MANUFACTURE OF MAGNETIC CORE FOR SIGNAL LINE FILTER

PURPOSE:To avoid and absorb the deformation due to sintering process thereby enabling the polishing process of junction surfaces to be performed easily and accurately by a method wherein a formed body comprising material powder to form a recession lower than both ends of the central part in the rear surface of the substrate fitting flat cable from both sides as if holding the cable connecting electronic equipments is sintered so that junction parts may be polished while fixing the rear surface part of a sintered body. CONSTITUTION:A formed body 12 comprising separated magnetic cores 2a, 2b forming a recession 13 lower than both ends thereof on the central part of the rear surface 7 of a substrate 4 is formed of the material powder of a magnetic body. The recession 13 is formed in arc or square shape in the thickness to be kept lower than both end parts even if the recession is deformed by sintering process. Next, when this formed body 12 is sintered, it is deformed in the direction making the rear surface 7 convex however, it is hardly deformed due to the decrease in the filling up density and even if deformed, the recession 13 can be kept lower than both ends. In such a constitution, when the rear surface is placed on a chuck surface, both ends of the substrate 4 are stabilized by two supporting points to have even surface when both side junction surfaces 6a, 6b are polished furthermore, when two each of separated magnetic cores 2a, 2b are opposingly fixed, the junction surfaces 6a, 6b perfectly fit to each other not to deteriorate the noise absorption effect.