Assembly for placing solder from solder balls on a substrate , comprising (a) a reservoir with a plurality of solder balls ; (b) an exit opening for releasing one single solder ball ; (c) a feeding channel provided between the reservoir and the exit opening for feeding solder balls from the reservoir to the exit opening ; (d) wherein the feeding channel has an opening cross section with a diameter which is larger than the diameter of one of the used solder balls and smaller than the diameter of two of the used solder balls ; (e) a suction channel ending in the feeding channel and having a cross section in the transition range between the suction channel and the feeding channel which is smaller than the cross section of one of the used solder balls ; (f) means for generating a pressure difference between the feeding channel and the suction channel whereby the pressure in the suction channel is smaller than in the feeding channel and a solder ball present in the feeding channel can be sucked in at the transition range of the suction channel ; and (g) control means for controlling the pressure difference in such a way that at least one solder ball is held back at a first pressure difference at the transition range between the suction channel and the feeding channel and the feeding of further solder balls is blocked and is released with a second pressure difference; wherein (h) the feeding channel ends in an exit channel and forms an angle therewith, wherein the exit channel extends vertical are almost vertical and wherein the feeding channel extends essentially horizontal and the movement of the solder balls is caused by the pressure difference, and characterized in that (i) three or more suction channels are in the moving direction of the solder balls consecutively connected to the feeding channel and the control means are configured in such a way that the solder ball on the side of the exit opening can be released while at least one solder ball can be held back at one of the other suction channels. (a) a reservoir with a plurality of solder balls ; (b) an exit opening for releasing one single solder ball ; (c) a feeding channel provided between the reservoir and the exit opening for feeding solder balls from the reservoir to the exit opening ; (d) wherein the feeding channel has an opening cross section with a diameter which is larger than the diameter of one of the used solder balls and smaller than the diameter of two of the used solder balls ; (e) a suction channel ending in the feeding channel and having a cross section in the transition range between the suction channel and the feeding channel which is smaller than the cross section of one of the used solder balls ; (f) means for generating a pressure difference between the feeding channel and the suction channel whereby the pressure in the suction channel is smaller than in the feeding channel and a solder ball present in the feeding channel can be sucked in at the transition range of the suction channel ; and (g) control means for controlling the pressure difference in such a way that at least one solder ball is held back at a first pressure difference at the transition range between the suction channel and the feeding channel and the feeding of further solder balls is blocked and is released with a second pressure difference; wherein (h) the feeding channel ends in an exit channel and forms an angle therewith, wherein the exit channel extends vertical are almost vertical and wherein the feeding channel extends essentially horizontal and the movement of the solder balls is caused by the pressure difference, and characterized in that (i) three or more suction channels are in the moving direction of the solder balls consecutively connected to the feeding channel and the control means are configured in such a way that the solder ball on the side of the exit opening can be released while at least one solder ball can be held back at one of the other suction channels. <EOS>