Method for forming bumps, semiconductor device, and solder paste

A bump formation method for forming bumps on a substrate provided with a plurality of electrode pads, comprising the steps of:

• forming a first cover layer over the substrate;
• forming a second cover layer over the first cover layer;
• forming a plurality of openings corresponding to the plurality of electrode pads in the first cover layer and the second cover layer by exposing these to light and developing with an etchant;
• filling each of the openings with metal;
• and
• heating the metal to integrate it with the electrode pads,
• wherein the first cover layer is formed from a material that will be dissolved by the etchant used to develop the second cover layer, and the first cover layer is etched to form the plurality of openings simultaneously with the developing of the second cover layer.

A bump formation method for forming bumps on a substrate provided with a plurality of electrode pads divided into a plurality of groups, comprising the steps of:

• forming a mask having a plurality of openings corresponding to the plurality of electrode pads such that the size is different for each group;
• filling the openings with solder paste;
• forming bumps from the solder paste by heat treatment;
• and
• removing the cover layer from the substrate.

A bump formation method for forming bumps on a substrate provided with a plurality of first electrode pads and a plurality of second electrode pads, comprising the steps of:

• forming a first cover layer in a state in which the plurality of first electrode pads are covered and the plurality of second electrode pads are exposed;
• forming a plurality of first openings in the first cover layer in a pattern corresponding to the plurality of first electrode pads;
• forming a second cover layer so as to cover the first cover layer and the plurality of second electrode pads;
• forming a plurality of second openings in the second cover layer in a pattern corresponding to the plurality of second electrode pads, and forming a plurality of third openings in a pattern corresponding to the plurality of first openings;
• filling the first openings, second openings, and third openings with solder paste;
• and
• forming bumps from the solder paste by heat treatment.

A bump formation method for forming bumps on a substrate provided with a plurality of electrode pads, comprising the steps of:

• holding the substrate on a substrate support;
• forming a cover layer so as to cover at least the substrate;
• forming a plurality of openings in the cover layer in a pattern corresponding to the plurality of electrode pads;
• providing squeegeeing helper means for lessening the difference between the height position of the cover layer on the substrate and the height position of the periphery of the substrate;
• readying a metal paste or metal powder on the cover layer or the squeegeeing helper means;
• moving a squeegee to push the metal paste or metal powder down into the openings;
• heating, melting, and solidifying the metal paste or metal powder to integrate the same on the electrode pads;
• and
• taking away the squeegeeing helper means.

An electronic component, comprising:

• a substrate;
• a plurality of first electrode pads and a plurality of second electrode pads formed on the same surface of this substrate;
• a plurality of first bumps formed in a pattern corresponding to the plurality of first electrode pads;
• and
• a plurality of second bumps formed in a pattern corresponding to the plurality of second electrode pads,
• wherein the surface area of each of the first electrode pads is smaller than the surface area of each of the second electrode pads, and
• the top of each of the first bumps is located higher than the top of each of the second bumps.

An electronic component, comprising:

• a substrate;
• a plurality of first electrode pads and a plurality of second electrode pads formed on the same surface of this substrate;
• a cover layer formed in the region of the substrate where the plurality of first electrode pads are formed, and having a plurality of openings corresponding to the plurality of first electrode pads;
• a plurality of first bumps provided in a pattern corresponding to the plurality of first electrode pads, with spherical portions protruding from the cover layer;
• and
• a plurality of second bumps provided in a pattern corresponding to the plurality of second electrode pads, with spherical portions formed directly on the corresponding second electrode pads,
• wherein the top of each of the first bumps is located higher than the top of each of the second bumps.