Fabrication method and structure of pcb assembly, and tool for assembly thereof

Abstract

A fabrication method and structure for a PBCA, and tool for assembly of the structure. The structure includes a circuit board, at least one first solder joint, a plurality of second solder joints, and an electronic device. The circuit board has a solder mask, having a plurality of openings exposing at least one first pad and a plurality of second pads arranged beyond the first pad, on a surface. The first solder joint has a maximum width J 1 and electrically connects to the first pad. The second solder joints respectively have a maximum width J 2 exceeding J 1 and respectively electrically connect to the second pads. The electronic device has a plurality of third pads, arranged substantially corresponding to the openings, respectively electrically connecting to the first pad and second pads.

1 - 14 . (canceled) 
     
     
         15 . A PCB assembly structure, comprising:
 a circuit board comprising a plurality of first pads and a plurality of second pads wherein the second pads are arranged outside the first pads; and   an electronic device comprising a plurality of third pads arranged corresponding to the first and second pads, the first pads electrically connecting to the corresponding third pads using a plurality of first solder joints, the second pads electrically connecting to the corresponding third pads using a plurality of second solder joints;   wherein a first angle is formed between one of the first solder joints and the corresponding first pad, a second angle is formed between one of the second solder joints and the corresponding second pad, and the first angle is larger than the second angle.   
     
     
         16 . A PCB assembly structure, comprising:
 a circuit board comprising a plurality of first pads and a plurality of second pads, wherein the second pads are arranged outside the first pads, and the sizes of the first and second pads are substantially the same; and   an electronic device comprising a plurality of third pads arranged corresponding to the first and second pads, the first pads electrically connecting to the corresponding third pads using a plurality of first solder joints, the second pads electrically connecting to the corresponding third pads using a plurality of second solder joints;   wherein the volume of the second solder joint exceeds the volume of the first solder joint.   
     
     
         17 . A method for assembling an electronic structure, comprising the following steps:
 providing a circuit board having a plurality of first pads and a plurality of second pads in which the second pads are arranged outside the first pads;   disposing a tool over the circuit board, the tool comprising a metal plate having a plurality of first openings substantially corresponding to the first pads and a plurality of second   openings substantially corresponding to the second pads, wherein the measure of area of the second opening is larger than the measure of area of the first opening;   applying solder paste on the first and second pads through the first and second openings;   separating the tool and the circuit board;   disposing an electronic device over the circuit board, the electronic device comprising a plurality of third pads arranged substantially corresponding to the first and second pads and a plurality of solder bumps electrically connected to the third pads respectively, the solder bumps contacting their corresponding solder pastes respectively;   reflowing the solder bumps and solder paste, wherein the first solder pastes combine with their corresponding solder bumps to form a plurality of melted first solder joints, and wherein the second solder pastes combine with their corresponding solder bumps to form a plurality of melted second solder joints; and   solidifying the first and second solder joints.   
     
     
         18 . The structure as claimed in  claim 15 , wherein the sizes of the first and second pads are substantially the same.