According to one embodiment, a feedthrough includes a sheet having a hole, where the sheet includes a first material that is a ceramic comprising alumina. The feedthrough further includes a second material substantially filling the hole. The second material is different than the first material and includes platinum and an additive that includes alumina. The first and second materials have a co-fired bond therebetween that hermetically seals the hole. According to another embodiment, a hermetic feedthrough for an implantable medical device includes a sheet having a hole, where the sheet includes a ceramic comprising alumina. The feedthrough also includes a second material substantially filling the hole, where the second material includes a platinum powder mixture and an alumina additive. The platinum powder mixture includes a first platinum powder having a median particle size of between approximately 3 and 10 micrometers and a second platinum powder that is coarser than the first platinum powder and has a median particle size of between approximately 5 and 20 micrometers. The platinum powder mixture includes between approximately 50 and 80 percent by weight of the first platinum powder and between approximately 20 and 50 percent by weight of the second platinum powder. The first and second materials have a co-fired bond therebetween that hermetically seals the hole.La présente invention concerne selon un mode de réalisation une traversée comprenant une feuille présentant un trou, la feuille comprenant un premier matériau qui est une céramique comprenant de lalumine. La traversée comprend en outre un second matériau remplissant sensiblement le trou. Le second matériau est différent du premier matériau et comprend du platine et un additif comprenant de lalumine. Les premier et second matériaux sont reliés par cofrittage, ladite liaison fermant hermétiquement le trou. Selon un autre mode de réalisation, une traversée hermétique pour un dispositif médical implantable co
