PURPOSE:To directly form the solder bump having a high bump height in an excellent condition on an electrode and to simplify the process of manufacture by a method wherein a substrate is heated up, fused solder is contacted to an electrode part, and supersonic waves are applied at least to the fused solder or on the substrate without providing a bace metal on the electrode. CONSTITUTION:An electrode 33 is exposed from the insulating film 34 with which a substrate is covered, and after said substrate 11 has been heated up, fused solder 23 is contacted at least to the electrode part 33, supersonic waves are applied at least to either of the fused solder 23 and the substrate 11, the natural oxide film present on the surface of the electrode 33 is destroyed, and selectively adhere a solder layer 55 by alloying the electrode 33. For example, after the silicon wafer 11, on which the aluminum electrode 33 is exposed from a passivation film 34, has been maintained at 300 deg.C for 20 minutes, it is dipped into the fused solder 23 jetting out in a solder vessel 21. Then, a supersonic vibrator 25 is inserted into the fused solder 23 located in the vicinity of the silicon wafer 11, supersonic waves are applied to the fused solder 23, nitride gas is made to flow around the fused solder, and the oxidization of the aluminum and the tin of the electrode 33 can be prevented.

Formation of solder bump

PURPOSE: To form bumps having high reliability at every semiconductor element by dipping semiconductor elements, to which aluminum electrodes are shaped, into a palladium solution, activating the surfaces of the electrodes and precipitating nickel on the electrodes through electroless nickel plating. CONSTITUTION: The surface of an Al electrode 12 for a semiconductor element, from which the greater part of the Al electrode 12 is exposed, is pretreated by the diluted solution of nitric acid (or phosphoric acid) and washed. The semiconductor element is dipped into a palladium activator consisting of palladium chloride, hydrochloric acid and water and the precitate 14 of Pd is attached to the surface of the exposed Al electrode 12. The Al electrode 12 is washed to an extent that the Pd precipitate on the surface of the Al electrode 12 for the semiconductor element is not removed, the semiconductor element is dipped into an electroless nickel plating bath and a nickel bump 15 is shaped to the periphery including the Al electrode 12 exposed, and electroless gold plating is executed. Accordingly, the bump having excellent adhesive properties can be formed without having an adverse effect on a substrate and the Al electrode for the element. COPYRIGHT: (C)1988,JPO&Japio

Forming method for bump

The present invention discloses a method for electroless plating of a metal or metal alloy onto a metal or a metal alloy structure comprising a metal such as molybdenum or titanium and alloys containing such metals. The method comprises the steps of activation, treatment in an aqueous solution comprising at least one nitrogen-containing compound or a hydroxy carboxylic acid and electroless plating of a metal or metal alloy.

Method for electroless plating

PURPOSE:To provide a one-pack activating soln. for electroless nickel plating having superior selectivity by adding a palladium ammonium complex and an alkali metal hydroxide. CONSTITUTION:This activating soln. contains a palladium ammonium complex such as Pd(NH3)4Cl2, Pd(NH3)4Br2 or Pd(NH3)4SO4 and an alkali metal hydroxide such as KOH. The complex is present in the soln. in the form of complex ion Pd(NH3)4 . Other complex forming complex ion Pd(NH3)2 may be used as the palladium ammonium complex. A ceramic board having a wiring pattern is immersed in the activating soln. containing such as Pd4Cl4 and KOH at about 40-70 deg.C for about 1-5min to selectively deposit Pd on the pattern and then the board is immersed in an electroless Ni plating soln. A nickel film can be selectively formed on the pattern.

Activating solution for electroless nickel plating

PURPOSE:Partly formed conductor on nonconducting surface is activated by Pd and again activated by Au, then electrolessly Ni plated, thus providing well-adhered Ni plate layer regardless of substrate materials. CONSTITUTION:On a nonconductive substrate 1 such as alumina base ceramic plate or synthetic resin plate, W, Mo, Cu and other metal base paste is printed in the form of wiring pattern 2. For W and Mo, metal paste is fired together with ceramic substrate to be metallized. The printed substrate is immersed into Pd ion solution consisting of PdCl2, HCl and a small amount of EDTA for about 30 seconds to one minute. During the immesion, finely activated Pd 6 is formed on metal surfaces. Then the treated substrate is immersed in gold ion solution consisting of KAu(CN)4, NH4Cl and sodium citrate for about 30 seconds to 3 minutes to form activated Au 7 on Pd layer. Known method is used for Ni electroless plating to obtain Ni layer 3.

Electroless nickel plating

PURPOSE:To provide a method of plating, according to which non-electrolytic nickel plating for conductive or semiconductive layer formed on ceramic substrate is applied by the intermediary of a layer of gold plating, whereby uniform layer of plating, free of separation, can be obtained.

Ootsuka Kenichi

Papers

Electroless nickel plating

Method of plating