多层陶瓷电容(MLCC)应用注意事项

Wellford 深圳市维孚电子有限公司

多层陶瓷电容（MLCC）应用注意事项

一、 储存

为了保持MLCC的性能，防止对MLCC的不良影响，储存时请注意以下事项： 1、

2、

3、 室内温度5～40℃，湿度：20％～70％RH； 无损害气体：含硫酸、氨、氢硫化合物或氢氯化合物的气体； 如果MLCC不使用，请不要拆开包装。如果包装已经打开，请尽可能地重新封上。编

带装产品请避免太阳光直射，因为太阳光直射会使MLCC老化并造成其性能的下降。请尽量在6个月内使用，使用之前请注意检查其可焊性。

二、 手工操作

MLCC是高密度、硬质、易碎和研磨的材质，使用过程中，它易被机械损伤，比如开裂和碎裂（内部开裂需要超声设备检测）。MLCC在手持过程中，请注意避免污染和损伤。手工操作时，建议使用真空挑拣或使用塑料镊子挑拣。

三、

预热

焊接过程中，为了减小对器件的热冲击，精确控制的预热是很有必要的。温度的上升率请不要超过4℃/秒，设预热好的温度与焊接最高温度的温度差为ΔT，则对于0603、0805、1206等尺寸的MLCC, 最好ΔT≤100℃，对于1210、1808、1812、2220、2225等大尺寸的MLCC，最好ΔT≤50℃。

四、

焊接

手焊时，请使用功率不超过30W且温度可调控的烙铁，烙铁头尖的直径不要超过1.2毫米。焊接过程中，请不要用烙铁头直接接触陶瓷体，烙铁的温度不要超过260℃。

对于大尺寸的MLCC，比如1210、1808、1812、2220、2225等，不推荐使用波峰焊和手焊。

五、 冷却

焊接后，慢慢冷却MLCC和基板至室温，推荐使用空气自然冷却，以减小焊接处的应力。当进行强制冷却时，温度下降率请不要超过4℃/秒。

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Wellford 深圳市维孚电子有限公司

六、 清洁

所有焊接残留物都必须使用合适的电子级别的蒸发清洁解决方案清除，因为污物会造成电解表面的腐蚀。使用超声波清除的解决方法最好，适当的清洁系统的选择要考虑很多因素，包括器件、焊剂以及焊头粘贴和组装方法等，清洁系统清除器件底部焊剂和污物的能力很重要。

附1.推荐焊接参数

附2.推荐焊盘尺寸

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APPLICATION NOTES

STORAGE

To prevent the damage of solderability of terminations, the following storage conditions are recommended:

?ambient temperature less than 40℃ ?relative humidity less than 70% RH.

?no harmful gases containing sulfur or chlorine.

Packaging should not be opened until the capacitors are required for use. if opened, the pack should be re-sealed as soon as is practicable. Taped product should be stored out of direct sunlight, which might promote a deterioration in tapeor adhesion performance. The capacitors should be used within 6 months. Checked the solderability before use.

HANDLING

Chip capacitors are dense, hard, brittle, and abrasive materials. They are liable to suffer mechanical damage, in the form of cracks or chips. Chip Capacitors should be handled with care to avoid contamination or damage. The use of vacuum pick up or plastic tweezers is recommended for manual placement. Tape and reeled packages are suitable for automaticpick and placement machines. PREHEAT

In order to minimize the risk of thermal shock during soldering, a carefully controlled preheat is required. The rate of preheat should not exceed 4℃ per second and the final preheat temperature should be within 100℃ of the soldering temperature for small chips

such as 0402, 0603, 0805 and 1206, within 50℃ of the soldering temperature for bigger chips such as 1210, 1808, 1812,2211, 2220, and 2225, etc.

SOLDERING

Use middy activated rosin RA and RMA fluxes do not use activated flux. The amount of solder in each solder joint should be controlled to prevent the damage of chip capacitors caused by the stress between solder, chips, and substrate.

Hand soldering with temperature-controlled iron not exceeding 30 watts and diameter of tip less than 1.2mm is recommended, tip of iron should not contact the ceramic body directly, and the temperature of iron should be set to not more than 260℃.

For bigger chips such as 1210, 1808, 1812, 2211, 2220 and 2225 etc. wave soldering and hand soldering are no recommended.

Recommended soldering profiles as following:

SolderingReflow

Wave

Solder Temp-(T) 235-250℃ 230-250℃ Chip Size 0603,0805,1206

1210,1808,1812,2211,2220,2225

Soldering Time(t)

<15 sec. <5 sec.

△T 100℃ 50℃

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COOLING

After soldering, cool the chips and the substrate gradually to room temperature.

Natural cooling in air is recommended to minimize stress in the solder joint. A cooling rate not exceeding 4℃ per second should be used when forced cooling is necessary.

CLEANING

All flux residues must be removed by using suitable electronic-grade vapor-cleaning solvents to eliminate contamination that could cause electrolytic surface corrosion.

Good results can be obtained by using ultrasonic cleaning of the solvent. The choice of the proper system is dependent upon many factors such as component mix, flux, and solder paste and assembly method. The ability of the cleaning system to remove flux residues and contamination from under the chips is very important.

RECOMMENDED PAD DIMENSIONS (for reflow soldering)

Chip Size0603 0805 1206 1210 1808 1812 2211 2220 2225

A

B

Unit : mm (inches)

C

0.6~0.7(0.024~0.028) 0.6~0.7(0.024~0.028) 0.8~0.9(0.032~0.035) 1.0~1.2(0.039~0.047) 1.2~1.4(0.047~0.055) 1.2~1.4(0.047~0.055) 0.5~1.3(0.020~0.051) 1.4~1.6(0.055~0.062) 1.4~1.6(0.055~0.062)

0.6~0.8(0.024~0.032) 0.6~0.8(0.024~0.032) 1.0~1.2(0.039~0.047) 0.8~1.1(0.032~0.043) 2.2~2.4(0.087~0.094) 1.0~1.4(0.039~0.055) 2.0~2.4(0.080~0.094) 1.8~2.3(0.071~0.091) 2.8~3.4(0.110~0.134) 1.4~1.8(0.055~0.071) 3.0~3.5(0.118~0.138) 2.3~3.0(0.091~0.118) 2.7~4.2(0.106~0.165) 2.6~3.0(0.102~0.118) 4.0~4.6(0.157~0.181) 3.5~4.8(0.137~0.188) 4.0~4.6(0.157~0.181) 3.5~4.8(0.137~0.188)

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