# US 9,521,752 B2 · Method of making an electronic device having a thin film resistor formed on an LCP solder mask and related devices

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- Number: US 9,521,752 B2
- Document ID: US9521752B2
- Status: Granted
- Kind: B2
- Application number: 14/490,866
- Filed: 2014-09-19
- Published: 2016-03-24
- Granted: 2016-12-13
- Earliest claimed: 2014-09-19
- Assignees: Harris Corporation
- Applicants: Harris Corporation
- Inventors: Louis Joseph Rendek, Jr.
- Web page: https://patentgrep.com/patent/US9521752B2

## CPC

- H05K 3/3452: Solder masks
- H05K 1/028: {Bending or folding regions of flexible printed circuits (H05K1/0283 takes precedence)}
- H05K 1/03: Use of materials for the substrate
- H05K 1/111: {Pads for surface mounting, e.g. lay-out}
- H05K 1/115: {Via connections; Lands around holes or via connections (H05K1/112 takes precedence)}
- H05K 1/167: {incorporating printed resistors}
- H05K 3/16: by cathodic sputtering
- H05K 3/3436: {having an array of bottom contacts, e.g. pad grid array or ball grid array components}
- H05K 3/4038: {Through-connections; Vertical interconnect access [VIA] connections (H05K3/403, H05K3/42 take precedence)}
- H05K 1/0393: {Flexible materials (H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups)}
- H05K 2201/0141: Liquid crystal polymer [LCP]
- H05K 2201/05: Flexible printed circuits [FPCs]
- H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL}
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method of making an electronic device may include forming at least one circuit layer that includes solder pads on a substrate and forming at least one liquid crystal polymer (LCP) solder mask having mask openings therein. The method may also include forming at least one thin film resistor on the LCP solder mask and coupling the at least one LCP solder mask to the substrate so that the at least one thin film resistor is coupled to the at least one circuit layer and so that the solder pads are aligned with the mask openings.

## Claims

### Claim 1

A method of making an electronic device comprising:
forming at least one circuit layer comprising a plurality of solder pads on a substrate having opposing first and second major surfaces;
forming a plurality of liquid crystal polymer (LCP) solder masks each carried by a respective one of the first and second major surfaces of the substrate and each having opposing first and second major surfaces and a plurality of mask openings therein extending between the first and second major surfaces thereof;
forming at least one thin film resistor directly on the first major surface of at least one of the plurality of LCP solder masks; and
coupling the plurality of LCP solder masks to the substrate so that the at least one thin film resistor is coupled to the at least one circuit layer and so that the plurality of solder pads is aligned with the plurality of mask openings.

### Claim 2 (depends on 1)

The method of claim 1 wherein at least one of the plurality of LCP solder masks is coupled to the substrate so that the at least one thin film resistor is sandwiched between the at least one of the plurality of LCP solder masks and the substrate.

### Claim 3 (depends on 1)

The method of claim 1 wherein forming the at least one thin film resistor comprises forming at least one thin film resistor on each of the plurality of LCP solder masks.

### Claim 4 (depends on 3)

The method of claim 3 wherein each LCP solder mask is coupled to the respective one of the first and second major surfaces of the substrate so that the plurality of thin film resistors are sandwiched between the plurality of LCP solder masks and the substrate.

### Claim 5 (depends on 1)

The method of claim 1 wherein the at least one thin film resistor is formed on the at least one LCP solder mask by sputtering.

### Claim 6 (depends on 1)

The method of claim 1 further comprising attaching a circuit component to corresponding solder pads of the plurality thereof.

### Claim 7 (depends on 1)

The method of claim 1 further comprising forming at least one electrically conductive via through the substrate.

### Claim 8 (depends on 1)

The method of claim 1 wherein the substrate comprises an LCP substrate.

### Claim 9 (depends on 1)

The method of claim 1 wherein the substrate comprises a flexible printed circuit board (PCB).