The Indian Electrolytic Capacitor industry has emerged stronger, after successfully battling the threat from cheap Chinese imports. This sector is poised to show a robust growth, once the present consolidation phase is over. Aluko recognizes this trend, and has taken a conscious decision to label the present decade as "Focus India". As part of its commitment to support Indian capacitor manufacturers, Vedic Systems organized a 1-day seminar at The Sagar Plaza in Pune. Mr. T. H. Yoon (President - WTS), Mr. S. H. Kim (Manager - Aluko Technical Development Team) and Mr. Kevin.
Kim (Area Sales Manager - WTS) were invited from Korea to make a presentation on the following topics:
After a sumptuous lunch, our visitors attempted to answer a few questions.
|Mr. Joshi of B. C. Components While designing the Capacitor, which table should be followed? EIAJ or ALUKO? (this has a direct impact on the cost of the capacitor in terms of µF/cm2)|
|EIAJ method is the Japanese standard, and requires a high oxide layer. Also, it is mandatory to have high foil purity for EIAJ method. For GPP capacitors, ALUKO method is better. Every capacitor manufacturer follows a different test method. If manufacturer can furnish details (voltage and capacitance) of the existing foil, then ALUKO can suggest a suitable replacement.
Mr. S. H. Kim mentioned that they would be integrating values of Aluko and EIAJ test methods into one common table, for the benefit of capacitor manufacturers. This means that the EIAJ method would get a further boost as the accepted standard. In line with this trend, Vedic Systems will mail a comprehensive write-up on the EIAJ test method, to all participants. However, it is to be noted that the EIAJ method, conceptualized in 1991, does not check the Copper content of the foil, and only JCC and Aluko do this. For instance, the new D series cathode foils launched by Aluko, have similar characteristics as the C series, except that the copper is washed out. Lower Copper content enhances the life of the capacitor.
|Mr. Sohoni of B. C. Components Is there a thumb rule to determine the tan d of foil, before capacitor assembly is done (so that the best foil can be chosen for specific applications)?|
|Use of LCR meter was recommended. However, this method can only be used after stitching is done, and is not very useful in foil selection. In view of Mr. S. H. Kim's limited experience in manufacturing capacitors, the matter will be referred to Mr. Y. S. Kim (Technical Director of Aluko).|
|Mr. Sohoni of B. C. Components Is there a minimum width for slitting? KDK suggests slitting above 5 mm.|
|As such, Aluko foils are comparable to JCC and KDK in most aspects (such as composition and thickness), and customers are requested to use similar benchmarks during production. For instance, if KDK recommends that slit width should not go below 5 mm for the 90 micron series, manufacturers should follow the same guidelines for Aluko foils. Our principals also provided some vital parameters (relating to slitting and stitching) to enhance the life of the slitter and stitching machines, and not disturb the electrical parameters. These are:
(a) Relation between bottom plate + knife and foil.
(b) Depth of knife should be between 0.3~0.5 mm. Bottom plate should be round. After cutting 80,000 M2 of Anode foil and 200,000 M2 of cathode foil, knife should be changed.
(c) Stitching is directly connected to contact resistivity. The foil must be soft enough during this process.
(d) Correlation between thickness of tab and thickness of foil is important.
(e) In Korea, angle of the knife is also controlled for best results.
|Mr. Jaidas of Keltron For forming, ALUKO applies 29 V for 25 WV capacitors. Is this correct?|
Yes. But, 3 critical parameters are to be noted.
Vf = Standard Forming voltage
Vt = Actual measured voltage
Vfe = Actual voltage applied during forming
Vfe = Vf / 1.21 (Correlation)
For WV = 25, Vf = 33 V (at 850 C), Vt = 33 V, Vfe = 29.5 V.
Some Japanese manufacturers apply Vfe of 32 V. They have higher FV and Breakdown voltage and therefore, a high withstanding voltage. It is upto the customer to estimate the cost implications of using a higher Vf.
|Mr. Jaidas of Keltron Any experience in using Ammonium Succinate instead of Ammonium Adipate|
|Mr. Jaidas of Keltron Is foil type FB106A suitable for slit width of 5 mm?|
|Most Korean manufacturers drop down to 8 mm. For 5 mm, slitting and stitching parameters need to be monitored very carefully.|
|Mr. Narasimha Rao of Incap Recounted problems in taping of cathode foils, almost 4~5 years back, due to Blackish powder on the surface. What steps has ALUKO taken to eradicate this?|
|Problems were caused due to erratic quality of the raw foil (procured from a Japanese supplier). The composition of the foil resulted in a blackish powder appearing on the surface post etching. Aluko decided to switch the supplier and also, put extra focus on in-house R & D to deliver superior cathode foils. Though Aluminium content was reduced, this was not supplemented with copper. Instead Mn was used. The results were astounding. The blackish powder problem was totally eliminated. Mechanical characteristics of the foils were found to be far superior allowing use for high speed assemblies. Most important, low copper foils were suitable for AC etching, which is superior to DC technology.|
|Mr. Narasimha Rao of Incap DB954A foils were found unsuitable for stitching at widths below 5 mm.|
|Tensile strength has been improved due to a.m. steps, and heat treatment of the foils|
|Mr. R. K. Kaul of Punsumi Punsumi had observed stability problems, across the length of foil type FB105A, post forming. This problem was not observed in etched foil type DB903A. Does the difference in Pit size between the 2 foils have an impact on the stability?|
|Pit depth is directly proportional to the total thickness of the foil. Since Aluko does AC etching, 33.33% of the raw Al foil is etched on each side. This correlation holds true for the 90 micron and 100 micron series. The difference in pit size between the 2 foils is nominal, and should not impact the forming stability. However, in absolute terms, FB105A will have a greater Pit depth and, consequently, higher capacitance value. Our principals could only offer an explanation after checking the forming process used by Punsumi.|
|Mr. Ramchandran of Rescon Does a passive layer exist over the Al Oxide film, for protection?|
|Ammonium Adipate does not give good water resistance. It is possible to add H3PO3 to create a thin phosphate layer, with high water resistance, over the oxide layer. Temperature during the forming process is also critical to maintain Hydrogen Ion concentration (otherwise the capacitance can vary).|
Certain clarifications would be communicated to each customer individually.
Aluko realizes the importance of reducing the size of the final product. Their AC etching and forming process is oriented towards this trend, and has helped Aluko garner a large share of the global foils market. Vedic Systems would continue to organize such seminars, at frequent intervals, so that customers get an opportunity to interact with suppliers.
Finally, we thank all participants for their support and inputs.