# US 2017/0287732 A1 · Water soluble flux with modified viscosity > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0287732 A1 - Document ID: US20170287732A1 - Status: Published application - Kind: A1 - Application number: 15/089,208 - Filed: 2016-04-01 - Published: 2017-10-05 - Earliest claimed: 2016-04-01 - Assignees: Intel Corporation - Applicants: Intel Corporation - Inventors: Kabir J. Mirpuri - Web page: https://patentgrep.com/patent/US20170287732A1 ## CPC - H10W 70/097: {Cleaning} - B23K 35/3613: {Polymers, e.g. resins} - H05K 1/181: associated with surface mounted components - H10W 70/099: {Connecting interconnections to insulating or insulated package substrates, interposers or redistribution layers} - H10W 90/701: {characterised by the relative positions of pads or connectors relative to package parts} - B23K 2101/40: Semiconductor devices - B23K 2101/42: Printed circuits - H05K 1/11: Printed elements for providing electric connections to or between printed circuits - H05K 2201/10462: Flat component oriented parallel to the PCB surface - H05K 2201/10674: Flip chip - H10W 44/20: at high-frequency [HF] or radio frequency [RF] - H10W 72/01223: {in liquid form, e.g. by dispensing droplets or by screen printing} - H10W 72/01225: {in solid form, e.g. by using a powder or by stud bumping} - H10W 72/01257: {by reflowing} - H10W 72/019: {of bond pads} - H10W 72/20: Bump connectors, e.g. solder bumps or copper pillars; Dummy bumps; Thermal bumps - H10W 72/252: {comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu} - H10W 90/722: {between stacked chips} - H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL} - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract A one-step water soluble (WS) flux process may reduce residue staining and increase yields for bond grid array (BGA) packages. In one example, the WS flux may use increased amounts of bonding polymer (BP) and reduced amounts of amine to increase viscosity. The increased viscosity may eliminate using a second no-clean flux and enable a single WS flux to both clean the associated substrate and provide stable solder ball support during reflow. ## Claims ### Claim 1 A ball grid array (BGA) package, comprising: a substrate; a plurality of solder balls; and a water soluble (WS) flux on the substrate to promote connections between the substrate and the solder balls, wherein the WS flux includes around 5% -15% amine and 15% -20% bonding polymer. ### Claim 2 (depends on 1) The BGA of claim 1, wherein the substrate includes bond pads and the WS flux extends over the bond pads and supports the solder balls during reflow. ### Claim 3 (depends on 2) The BGA of claim 2, wherein the WS flux is to clean the bond pads on an ajinomoto buildup film (ABF) layer. ### Claim 4 (depends on 3) The BGA of claim 3, wherein the WS flux is the only flux applied to the bond pads. ### Claim 5 (depends on 1) The BGA of claim 1, wherein the WS flux includes around 55-75% solvent and a remaining portion that includes acid. ### Claim 6 (depends on 1) The BGA of claim 1, wherein the WS flux includes around 10% amine and around 17% bonding polymer. ### Claim 7 (depends on 1) The BGA of claim 1, wherein the WS flux is loaded with around 20% or more solder particles. ### Claim 8 (depends on 1) The BGA of claim 1, wherein the WS flux is non-rosin based. ### Claim 9 A method comprising: applying a water soluble (WS) flux to a bond pad, wherein an amount of bonding polymer (BP) in the WS flux is greater than an amount of amine in the WS flux; placing a solder ball on the WS flux; and reflowing the WS flux and the solder ball to form a connection between the bond pad and the solder ball. ### Claim 10 (depends on 9) The method of claim 9, including using the WS flux to clean the bond pad on an ajinomoto buildup film (ABF) layer and to retain the solder ball during reflow to form the connection. ### Claim 11 (depends on 9) The method of claim 9, wherein the WS flux includes a ratio of amine to BP of between 0.25 and 0.9. ### Claim 12 (depends on 9) The method of claim 9, wherein the WS flux includes around 17% BP and around 10% amine. ### Claim 13 (depends on 9) The method of claim 9, wherein the WS flux is loaded with around 20% or more solder particles. ### Claim 14 (depends on 9) The method of claim 9, further comprising applying only the WS flux to the bond pad in a one-step flux operation prior to reflowing the WS flux and the solder ball to form the connection. ### Claim 15 A water soluble (WS) flux, comprising: base materials; 5-15% amine; and 15-20% bonding polymer. ### Claim 16 (depends on 15) The WS flux of claim 15, wherein the base materials, amine and bonding polymer have a viscosity of around 30-100 pascal-second (Pa.s). ### Claim 17 (depends on 15) The WS flux of claim 15 wherein the base materials include a solvent and acid. ### Claim 18 (depends on 17) The WS flux of claim 17, including around 10% amine, 17% base polymer, and 55-75% solvent. ### Claim 19 (depends on 15) The WS flux of claim 15, wherein the base materials are non-rosin based. ### Claim 20 (depends on 18) The WS flux of claim 18, including around 20% or more solder particles and a combination of the acid, amine, solvent and bonding polymer are reduced by around 20% or more.