The invention relates to an acid electrolyte for depositing tin-copper
alloys. Said electrolyte comprises one or more alkylsulfonic acids and/or
alkanolsulfonic acids, one or more soluble tin(II) salts, one or more
soluble copper(II) salts, and one or more organic sulfur compounds having
one or more thioether functions and/or ether functions of general formula
--R--Z--R'--(R and R' are the same or different non-aromatic organic
radicals, and Z represents S or O). The invention also relates to a
method, which involves the use of the electrolyte, to the coating
obtained using said method, and to the use of the electrolyte for coating
electronic components.