sc16c652b NXP Semiconductors, sc16c652b Datasheet - Page 38

• Manufacturer Part Number: sc16c652b
• Description: 5v, 3.3 V And 2.5v Dual Uart, 5 Mbit/s Max. ,with 32-byte Fifos And Infrared Irda Encoder/decoder
• Manufacturer: NXP Semiconductors

Philips Semiconductors
12. Soldering
SC16C652B_4
Product data sheet
12.1 Introduction to soldering surface mount packages
12.2 Reflow soldering
12.3 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. Driven by legislation and
environmental forces the worldwide use of lead-free solder pastes is increasing.
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 seconds and 200 seconds depending on heating method.
Typical reflow peak temperatures range from 215 C to 270 C depending on solder paste
material. The top-surface temperature of the packages should preferably be kept:
Moisture sensitivity precautions, as indicated on packing, must be respected at all times.
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:
•
•
•
•
below 225 C (SnPb process) or below 245 C (Pb-free process)
– for all BGA, HTSSON..T and SSOP..T packages
– for packages with a thickness
– for packages with a thickness < 2.5 mm and a volume
below 240 C (SnPb process) or below 260 C (Pb-free process) for packages with a
thickness < 2.5 mm and a volume < 350 mm
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):
– larger than or equal to 1.27 mm, the footprint longitudinal axis is preferred to be
thick/large packages.
parallel to the transport direction of the printed-circuit board;
Rev. 04 — 1 September 2005
Dual UART with 32-byte FIFOs and IrDA encoder/decoder
2.5 mm
3
so called small/thin packages.
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
350 mm
SC16C652B
3
so called
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