■ PRECAUTIONS
Precautions on the use of Multilayer chip Inductors, Multilayer chip inductors for high frequency, Multilayer chip bead Inductors
2. PCB Design
◆Pattern configuration（s Inductor layout on panelized［breakaway］PC boards）
1-1. The following are examples of good and bad inductor layout; SMD inductors should be located to minimize any possible mechanical stresses from board
warp or deflection.
Item
Not recommended
Recommended
Deflection of the board
1-2. To layout the inductors for the breakaway PC board, it should be noted that the amount of mechanical stresses given will vary depending on inductor layout.
An example below should be counted for better design.
Technical
consider-
ations
1-3. When breaking PC boards along their perforations, the amount of mechanical stress on the inductors can vary according to the method used. The following
methods are listed in order from least stressful to most stressful: push-back, slit, V-grooving, and perforation. Thus, any ideal SMD inductor layout must
also consider the PCB splitting procedure.
3. Considerations for automatic placement
◆Adjustment of mounting machine
1. Excessive impact load should not be imposed on the inductors when mounting onto the PC boards.
2. The maintenance and inspection of the mounter should be conducted periodically.
Precautions ◆Selection of Adhesives
1. Mounting inductors with adhesives in preliminary assembly, before the soldering stage, may lead to degraded inductor characteristics unless the following
factors are appropriately checked; the size of land patterns, type of adhesive, amount applied, hardening temperature and hardening period. Therefore, it is
imperative to consult the manufacturer of the adhesives on proper usage and amounts of adhesive to use.
◆Adjustment of mounting machine
1. If the lower limit of the pick-up nozzle is low, too much force may be imposed on the inductors, causing damage. To avoid this, the following points should be
considered before lowering the pick-up nozzle:
（1）The lower limit of the pick-up nozzle should be adjusted to the surface level of the PC board after correcting for deflection of the board.
（2）The pick-up pressure should be adjusted between 1 and 3N static loads.
（3）To reduce the amount of deflection of the board caused by impact of the pick-up nozzle, supporting pins or back-up pins should be used under the PC
board. The following diagrams show some typical examples of good pick-up nozzle placement:
Item
Improper method
Proper method
Single-sided mounting
Double-sided mounting
2. As the alignment pin wears out, adjustment of the nozzle height can cause chipping or cracking of the inductors because of mechanical impact on the
inductors. To avoid this, the monitoring of the width between the alignment pin in the stopped position, and maintenance, inspection and replacement of the
pin should be conducted periodically.
Technical
consider-
ations
◆Selection of Adhesives
1. Some adhesives may cause reduced insulation resistance. The difference between the shrinkage percentage of the adhesive and that of the inductors may
result in stresses on the inductors and lead to cracking. Moreover, too little or too much adhesive applied to the board may adversely affect component
placement, so the following precautions should be noted in the application of adhesives.
（1）Required adhesive characteristics
a. The adhesive should be strong enough to hold parts on the board during the mounting & solder process.
b. The adhesive should have sufficient strength at high temperatures.
c. The adhesive should have good coating and thickness consistency.
d. The adhesive should be used during its prescribed shelf life.
e. The adhesive should harden rapidly.
f. The adhesive must not be contaminated.
g. The adhesive should have excellent insulation characteristics.
h. The adhesive should not be toxic and have no emission of toxic gasses.
（2）When using adhesives to mount inductors on a PCB, inappropriate amounts of adhesive on the board may adversely affect component placement. Too
little adhesive may cause the inductors to fall off the board during the solder process. Too much adhesive may cause defective soldering due excessive
flow of adhesive on to the land or solder pad.
［Recommended conditions］
Figure
0805 case sizes as examples
0.3mm min
a
b
c
100～120μm
Area with no adhesive
＊This catalog contains the typical specification only due to the limitation of space. When you consider the purchase of our products, please check our specification.
For details of each product (characteristics graph, reliability information, precautions for use, and so on), see our Web site (http://www.ty-top.com/) or CD catalogs.
mlci0109_reli_e-01
mlci0109_reli-PRP14
TAIYO YUDEN [ TAIYO YUDEN (U.S.A.), INC ]
