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  • 电镀层加工常见的有哪些问题你知道吗?
  • 本站编辑:杭州晨诺机械科技有限公司发布日期:2019-06-10 11:12 浏览次数:
1、针孔
 
针孔是因为镀件外表吸附着氢气,迟迟不释放。使镀液无法亲润镀件外表,然后无法电析镀层。跟着析氢点四周区域镀层厚度的添加,析氢点就构成了一个针孔。特点是一个发亮的圆孔,有时还有一个向上的小尾巴“”。当镀液中短少潮湿剂并且电流密度偏高时,轻易构成针孔。
 
 
 
2、麻点
 
麻点是因为受镀外表不洁净,有固体物质吸附,或许镀液中固体物质悬浮着,当在电场效果下抵达工件外表后,吸附其上,而影响了电析,把这些固体物质嵌入在电镀层中,构成一个个小凸点。特点是上凸,没有发亮景象,没有固定外形。总之是工件脏、镀液脏而形成。
 
 
 
3、气流条纹
 
气流条纹是因为添加剂过量或阴极电流密渡过高或络合剂过高而降低了阴极电流效率然后析氢量大。假如那时镀液活动迟缓,阴极挪动迟缓,氢气贴着工件外表上升的进程中影响了电析结晶的陈列,构成自下而上一条条气流条纹。
 
 
 
4、掩镀
 
掩镀是因为是工件外表管脚部位的软性溢料没有除去,无法在此处进行电析堆积镀层。电镀后可见基材,故称露底。
 
 
 
5、镀层脆性
 
在SMD电镀后切筋成形后,可见在管脚弯处有开裂景象。当镍层与基体之间开裂,断定是镍层脆性。当锡层与镍层之间开裂,断定是锡层脆性。形成脆性的缘由多半是添加剂,亮光剂过量,或许是镀液中无机、有机杂质太多形成。
 
 
 
6、气袋
 
气袋的形成是由于工件的形状和积气条件而形成。氢气积在“袋中”无法排到镀液液面。氢气的存在阻止了电析镀层。使积累氢气的部位无镀层。在电镀时,只要注意工件的钩挂方向可以避免气袋现象。如图示工件电镀时,当垂直于镀槽底钩挂时,不产生气袋。当平行于槽底钩挂时,易产生气袋。
 
 
 
7、塑封黑体中央开“锡花”
 
在黑体上有锡镀层,这是由于电子管在焊线时,金丝的向上抛物形太高,塑封时金丝外露在黑体表面,锡就镀在金丝上,像开了一朵花。不是镀液问题。
 
 
 
8、“爬锡”
 
在引线与黑体的结合部有锡层,像爬墙草一样向黑体上爬,锡层是树枝状的疏松镀层。这是由于镀前处理中,用铜刷刷洗SMD框架,而磨损下来的铜粉嵌入黑体不容易洗掉,成为导电“桥”,电镀时只要电析金属搭上“桥”,就延伸,树枝状沉积爬开来与其他的铜粉连接,爬锡面积越来越大。
 
 
 
9、“须子锡”
 
在引线和黑体的结合部,引线两侧有须子状锡,在引线正面与黑体结合部有锡焦状堆锡。这是由于SMD框架在用掩镀法镀银时,掩镀装置不严密,在不需要镀银的地方也镀上了银。而在塑封时,有部分银层露在黑体外面。而在镀前处理时银层撬起,镀在银上的锡就像须子一样或成堆锡。克服银层外露是掩镀银技术的关键之一。
 
 
 
10、橘皮状镀层
 
当基材很粗糙时,或者前处理过程中有过腐蚀现象或者在Ni42Fe+Cu基材在镀前处理时,有的铜层已除去,而有的区域铜层还没有退除,整个表面发花不平滑。以上情况都可能造成镀层橘皮状态。
11、凹穴镀层
 
镀层表面有疏密不规则的凹穴呈“天花脸”镀层。有二种情况可能形成“天花脸”镀层。
 
(1)有的单位用玻璃珠喷射法除去溢料。当喷射的气压太高时,玻璃珠的动能惯性把受镀表面冲击成一个个的小坑。当镀层偏薄时,没有填平凹坑,就成了“天花脸”镀层。
 
(2)基体材料合金金相不均匀,在镀前处理过程中有选择性腐蚀现象。电镀后没有填平凹穴,就成“天花脸”镀层。
 
 
 
12、疏松树枝状镀层
 
在镀液脏,主金属离子浓度高,络合剂低,添加剂低,阴阳极离的太近,电流密度过大,在电流区易形成疏松树枝状镀层。疏松镀层像泡沫塑料,树枝状参差不齐,可用手指抹落镀层。
 
 
 
13、双层镀层
 
双层镀层的形成多半发生在镀液的作业温度比较高,在电镀过程中把工件提出镀槽而又从新挂入续镀。这过程中,如果工件提出时间较长,工件表面的镀液由于水分蒸发而析出盐霜附在工件上,在续镀时盐霜没有来得及溶解,镀层就镀在盐霜表面,形成双层镀层,好像华富饼干,两层镀层中夹入着一层盐霜。
 
避免双层镀层,可以在续镀前先把工件在镀液中晃动几秒钟,让盐霜溶解后再通电续镀。
 
 
 
14、镀层发黑
 
镀层发黑的主要原因是镀液金属杂质和有机杂质高,特别在低电流密度区镀层更黑;在添加剂不足的情况下,在大受镀面积的中部也会出现黑色镀层;温度太低离子活动小,在电流偏高时也会形成灰黑色的镀层。处理金属杂质,可用瓦楞板作阴极,01-0.2A/dm2电解。处理有机污染,可用3-5克/升,活性炭处理。用颗粒状的,先用纯水洗过。
 
 
 
15、钝态脱皮
 
Ni42Fe合金是容易钝态的。镀前活化包括两个化学过程,一个是氧化过程,一个是氧化物的溶解过程。若氧化过程不充分或氧化物来不及溶解掉,受镀表面仍有氧化物残渣,镀层就会脱皮或粗糙。
 
 
 
16、置换脱皮
 
若同一工件上有二种不同的材质组成。例如,铜基材表面是镀镍的,而切剪成形后切口上是露出铜质的。则当强蚀槽中铜离子增加到一个极限值时,镍层上容易产生置换铜层。有了置换铜,镀锡后就会造成锡层脱皮。这种情况下只能勤更新强蚀药水来避免置换脱皮。
 
 
 
17、油污染脱皮
 
若镀前处理中油未除干净,则电镀加工时有油污染的区域就没有镀层,即使有镀层覆盖也是假镀,镀层与基材没有结合力,像风疹块一样一块块隆起,一擦就脱落。   
 
 
 
18、有的工件外表有黑色斑迹。
1, the pinhole
 
 
 
Pinhole is because the surface of the plating adsorbed hydrogen, slow release. So that the solution can not be wet plating surface, and then can not electrochemical coating. With the addition of coating thickness around the hydrogen development point, the hydrogen development point constitutes a pinhole. It features a shiny round hole and sometimes a small upward tail. When the short damp agent in plating liquid and current density on the high side, easily constitute pinhole.
 
 
 
 
 
 
 
2, pitting
 
 
 
The spot is due to the appearance of the plating is not clean, there is a solid adsorption, perhaps the plating solution of solid suspension, when the effect of the electric field arrived at the surface of the workpiece, adsorption on it, and the impact of electrochromatography, the solid material embedded in the plating, a small convex point. It is characterized by a convex, non-luminous scene and no fixed shape. In short, the workpiece dirty, dirty bath and formed.
 
 
 
 
 
 
 
3. Airflow fringe
 
 
 
Because of the excess additive or the high cathode current density or the high complexing agent, the cathode current efficiency is reduced and the hydrogen evolution quantity is large. If at that time the plating liquid activity is slow, the cathode moves slowly, the hydrogen sticks the workpiece surface to rise in the process of affecting the display of electrodialysis crystals, constitute the bottom up stream stripes.
 
 
 
 
 
 
 
4, mask plating
 
 
 
The reason for the mask plating is that the soft overflows on the surface of the workpiece pin have not been removed, and electrochemical deposit cannot be carried out here. After electroplating visible substrate, it is known as the bottom.
 
 
 
 
 
 
 
5, coating brittleness
 
 
 
After SMD plating, the cracks were observed at the bend of the pin. When the nickel layer and the matrix crack, it is determined that the nickel layer brittleness. When the tin layer and the nickel layer crack, it is determined that the tin layer brittleness. The cause of the formation of brittleness is mostly additive, bright agent excess, perhaps the plating solution inorganic, organic impurities too much formation.
 
 
 
 
 
 
 
Six airbags,
 
 
 
The formation of air bags is due to the shape of the workpiece and the gas storage conditions. Hydrogen accumulated in the "pocket" cannot be discharged to the plating level. The presence of hydrogen prevents electroplating. Make hydrogen accumulation site without coating. In electroplating, as long as pay attention to the direction of the workpiece hook can avoid air bag phenomenon. As shown in the figure, when the workpiece is hooked perpendicular to the bottom of the plating bath, no air bag will be produced. When hooked parallel to the bottom of the trough, easy to produce air bags.
 
 
 
 
 
 
 
7, plastic black body center open "tin flower"
 
 
 
There is tin coating on the black body, which is due to the electron tube in the welding line, the gold wire up parabolic shape is too high, when molding gold wire exposed on the surface of the black body, tin plating on the gold wire, like a flower. It's not a bath problem.
 
 
 
 
 
 
 
8. "tin climbing"
 
 
 
At the junction of the lead and the black body, there is a tin layer, which climbs up the black body like a wall grass, and the tin layer is a loose, dendritic coating. This is because in the pre-plating process, the SMD frame is washed with copper brush, and the worn copper powder embedded in the black body is not easy to wash off, becoming a conductive "bridge". As long as the electroconductive metal is put on the "bridge" during electroplating, it will be extended, and the dendritic deposit will climb to connect with other copper powder, and the area of climbing tin is getting larger and larger.
 
 
 
 
 
 
 
9. "beard tin"
 
 
 
At the junction of the lead and the black body, there is a fibrous tin on both sides of the lead, and a burnt tin heap at the junction of the lead front and the black body. This is due to the SMD framework in the method of silver mask plating, the mask plating device is not tight, silver plating in places that do not need silver. And in the molding, there is a part of the silver layer on the outside of the black body. In the pre-plating process, the silver layer is pried up, and the tin is plated on the silver like a piece of silk or piles of tin. It is one of the key techniques to overcome the exposure of silver layer.
 
 
 
 
 
 
 
10, orange peel coating
 
 
 
When the substrate is very rough, or there are corrosion phenomena in the pretreatment process or Ni42Fe+Cu substrate in the plating pretreatment, some copper layer has been removed, and some areas of copper layer has not been removed, the whole surface is not smooth. The above situation may cause the coating orange peel state.
 
11, cavity coating
 
 
 
Coating surface with irregular density of concave "day hualian" coating. There are two possible conditions for the formation of "tianhualian" coating.
 
 
 
(1) some units use glass bead spray method to remove spillage. When the jet pressure is too high, the kinetic inertia of the glass beads impinges the plated surface into small pits. When the coating slant thin, no filling pit, became "day hualian" coating.
 
 
 
(2) the metal phase of the alloy of the matrix material is not uniform, and selective corrosion occurs in the pre-plating process. After electroplating without filling the concave, "day hualian" coating.
 
 
 
 
 
 
 
12, loose dendritic coating
 
 
 
In the dirty plating solution, the main metal ion concentration is high, complexing agent is low, additive is low, the anode and cathode are too close, the current density is too high, easy to form loose dendritic coating in the current area. Loose coating like foam plastic, jagged branches, can be wiped off the coating finger.
 
 
 
 
 
 
 
13, double layer coating
 
 
 
The formation of double layer coating mostly occurs in the bath operating temperature is relatively high, in the process of electroplating the workpiece out of the plating bath and new hanging into continued plating. In this process, if the workpiece is put forward for a long time, the surface of the workpiece due to evaporation of water and precipitation of salt frost attached to the workpiece, in the follow-up plating salt frost did not have time to dissolve, coating on the surface of salt frost, forming a double coating, like hua fu biscuit, two layers of coating sandwiched with a layer of salt frost.
 
 
 
Avoid double layer coating, can be continued before the plating of the workpiece in the plating solution shaking for a few seconds, so that salt frost dissolved after the continuation of electricity plating.
 
 
 
 
 
 
 
14, coating black
 
 
 
The main reason for coating blackening is the high metal impurities and organic impurities in the plating bath, especially in the low current density area of coating blacker; In the case of insufficient additives, in the middle of the large plating area will also appear black coating; Low temperature ion activity is small, high current will also form a grayish black coating. Treatment of metal impurities, can be used as A corrugated plate cathode, 01-0.2A/dm2 electrolysis. Treatment of organic pollution, available 3-5 g/l, activated carbon treatment. Use granulated, first washed with pure water.
 
 
 
 
 
 
 
15. Dull peeling
 
 
 
Ni42Fe alloy is easily blunt. Pre-plating activation includes two chemical processes, one is oxidation process and the other is oxidation process. If the oxidation process is not sufficient or the oxide has no time to dissolve, the plating surface is still oxide residue, coating will peel or rough.
 
 
 
 
 
 
 
16. Replacement and peeling
 
 
 
If the same workpiece has two different material composition. For example, the surface of a copper substrate is nickel-plated, while the cut is exposed from the shear. When the copper ion in the strong erosion groove increases to a limit, the replacement copper layer is easy to be produced on the nickel layer. With replacement of copper, tin coating will cause peeling tin layer. In this case only frequently updated strong corrosion potion to avoid replacement peeling.
 
 
 
 
 
 
 
17, oil pollution peeling
 
 
 
If the pre-treatment oil is not clean, electroplating processing there is no oil pollution area coating, even if there is coating coverage is false plating, coating and substrate without binding force, like a rubella lump lumps, a wipe off.
 
 
 
 
 
 
 
18, some workpiece appearance has black spots.