Hello HUFIPUFI, welcome to the forum!
Around the Carpiquet airfield there was a battle around 4-5 July 1944.In position there was the I./26 SS Grenadier Regiment and some units of the 12SS Panzer Regiment, the 9.Kompanie and the 4.Kompanie held as reserve.
I./26 suffered high losses both in killed,wounded and missing, specially the 3.Kompanie who lost 75men and was virtually destroyed,so it's very possible that your dad was in the 3./26. If you got some details, they could be helpful.
Otherwise, you can do a research to the Deutsche Dienststelle: http://dd-wast.de/frame_e.htm