1 István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights. OPTIMIZATION OF THE MATERIAL AND COATING OF SOLDERING TOOL Industrial test results of galvanic Ni-layer after soldering cycles partner Materials Science Institute, University of Miskolc

2 Coating development for the stamptool of selective mass soldering Requirements:  long-life,  to reduce service time,  don’t pollute the solder bath,  ensuring the uniform thickness of coating. Applied coating technology: Galvanization (Ni) In the course of galvanization, a metallic coating is separated from the electrolyte containing the ions of metal to be coated on the surface of part connected to the cathode (negative pole) by means of an external current source. In most cases, the positive pole – the anode – is dissoluble and consists of the coating metal. Object Which kind of coating it is possible? István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

3 1.step Heat treatment Purpose: The stabilization of Ni-layer by means of heat treatment  The stamps coated by galvanic Ni by an industrial partner  The stamps were heat treated at a temperature of 1200°C for 2 hours by using Ar protecting gas  The following Figure is an example of the “thermal profile” of the heat treatment The heat treatment was successful, the galvanic Ni-layer penetrated into the holes of steel grains István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

4 2.step Immersion test Purpose: Investigation of the durability and adequacy of coatings  The load-test of 4 stamps can be performed at the same time  The stamps shall be bolted on a steel plate mounted on a rod  The bolt shall be manually immersed in the solder melted in the pipe-furnace  The time of staying in the solder-bath is: 10 hours, 50 hours, 100 hours and 200 hours (1-2. steps: University of Miskolc) István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

5 The photos taken of the cross-sections show that the thickness of layer does not decrease and it can be seen in the spectrum that it is a homogenous layer. After a loading of 50 hours Photos of cross- section Takaró Example István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

6 Results of 1-2.steps Investigation of a Ni-layer made by galvanic method  After a loading of 10 hours: The soldering material covered perfectly the surface of tool, the moistening is suitable, the Ni-layer follows the surface of tool continuously with a thickness of µm, its adhesion is suitable, no cracks can be observed in it.  After a loading of 50 hours: Nothing changed compared to the loading for 10 hours. A soldering-material cover containing a small quantity of Ni can be found above the Ni-layer.  After an operational loading: The mat Ni-coating was investigated after using the stamps with such coatings during an entire production period (longer than an average period). The surface of tool was covered by a layer containing relatively large Sn crystals and the soldering material is located above this layer. Ni-layer cannot be found on the surface but the traces of Ni can be found when analyzing the layer containing Sn crystals. István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

7 3.step Industrial pre-test Details of the experiment  Industrial immersion test  Sn63Pb37 environment  Examination of stamptools after  3500 cycles  7000 cycles  cycles. Base of the test The Ni layer could be stabilized on the tool stamp by means of the heat treatment and the industrial tests are essential in order to know the exact behaviour of layer developed such a way. Scanning Electron Microscopy was used to the analysis. István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

8 3.step Industrial pre-test N = 100xN = 1000x P: 0,7w%, Mn: 0,69w%, Fe: 64,4w%, Ni: 34,22w% P: 0,75w%, Sn: 76,33w%, Mn: 0,62w%, Fe: 21,27w%, Ni: 1,03w% Pb: 31,23w%, Sn: 68,77w% Pb: 38,85w%, Sn 58,26w%, Fe: 1,29w% After immersion cycles: stable eutectic (with Ni) on the stamptool István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

9 Soldering test 22 stamptool were coated and heat treated. After soldering cycles (in Sn63Pb37 bath) the results were the followings (3 stamptools were analysed): 4.step Industrial test cleaned tools Photos were taken at University of Miskolc István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

10 Results István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights. 1 Pb: 0,79 wt% Sn: 1,22 wt% Fe: 55,03 wt% Ni: 39,29 wt% Cu: 3,67 wt% Sn63Pb37 stamptool

11 Results stamptool 1: Pb: 2,19; Sn: 77,01; Fe: 20,24 István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights. 2: Pb: 0,87; Sn: 3,24; Fe: 80,84; Ni: 13,69; Cu 1,36 3: Pb: 0,79; Sn: 0,35; Fe: 96,32; Ni: 2,54 4: Pb: 0,77, Sn: 0,44; Fe: 98,35; Ni: 0,44 Another analysed stamptool Element, Wt % There is 1-4% Cu next to the surface!

12 We have noticed the discolouration of Ni-layer after heat treatment step.  It may be supposed that Cu-layer was applied under the Ni-layer. Supplement 22 stamptools for soldering test discolouration of Ni-layer István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

13 Conclusions after cycles  There isn’t a separate Ni-layer (because of unwanted Cu-layer?)  Small amount of Ni diffused into the base material  The chances are that a Cu-layer effected the disappearance of Ni-layer  It does no good to test other 19 stamptools after cycles – a new test is required  Before a new test cross-section analysis is necessary on a prepared stamptool  + possibility: heat treatment step of stamptools with an industrial partner Summary István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

14 Thank you for your attention! István Andócsi | TEF2 | 00/00/2010 | © Robert Bosch GmbH All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.