ucb1500 NXP Semiconductors, ucb1500 Datasheet - Page 53

• Manufacturer Part Number: ucb1500
• Description: Pci To Ac97 Bridge/host Controller
• Manufacturer: NXP Semiconductors

16. Soldering
Philips Semiconductors
9397 750 07443
Product specification
16.1 Introduction to soldering surface mount packages
16.2 Reflow soldering
16.3 Wave soldering
This text gives a very brief insight to a complex technology. A more in-depth account
of soldering ICs can be found in our Data Handbook IC26; Integrated Circuit
Packages (document order number 9398 652 90011).
There is no soldering method that is ideal for all surface mount IC packages. Wave
soldering can still be used for certain surface mount ICs, but it is not suitable for fine
pitch SMDs. In these situations reflow soldering is recommended.
Reflow soldering requires solder paste (a suspension of fine solder particles, flux and
binding agent) to be applied to the printed-circuit board by screen printing, stencilling
or pressure-syringe dispensing before package placement.
Several methods exist for reflowing; for example, convection or convection/infrared
heating in a conveyor type oven. Throughput times (preheating, soldering and
cooling) vary between 100 and 200 seconds depending on heating method.
Typical reflow peak temperatures range from 215 to 250 C. The top-surface
temperature of the packages should preferable be kept below 220 C for thick/large
packages, and below 235 C small/thin packages.
Conventional single wave soldering is not recommended for surface mount devices
(SMDs) or printed-circuit boards with a high component density, as solder bridging
and non-wetting can present major problems.
To overcome these problems the double-wave soldering method was specifically
developed.
If wave soldering is used the following conditions must be observed for optimal
results:
•
•
•
Use a double-wave soldering method comprising a turbulent wave with high
upward pressure followed by a smooth laminar wave.
For packages with leads on two sides and a pitch (e):
The footprint must incorporate solder thieves at the downstream end.
For packages with leads on four sides, the footprint must be placed at a 45 angle
to the transport direction of the printed-circuit board. The footprint must
incorporate solder thieves downstream and at the side corners.
– larger than or equal to 1.27 mm, the footprint longitudinal axis is preferred to be
– smaller than 1.27 mm, the footprint longitudinal axis must be parallel to the
parallel to the transport direction of the printed-circuit board;
transport direction of the printed-circuit board.
Rev. 03 — 7 July 2000
PCI to AC97 bridge/host controller
© Philips Electronics N.V. 2000. All rights reserved.
UCB1500
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