PCA8565TS Philips Semiconductors, PCA8565TS Datasheet - Page 22

• Manufacturer Part Number: PCA8565TS
• Description: Real time clock/calender
• Manufacturer: Philips Semiconductors

Philips Semiconductors
15. Soldering
9397 750 10695
Product data
15.1 Introduction to soldering surface mount packages
15.2 Reflow soldering
15.3 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 preferably be kept:
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 220 C for all the BGA packages and packages with a thickness
and packages with a thickness <2.5 mm and a volume 350 mm
thick/large packages
below 235 C for packages with a thickness <2.5 mm and a volume <350 mm
called small/thin packages.
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.
– 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. 01 — 31 March 2003
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
Real time clock/calender
PCA8565
3
so called
2.5mm
22 of 26
3
so