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参数资料
| 型号： | LSM-2/16-W3 |
| 元件分类： | 电源模块 |
| 英文描述： | 1-OUTPUT DC-DC REG PWR SUPPLY MODULE |
| 文件页数： | 3/12页 |
| 文件大小： | 973K |
| 代理商： | LSM-2/16-W3 |
LSM-16A W3 Models
N O N - I S O L A T E D , W I D E I N P U T S M T D C / D C C O N V E R T E R S
11
Tape & Reel Surface Mount Package
DATEL's LSM series DC/DC converters are the only higher-current (16A)
SMT DC/DC's that can be automatically "pick-and-placed" using standard
vacuum-pickup equipment (nozzle size and style, vacuum pressure and
placement speed may need to be optimized for automated pick and place)
and subsequently reowed using high-temperature, lead-free solder.
Virtually all SMT DC/DC's today are unprotected "open-frame" devices
assembled by their vendors with high-temperature solder (usually Sn96.5/
Ag3.5 with a melting point +221°C) so that you may attach them to your
board using low-temperature solder (usually Sn63/Pb37 with a melting point
of +183°C). Conceptually straightforward, this "stepped" solder approach has
its limitations, and it is clearly out of step with an industry trending toward the
broad use of lead-free solders. Are you to experiment and develop reow pro-
les from other vendors that ensure the components on those DC/DC never
exceed 215-216°C? If those components get too hot, "double-reow" could
compromise the reliability of their solder joints. Virtually all these devices
demand you "cool down" the Sn63 prole you are likely using today.
Figure 6. Reow Solder Prole
DATEL is not exempted from the Laws of Physics, and we do not have magic
solders no one else has. Nevertheless, we have a simple and practical,
straightforward approach that works. We assemble our LSM SMT DC/DC's
using a high-temperature (+216°C), lead-free alloy (Sn96.2%, Ag2.5%,
Cu0.8%, Sb0.5%). The LSM design ensures co-planarity to within 0.004
inches (1001m) of the unit's tin-plated (150 micro-inches) copper leads. See
Mechanical Data for additional information.
The disposable heat shield (patent pending), which has a cutaway expos-
ing the package leads, provides thermal insulation to internal components
during reow and its smooth surface ideally doubles as the vacuum pick-up
location also. The insulation properties of the heat shield are so effective
that temperature differentials as high as 50°C develop inside-to-outside the
shield. Oven temperature proles with peaks of 250-260°C and dwell times
exceeding 2 minutes above 221°C (the melting point of Sn96.5/Ag3.5) are
easily achieved.
HEAT SHIELD OUTSIDE TEMPERATURE
Sn96.5/Ag3.5 Melting Point
Sn63/Pb37 Melting Point
250
200
150
100
50
0
50
100
150
200
250
300
350
400
221
183
PCB TEMPERATURE INSIDE THE HEAT SHIELD
Te
mperature
(
C)
Time (Seconds)
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| LSM221M2D---2225S | 制造商:Surge Components Inc 功能描述:CAP ALUM 220UF 200V ?20% 3000LHRS 22 X 25 - Bulk |
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