收藏本站
■ PRECAUTIONS
Precautions on the use of Multilayer chip varistors.
3. Considerations for automatic placement
◆ Adjustment of mounting machine
1. Excessive impact load should not be imposed on the varistors when mounting onto the PC boards.
Precautions
2. The maintenance and inspection of the mounters should be conducted periodically.
◆ Selection of Adhesives
1. Mounting varistors with adhesives in preliminary assembly, before the soldering stage, may lead to degraded varistor 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 capacitors, 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 de?ection of the board.
（ 2 ） The pick-up pressure should be adjusted between 1 and 3N static loads.
（ 3 ） To reduce the amount of de?ection 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 :
Technical
consider-
Single-sided mounting
Double-sided mounting
Not recommended
Recommended
ations
2. As the alignment pin wears out, adjustment of the nozzle height can cause chipping or cracking of the varistors because of mechanical impact on the
varistors. 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.
◆ Selection of Adhesives
1. Some adhesives may cause reduced insulation resistance. The difference between the shrinkage percentage of the adhesive and that of the varistors may
result in stresses on the varistors 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 suf ?cient 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 the amount of adhesive is inappropriate to mount varistors on a PCB, that may cause a problem in placement of the component.
Too little adhesive may cause the varistors to fall off the board during the solder process.
Too much adhesive may cause defective soldering due to excessive ?ow of adhesive on to the land or solder pad.
4. Soldering
◆ Selection of Flux
1. Since ?ux may have a signi?cant effect on the performance of varistors, it is necessary to verify the following conditions prior to use ;
（ 1 ） Flux used should be with less than or equal to 0.1 wt% (equivalent to chlorine) of halogenated content. Flux having a strong acidity content should not be
Precautions
applied.
（ 2 ） When soldering varistors on the board, the amount of ?ux applied should be controlled at the optimum level.
（ 3 ） When using water-soluble ?ux, special care should be taken to properly clean the boards.
◆ Soldering
1. Temperature, time, amount of solder, etc. are speci?ed in accordance with the following recommended conditions.
◆ Selection of Flux
1-1. When too much halogenated substance (Chlorine, etc.) content is used to activate the ?ux, or highly acidic ?ux is used, an excessive amount of residue after
soldering may lead to corrosion of the terminal electrodes or degradation of insulation resistance on the surface of the varistors.
1-2. Since the residue of water-soluble ?ux is easily dissolved by water content in the air, the residue on the surface of varistors in high humidity conditions may
cause a degradation of insulation resistance and therefore affect the reliability of the components. The cleaning methods and the capability of the machines
used should also be considered carefully when selecting water-soluble ?ux.
◆ Soldering
1-1. Preheating when soldering
Heating : Ceramic chip components should be preheated to within 100 to 130 ℃ of the soldering.
Cooling : The temperature difference between the components and cleaning process should not be greater than 100 ℃ .
Ceramic chip varistors are susceptible to thermal shock when exposed to rapid or concentrated heating or rapid cooling. Therefore, the soldering process
must be conducted with great care so as to prevent malfunction of the components due to excessive thermal shock.
Recommended conditions for soldering
[Re?ow soldering]
Temperature pro?le
Technical
consider-
ations
Caution
1. The ideal condition is to have solder mass (?llet) controlled to 1/2 to 1/3 of the thickness of the varistor, as shown below :
2. Because excessive dwell times can detrimentally affect solder ability, soldering duration should be kept as close to recommended times as possible.
＊ This catalog contains the typical speci ?cation only due to the limitation of space. When you consider the purchase of our products, please check our speci ?cation.
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.
chipv0102_reli_e-01
12
chipv0102_reli-PRP5
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
VR15AT18A650R VARISTOR 18VDC 30A 150C RAD
VS230A GAS TUBE GDT 230V AXIAL TR
VSHLD-EMR VINCO ETHERNET MP3 RTC SHIELD
VSUPEV2 BOARD EVAL FOR MCP4022,4023,4024
VSUPEV BOARD EVAL VOLT SUPERVISOR SOT23
VTERB-BLK-X2-UT4 LICENSE VITERBI DECODER XP2
VTERB-DECO-XP-N1 IP CORE VITERBI DECODER XPGA
VTP110F POLYSWITCH PTC RESET 1.1A STRAP
相关代理商/技术参数
VR1005DDA080-T 制造商:TAIYO YUDEN 功能描述:Cut Tape 制造商:Taiyo Yuden 功能描述:0
VR100B080CU-2C 功能描述:DC/DC转换器 VRM10VID 1U 80A 12V to 0.8375-1.60V RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压（标称）: 输出端数量:1 输出电压（通道 1）:3.3 V 输出电流（通道 1）:600 mA 输出电压（通道 2）: 输出电流（通道 2）: 安装风格:SMD/SMT 封装 / 箱体尺寸:
VR101 制造商:Fluke Electronics 功能描述:RECORDER VOLTAGE EVENT
VR101/001 制造商:Fluke Electronics 功能描述:RECORDER GERMAN VER FLUKE VR101/001
VR101/003 功能描述:数据记录与采集 VOLTAGE EVENT RECO RoHS:否 制造商:Lantronix 描述/功能:Analog device server 显示器类型:None 电流额定值:
VR101/004 制造商:Fluke Electronics 功能描述:Additional VR101 voltage event recorder
VR101S 制造商:Fluke Electronics 功能描述:RECORDER VOLTAGE EVENT
VR101S/003 功能描述:数据记录与采集 VOLTAGE EVENT RECO RoHS:否 制造商:Lantronix 描述/功能:Analog device server 显示器类型:None 电流额定值: