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F&S Bondtec

Dear Mr. Kishore,


We would like to share with you some exciting findings from a reference project on the BAMFIT (Bondtec Accelerated Mechanical Fatigue Interconnect Test). Therefore, we would like to use this newsletter as an opportunity to inform you about the results of the comparison of BAMFIT and classic Sheartest.


Problem:

In modern power electronics an enormous amount of heavy-wire bonds are used, which ideally should withstand many years of high thermal cycling. Therefore, special attention is paid to the quality of the bonds. The difficulty with quality assurance is that the life of the bond has to be maximized. However, this is not quite trivial. For this reason, as part of a customer project, we compared the classic sheartest with the patented BAMFIT Test by F&S BONDTEC.

Starting position have been two wire bonders from different manufacturers, which should bond on a substrate with 300 μm aluminum wire. In the following, we will present the results of the tests and what conclusions they give on the quality of the test procedures. The tests were carried out on a 5600CS.



Test:

A classic approach to determine the quality of a bond is a sheartest. The sheartest is a well-known and standardized procedure (MIL, DVS). In addition, it offers good comparability of the values. A disadvantage of this test is, once the adhesion is greater than the shear-through-value of the wire, no difference can be measured.

The following table shows the results of the shear test of the bonds from Bonder#1 and Bonder#2:

WireResult Bonder#1Result Bonder#2
11236,14g1289,12g
21202,08g1253,65g
31185,36g1036,87g
41208,89g1322,08g
51186,97g1232,71g
6976,26g1256,28g
71221,15g1276,11g
81214,34g1069,10g
Avg.1178,90g1216,99g
Std.Dev.83,61105,01

Apparently, the quality of the bond is fine; since the test values of the two bonders are almost identical and therefore valid.
Bonder#1 has a better standard deviation than Bonder#2. Since Bonder#1 is the newly purchased device, this was an additional confirmation.

Usually, with such results, the evaluation of the shear images is often omitted, since the shear values have no abnormalities. In this case, this would have been fatal, as the BAMFIT later showed.

WireResult Bonder#1Result Bonder#2
147750196489
215494249537
375721238708
433737258131
581306224256
6146439175253
788802411128
8651461063151
Avg69299352081,6

The BAMFIT method measures the number of load changes until breakage. Here it became clear that the bonds of Bonder#1 could withstand significantly less load changes. The result is even clearer when looking at the fractional images of the BAMFIT method.




As shown in the figures, Bonder#2 has a much better connection with the substrate. Bonder#1, on the other hand, is lesser connected. Even over a large area, the substrate is visible through the bond.
Fracture image bonder#1
Fracture image bonder#2      



This can be seen much better on the fracture images of the BAMFIT test, than, for example, the Sheartest; since there is no smearing here.       


The yellow marked area in the figure below clearly shows the non-bonded region of the bond, whereas in the case of the sheartest image, this area is not recognizable.

Bonder#1 Sheartest vs Bonder#1 BAMFIT

Result:

The BAMFIT method quickly proved that Bonder#1 did NOT achieve the same bond quality as Bonder#2. BAMFIT showed massive quality differences, which according to sheartest were not existent. The quality of the BAMFIT fracture images is much more meaningful than those from the sheartest.

Best regards
F&S Bondtec Semiconductor GmbH
Siegfried Seidl, MAS
Managing Director/CEO
For further information and questions please contact:
Managing Director/CEO
Siegfried Seidl, MAS
Tel.: +43 (0)7722 67052-8270
Siegfried.Seidl@fsbondtec.at

Sales Manager
Stefan Berger
Tel.: +43 (0)7722 67052-8278
Stefan.Berger@fsbondtec.at

F&S BONDTEC Semiconductor GmbH in Braunau/Austria is an independent company. The company in Braunau produces manual, semiautomatic and automatic machines for each wirebond- and bondtest process. The responsibility of products, development, manufacturing, service and sales is at F&S BONDTEC Semiconductor GmbH in Austria.

F&S BONDTEC Semiconductor GmbH
Industriezeile 49a, A-5280 Braunau/Inn
Tel.:
+43 (0)7722 67052-8270
Fax:
+43 (0)7722 67052-8272
Email:
 info@fsbondtec.at
Web: 
www.fsbondtec.at

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F&S Bondtec Semiconductor GmbH
Industriezeile 49a
5280 Braunau/Inn
Austria