Removing unwanted flux from an integrated circuit package

Patent metadata

Field	Value
Publication number	US-10512167-B2
Application number	US-201816135552-A
Country	US
Kind code	B2
Filing date	Sep 19, 2018
Priority date	Sep 19, 2017
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

A surface-mounted integrated circuit (IC) package is disclosed that has unwanted flux removed from surface-mounted IC. A bottom termination component (BTC) includes lands and a thermal pad. The lands provide an electrical connection from the BTC and the thermal pad provides heat transfer from the BTC. The thermal pad includes vias that are configured to remove flux generated from solder applied to the surface-mounted IC as the surface-mounted IC is assembled. A printed circuit board (PCB) is mounted to the BTC and is electrically connected to the BTC via the lands and receives heat transfer from the BTC via the thermal pad and includes a reservoir. The reservoir is configured to pull flux positioned between the lands into the reservoir as the flux is generated from the solder applied to the surface-mounted IC as the BTC is mounted to the PCB and as the surface-mounted IC is assembled.

First claim

What is claimed is:

1. A surface-mounted integrated circuit (IC) package, comprising: at least one bottom termination component (BTC) including a plurality of lands and a thermal pad, wherein the plurality of lands provides an electrical connection from the BTC and the thermal pad provides heat transfer from the BTC, and wherein the thermal pad includes a plurality of vias configured to remove flux generated from solder applied to the surface-mounted IC as the surface-mounted IC is assembled; and a printed circuit board (PCB) mounted to the BTC and electrically connected to the BTC via the plurality of lands, wherein the PCB receives the heat transfer from the BTC via the thermal pad and includes at least one reservoir, and wherein the at least one reservoir is configured to pull flux positioned between the plurality of lands into the at least one reservoir as the flux is generated from the solder applied to the surface-mounted IC as the BTC is mounted to the PCB and as the surface-mounted IC is assembled, wherein the plurality of vias are positioned in a staggered row and column formation so that each row of vias is not aligned with each immediate adjacent row of vias and each column of vias is not aligned with each immediate column of vias.

2. The surface-mounted IC package of claim 1 , wherein the plurality of vias extend from a first surface of the thermal pad through the thermal pad and to a second surface of the thermal pad opposite the first surface, and wherein the plurality of vias is mounted to the PCB and is further configured to:
purge flux from the first surface of the thermal pad and from between the plurality of lands generated from the solder applied to the surface-mounted IC; and
push the flux through the plurality of vias from the second surface of the thermal pad out onto a bottom surface of the PCB that is positioned opposite a top surface of the PCB to which the BTC is mounted so that that the flux is removed from between the thermal pad and the PCB and from between the plurality of lands.

3. The surface-mounted IC package of claim 2 , wherein the plurality of vias is further configured to:
prevent an excess volume of flux generated from the solder applied to the surface-mounted IC from purging through the plurality of vias;
maintain a solder bond with a thickness that is sufficient to attach the BTC to the PCB; and
maintain a spacing between the BTC and the PCB via the solder bond to allow flux to be flushed out from between the BTC and the PCB; and
wherein an optimal quantity of vias is included in the thermal pad with each via having an optimal diameter that enables an adequate amount of flux to be purged through the plurality of vias to remove the flux from the first surface of the thermal pad and from between the plurality of lands and prevents the excess volume of flux from being purged through the plurality of vias that reduces the spacing between the BTC and the PCB, thereby preventing the flux form being flushed out from between the BTC and the PCB.

4. The surface-mounted IC package of claim 1 , wherein the at least one reservoir is an opening in a solder mask applied to the surface-mounted IC package and is further configured to pull the flux positioned between the plurality of lands into the opening in the solder mask that is associated with the at least one reservoir as the flux transitions into a liquid.

5. The surface-mounted IC package of claim 1 , wherein the at least one reservoir is shaped as an elliptical pattern in the opening of the solder mask and is configured to pull the flux positioned between the plurality of lands into the elliptical pattern in the opening of the solder mask as the flux transforms into a spherical shape based on a capillary action of the flux as the flux transitions into the liquid.

6. The surface-mounted IC package of claim 5 , wherein a plurality of reservoirs is formed in the PCB with each reservoir shaped as the elliptical pattern and positioned between a ground land and a power land and configured to prevent current leakage between the ground land and the power land.

7. A surface-mounted integrated circuit (IC) package, comprising: at least one bottom termination component (BTC) that includes a thermal pad that provides heat transfer from the BTC, wherein the thermal pad includes a plurality of vias that is configured to remove flux generated from solder applied to the surface-mounted IC as the surface-mounted IC is assembled; a printed circuit board (PCB) that is mounted to the BTC and receives the heat transfer from the BTC via the thermal pad; and a plurality of lands with each land including a peripheral terminal that is electrically connected to a corresponding terminal from the plurality of terminals associated with the BTC and a trace that extends from the corresponding peripheral terminal and extends beyond a solder mask that is applied to the surface-mounted IC package, wherein each trace is connected to a corresponding peripheral terminal and is configured to prevent the BTC from tilting as the BTC is mounted to the PCB, wherein each of the peripheral terminals included in the plurality of lands have a substantially similar surface area and each of the traces that extend from the corresponding peripheral terminals have a substantially similar surface area.

8. The surface-mounted IC package of claim 7 , further comprising a plurality of solder deposits positioned between each land of the plurality of lands and each corresponding terminal from the plurality of terminals associated with the BTC, wherein each solder deposit includes a substantially equal volume of solder.

9. The surface-mounted IC package of claim 8 , wherein each of the solder deposits of substantially equal volume of solder is configured to conform to the substantially similar surface area of each corresponding peripheral terminal and the substantially similar surface area of each corresponding trace.

10. The surface-mounted IC package of claim 8 , wherein each of the solder deposits of substantially equal volume is further configured to mount the BTC to the PCB so that the BTC is substantially planar relative to the PCB based on the substantially equal volume of each solder deposit that conforms to the substantially similar surface area of each corresponding peripheral terminal and the substantially similar surface area of each corresponding trace.

11. The surface-mounted IC package of claim 8 , wherein each trace is added to each corresponding peripheral trace with each corresponding peripheral trace being non-solder mask defined.

12. A system for controlling an access control device via a controller incorporated into a surface-mounted integrated circuit (IC) package, comprising:
an access control device configured to execute an action to regulate access to a space;
at least one component associated with the access control device that is configured to detect data associated with activity involving access to the space; and
a controller that is configured to instruct the access control device to execute the action based on the data detected by the at least one component to regulate the space, the controller comprising:
at least one bottom termination component (BTC) that includes a plurality of lands and a thermal pad, wherein the plurality of lands provides an electrical connection from the BTC and the thermal pad provides heat transfer from the BTC, wherein the thermal pad includes a plurality of vias that is configured to remove flux generated from solder applied to the surface-mounted IC as the surface-mounted IC is assembled; and
a printed circuit board (PCB) that is mounted to the BTC and is electrically connected to the BTC via the plura

Assignees

• Schlage Lock Co Llc

Inventors

• Steiner Russell L

Classifications

• H05K3/3452

  Solder masks · CPC title

• H05K2201/10727

  Leadless chip carrier [LCC], e.g. chip-modules for cards · CPC title

• H05K2203/1178

  Means for venting or for letting gases escape · CPC title

• H05K2201/10969

  Metallic case or integral heatsink of component electrically connected to a pad on PCB · CPC title

• H05K3/303

  with surface mounted components (H05K3/32 takes precedence) · CPC title