JPWO2021001757A5 - - Google Patents

Claims (14)

A method of mounting and cooling a circuit component having multiple contacts, comprising the steps of:
(i) providing a rigid substrate made of a thermally conductive and electrically insulating material;
(ii) providing a circuit board having an electrically insulating flexible base and electrically conductive traces on the flexible base connecting the circuit components to control and driver circuits; each of said traces terminating in a respective contact pad positioned to align with a respective contact of said circuit component;
(iii) forming blind holes in the flexible base of the circuit board, each blind hole on the flexible base on the side of the circuit board facing the rigid substrate; terminating at each one of said contact pads;
(iv) plating the side of the contact pad exposed by the blind hole and enlarging at least one metallic material to fill the blind hole in the flexible base of the circuit board, thereby forming an electrically and thermally conductive via extending between opposite sides of the flexible base;
( v ) positioning at least a portion of the contact pads on the circuit board on the side of the circuit board facing the rigid board to secure the circuit board to the rigid board;
( vi ) bonding at least a portion of the contact pads on the side of the circuit board facing the rigid substrate to the rigid substrate to establish thermal contact between the bonded contact pads and the rigid substrate; a step;
(vii) placing the circuit component on the circuit board such that the circuit board with the flexible base resides between the circuit component and the rigid substrate;
(viii) soldering the contacts of the circuit component to the vias to provide electrical connections between the contacts of the circuit component and the traces on the circuit board; establishing a thermal connection between at least a portion of and the rigid substrate;
A method, including 2. The method of claim 1, wherein the contact pads of the circuit board are directly connected to the rigid substrate by diffusion bonding or low temperature sintering. forming metal contact pads on the rigid substrate such that the contact pads on the side of the circuit substrate facing the rigid substrate are aligned with the contact pads on the circuit substrate; and 3. A method according to claim 1 or 2, wherein the rigid substrate is bonded by bonding the aligned contact pads thereon and the rigid substrate together. 4. The method of claim 3, wherein the contact pads of the circuit board are connected to the contact pads on the rigid substrate by diffusion bonding. The method of any one of claims 1-4, wherein the plating forming the via is electroless nickel immersion gold (ENIG) plating. A circuit subassembly,
a) a rigid substrate (16) made of an electrically insulating but thermally conductive material;
b) a circuit board (12) mounted to said substrate (16) , said circuit board (12) comprising a base (122) and a plurality of traces (121) connectable to control and driver circuits; a circuit board (12) having: each of said traces (121) terminating in a respective contact pad (123 ) ;
c) a circuit mounted on the circuit board (12) on the opposite side of the rigid board (16) and electrically connected to the traces (121) of the circuit board through the contact pads (123); a component (10) , and
d) filled with electrically and thermally conductive vias (124 ) formed in said circuit board (122) to conduct heat from said circuit component (10) to said rigid substrate (16) ; and a hole (125 ) connecting said trace (121) on said circuit board to said circuit component;
In a circuit subassembly comprising
e) said base (122) of said circuit board (12) is flexible;
f) at least part of the contact pads (123 ) of the circuit board (12) are arranged on the side of the circuit board facing the rigid substrate (16) and bonded to the rigid substrate (16) ;
g) at least a portion of the holes (125) in the flexible base of said circuit board terminating in respective contact pads (123) bonded to said rigid substrate (16) , said contact pads (123) being does not penetrate, and
h) respective vias (124) filling holes in said flexible base of said circuit board are formed as plating on the side of each contact pad facing away from said rigid substrate (16) ; are soldered to respective contacts (101) of said circuit component (10) ,
A circuit subassembly, characterized by: The flexible base (122) of the circuit board (12) has a thickness in the range of 1 μm to 125 μm, 2 μm to 75 μm, 2 μm to 50 μm, 2 μm to 25 μm, 2 μm to 10 μm, or 2 μm to 5 μm. 7. The circuit subassembly of 6. A circuit subassembly according to claim 6 or 7, wherein said rigid substrate (16) further comprises contact pads (161) substantially aligned with respective contacts (123) of said circuit board (12). . All metal connections between traces (121) of said circuit board (12) and contacts (101 ) of said circuit component (10) are further to pads (161) that join said rigid substrate (16 ). A circuit subassembly according to any one of claims 6 to 8, connected. The circuit subassembly of any one of claims 6 to 9, wherein said via (124) is formed from two or more layers including one layer of nickel and another layer of gold. A circuit subassembly according to any one of claims 6 to 10, wherein said flexible base (122) of said circuit board (12 ) is made from one or more plastic materials. A circuit subassembly according to any one of claims 6 to 11, wherein the rigid substrate (16) has a thickness of 250 µm or less, 200 µm or less, 150 µm or less, 100 µm or less, or 50 µm or less. A circuit subassembly according to any one of claims 6 to 12, wherein said rigid substrate (16) has a thickness of 5 µm or more, 10 µm or more, or 25 µm or more. A circuit subassembly according to any one of claims 6 to 13, wherein said rigid substrate (16) lacks conductive traces.