Multilayer wiring board and method for forming the same

A multilayer wiring board having a lamination of wiring layers and at least an insulating layer, comprising:

• a first insulating layer having a first face;
• a first wiring layer formed on the first face of the first insulating layer, the first wiring layer having a first via land;
• a second insulating layer formed on the first wiring layer;
• a second via land formed on the second insulating layer, and the second via land being formed in face with the first via land;
• a conductive pillar connecting the first via land and the second via land;
• and
• a stress releasing means formed in the first via land or the second via land for reducing a stress when a force is applied perpendicular to a surface of the first via land or the second via land.

A multilayer wiring board having a lamination of a wiring layer and an insulating layer, comprising:

• an insulating layer having a first face and a second face;
• a first wiring layer formed on the first face of the insulating layer, and the first wiring layer having a first via land;
• a second wiring layer formed on the second face of the insulating layer, the second wiring layer having a second via land, and the second via land formed in face with the first via land;
• and
• a conductive pillar connecting the first via land and the second via land,
• wherein a contact portion of an outer side surface of the conductive pillar and a surface of the first and the second via land have a shape for reducing a stress that causes the conductive pillar to peel apart from the first and the second via lands.

A prefabricated material for a multilayer wiring board, comprising:

• a conductor layer;
• a conductive pillar formed on the conductor layer, the conductive pillar having a substantially conical shape and a contact portion located at an outer side surface of the conductive pillar and a surface of the conductor layer, the contact portion having a shape for reducing a stress that causes the conductive pillar to peel apart from the conductor layer;
• and
• an insulating layer formed so that a part of the conductive pillar is exposed on the insulating layer, the insulating layer being made of an uncured insulating resin,
• wherein the height of the conductive pillar h is approximately in the range from 1.2 d to 5 d, wherein d represents the thickness of the insulating layer.

A method for manufacturing a multilayer wiring board, comprising:

• a step of forming a first wiring layer having a first via land with a stress releasing means on a first insulating layer;
• a step of forming a conductive pillar having a substantially conical shape at a region of a conductor layer in face with the first via land when opposed to the first wiring layer;
• a step of arranging the first insulating layer and the conductor layer so as to face the first via land with the conductive pillar;
• and
• a step of pressing the first insulating layer and the conductor layer in the axial direction of the conductive pillar so as to connect the first via land and the conductive pillar.

A method for manufacturing a multilayer wiring board, comprising:

• a step of forming a first wiring layer having a first via land with a stress releasing means on a first face of a first insulating layer;
• a step of forming a conductive pillar having a substantially conical shape on a first via land;
• a step of laminating a second insulating layer made of an uncured resin so that a part of the conductive pillar is exposed;
• a step of opposing the first face of the first insulating layer and a conductor layer;
• and
• a step of pressing the first insulating layer and the conductor layer in the axial direction of the conductive pillar so as to connect the conductive pillar and the conductor layer.

A method for manufacturing a multilayer wiring board, comprising:

• a step of forming a first wiring layer having a first via land with a stress releasing means on a first face of a first insulating layer;
• a step of forming a first conductive pillar having a substantially conical shape on the first via land;
• a step of forming a second conductive pillar having a substantially conical shape at a region of a conductor layer in face with the first conductive pillar when opposed to the first wiring layer;
• a step of arranging a second insulating layer made of an uncured resin intervened between the first insulating layer and the conductor layer so as to face the first conductive pillar with the second conductive pillar;
• and
• a step of pressing the first insulating layer and the conductor layer in the axial direction of the conductive pillar so as to connect the first conductive pillar and the second conductive pillar.

A method for manufacturing a multilayer wiring board, comprising:

• a step of forming a conductive pillar having a substantially conical shape on a first conductor layer so that a contact portion of an outer side surface of the conductive pillar and a surface of the first conductor layer has a shape for reducing a stress that causes the conductive pillar to peel apart from the first conductor layer;
• a step of laminating an insulating layer made of an uncured resin so that a part of the conductive pillar is exposed;
• a step of pressing the conductive pillar in its axial direction so that the exposed part of the conductive pillar is plastically crushed;
• a step of arranging a second conductor layer on the insulating layer;
• a step of pressing the first conductor layer and the second conductor layer such that the first conductor layer and the second conductor layer are connected in the axial direction of the conductive pillar;
• and
• a step of curing the insulating layer.

A method for manufacturing a multilayer wiring board, comprising:

• a step of forming a first conductive pillar on a first conductor layer so that a contact portion of an outer side surface of the first conductive pillar and a surface of the first conductor layer are continuously smooth;
• a step of forming a second conductive pillar on a second conductor layer so that a contact portion of an outer side surface of the second conductive pillar and a surface of the second conductor layer are continuously smooth;
• a step of arranging an insulating layer made of an uncured resin intervened between the first and the second conductor layers so as to face the first conductive pillar with the second conductive pillar;
• a step of pressing the first and the second conductor layers in the axial direction of the conductive pillar so as to connect the first conductive pillar and the second conductive pillar;
• and
• a step of curing the insulating layer.

An electronic element, comprising:

• an electrode formed on a first face of the electronic element;
• and
• a conductive pillar formed on the electrode of the electronic element,
• wherein a contact portion of an outer side surface of the conductive pillar and a surface of the electrode has a shape for reducing a stress that causes the conductive pillar to peel apart from the electrode.

An electronic element package, comprising:

• an electronic element having an electrode formed on a first face of the electronic element;
• and
• a wiring board on which the electronic element is mounted, the wiring board comprising:
• an insulating layer having a first face and a second face, the first face of the insulating layer being faced with the first face of the electronic element,
• a wiring layer formed on the second face of the insulating layer, the wiring layer having a via land, and
• a conductive pillar connecting the via land and the electrode of the electronic element,
• wherein the via land has a stress releasing means.

An electronic element package, comprising:

• an electronic element having an electrode formed on a first face of the electronic element;
• and
• a wiring board on which the electronic element is mounted, the wiring board comprising:
• a first insulating layer having a first face and a second face, the first face of the insulating layer facing the first face of the electronic element,
• a first wiring layer formed on the second face of the first insulating layer, the first wiring layer having a first via land, and
• a first conductive pillar connecting the first via land and the electrode of the electronic element,
• a second insulating layer having a first face and a second face, the first face of the second insulating layer facing the second face of the first insulating layer,
• a second wiring layer formed on the second face of the second insulating layer, the second wiring layer having a second via land, and
• a second conductive pillar connecting the first via land and the second via land,
• wherein the first via land has a stress releasing means.

A method for forming a conductive pillar, comprising the steps of;

• a step of arranging a mask having a through hole onto a conductor layer;
• a step of filling a conductive resin into the through hole of the mask;
• and
• a step of removing the mask and the conductor layer from each other in the normal direction of the conductor layer, thereby forming the conductive resin to have a substantially conical shape on the conductor layer, and wherein a contact portion of an outer side surface of the conductive resin and a surface of the conductor layer has a shape for reducing a stress that causes the conductive resin to peel apart from the conductor layer.