3001 Footprint
Figure 19. Recommended PCB Layout for NIS3001 footprint
1.689
2X
4X
R0.380
3.096
4X
1.612
3.261
2X
http://onsemi.com
4X
2.861
3.439
NIS3001
14
0.789
Solderability Preservative coating (OSP) over the copper
plated pad. The organic coating assists in reducing
oxidation in order to preserve the copper metallization for
soldering.
consists of plated electroless nickel over the copper pad,
followed by immersion gold. The thickness of the
electroless nickel layer is determined by the allowable
internal material stresses and the temperature excursions
the board will be subjected to throughout its lifetime. Even
though the gold metallization is typically a self−limiting
process, the thickness should be at least 0.05 mm thick, and
not consist of more than 5% of the overall solder volume.
Having excessive gold in the solder joint can create gold
embitterment which may affect the reliability of the joint.
Solder Type
a Type 3 or smaller sphere size is recommended. The
WS3060 has a water−soluble flux for cleaning. Cookson
Electronics’ PNC0106A can be used if a no−clean flux is
preferred.
Solder Screening onto the PCB
commonly used in the industry. The recommended stencil
thickness to be used is 0.075 mm (0.003 in) and the
sidewalls of the stencil openings should be tapered
approximately 5 degrees to facilitate the release of the
paste when the stencil is removed from the PCB. Note that
a 0.127 mm (0.005 in) thick stencil may be used also, but
will require smaller stencil openings to reduce the amount
of solder applied to equal the amount of solder applied
using the 0.075 mm thick stencil.
should be the same size as the pad size on the package.
However, in cases where the die pad is soldered to the PCB,
the stencil opening must be divided into smaller openings
4.568
The first metallization consists of an Organic
The second recommended solderable metallization
Solder paste such as Cookson Electronics’ WS3060 with
Stencil screening the solder onto the PCB board is
For a typical edge PCB terminal pad, the stencil opening
Recommended PCB Pattern for NIS3001 Footprint
1.612
0.356
3.658
6.592
1.612
3.261
9.840