Patent EP-3748673-A3 (EP)
Title: Electronic device with a conductive particle bonding a first pad to a second pad and sinking in a recess in the first pad
Inventor: CHENG PAI-CHIAO
IPC: H01L21/60
Filed: 2020-04-16
Abstract: An electronic device (100) includes a substrate (102), a first pad (108) disposed on the substrate (102), a second pad (110) disposed opposite to the first pad (108), and a conductive particle (112) disposed between the first pad (108) and the second pad (110). The first pad (108) has a recess (116), and a part of the conductive particle (112) sinks in the recess (116). An integrated circuit (IC) chip (104) may be disposed on the second pad (110) and electrically connected with the second pad (110). An anisotropic conductive film (ACF) (115) may be provided for bonding the IC chip (104) onto the substrate (102), wherein the anisotropic conductive film (115) may include an adhesive layer (114) and conductive particles (112, 112'). The conductive particle (112) may include a core (112c) and a shell (112s) surrounding the core (112c), wherein the core (112c) may include resin material or other suitable material and the shell (112s) may include conductive material, such as metal. The IC chip (104) with the second pad (110) may be bonded and pressed to the substrate (102), wherein a first portion (OLP) of the first pad (108) may be pressed to form the recess (116) and the conductive particle (112) may be pressed to have a relatively oval profile and may sink in the recess (116). Alternatively, the top surface (1081) of the first pad (108) may be relatively rough, may have recess-like structure or may have a recess before the bonding process, which may help to fix the conductive particle (112) during the bonding process. The width (W1) of the recess (116) may be smaller than the width (W2) of the conductive particle (112) so that a part of the conductive particle (112) is not contained nor sinks in the recess (116), bringing a better electrical connection effect between the first pad (108) and the second pad (110) and preventing the conductive particle (112) from slipping or rolling in the recess (116). The first pad (108) may be in a multilayer structure and include a first conductive set (CS1) and a second conductive set (CS2) disposed on the first conductive set (CS1), wherein an insulating layer (120) may be disposed on the first conductive set (CS1), having an opening (OP1) exposing a portion of the first conductive set (CS1), the second conductive set (CS2) being directly in contact with the first conductive set (CS1) through the opening (OP1). The first pad (108) may also be in a multilayer structure and include at least one metal layer (CS1) and a conductive protection layer (CPL) disposed on the at least one metal layer (CS1). An insulating layer (118) may be disposed between the substrate (102) and the first pad (108), wherein the insulating layer (118) may be in a multilayer structure which includes a plurality of sub-insulating layers (118a, 118b, 118c) and at least a portion of one of the sub-insulating layers (118a, 118b, 118c) has a different thickness (t1, t2) from another one of the sub-insulating layers (118a, 118b, 118c), wherein the thickness (t1) may correspond to the first pad (108).