# US 2014/0152449 A1 · Early Detection of Environmental Conditions That Will Lead to Creep Corrosion on Printed Circuit Boards in Data Centers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152449 A1 - Document ID: US20140152449A1 - Status: Published application - Kind: A1 - Application number: 13/705,224 - Filed: 2012-12-05 - Published: 2014-06-05 - Earliest claimed: 2012-12-05 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Levente Klein; Prabjit Singh; Jing Zhang - Web page: https://patentgrep.com/patent/US20140152449A1 ## CPC - H05K 1/0268: {for electrical inspection or testing} - G01N 17/04: Corrosion probes - H05K 2201/0761: Insulation resistance, e.g. of the surface of the PCB between the conductors - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract Apparatus and method for directly detecting the atmospheric conditions leading to creep corrosion of printed circuit boards (PCBs) well before the PCBs in the computers start suffering from creep corrosion. The embodiment indicates the propensity of the air towards creep corrosion on PCBs. Additionally, to avoid the false reading due to condensed moisture, condensed moisture may be avoided by using a heater attached to the creep corrosion monitor that keeps the creep corrosion monitor above the dew point temperature. ## Claims ### Claim 1 1) An apparatus to monitor environmental conditions that may lead to creep corrosion, the apparatus comprising: a printed circuit board with inter-digitated comb patterns having spacing in between the patterns and a controlled level of organic acid flux contamination; a power supply and a high resistance resistor connected to the printed circuit board in series; a microprocessor connected across the high resistance resistor for monitoring changes in resistance of the circuit; and an alarm connected to the microprocessor wherein the alarm is activated when voltage in the circuit exceeds a threshold value. ### Claim 2 (depends on 1) 2) The apparatus of claim 1 wherein the inter-digitated comb patterns are made of a copper containing material. ### Claim 3 (depends on 1) 3) The apparatus of claim 1 wherein spacing between the patterns is about 0.25 mm. ### Claim 4 (depends on 1) 4) The apparatus of claim 1, wherein the alarm circuit indicates the creep corrosion propensity of the air. ### Claim 5 (depends on 1) 5) The system of claim 1 wherein the alarm circuit triggers an alarm when the test PCB short circuits which indicates that creep corrosion has occurred on the PCB. ### Claim 6 (depends on 1) 6) The apparatus of claim 1 further comprising a data logger connected to a non transitory storage medium for storing voltage versus time information, wherein the information includes the history of level of contaminants in the air that can cause creep corrosion. ### Claim 7 (depends on 1) 7) The apparatus of claim 1 wherein the flux contamination on the pattern is 10 to 100 microgram NaCl equivalent per cm square. ### Claim 8 (depends on 1) 8) The apparatus of claim 1 further comprising a sensor for monitoring relative humidity. ### Claim 9 (depends on 1) 9) The apparatus of claim 1 further comprising a heater connected to the creep corrosion monitor wherein the microprocessor controls the heater based on relative humidity and resistance of the circuit. ### Claim 10 (depends on 9) 10) The apparatus of claim 9 wherein the heater is connected to a separate power supply from the creep corrosion monitor. ### Claim 11 11) A method to monitor creep corrosion propensity of the air comprising: providing a printed circuit board with inter-digitated comb patterns having spacing in between the patterns, the circuit board connected to a microprocessor; connecting, in series, a power supply and a high resistance resistor to the printed circuit board connecting at least one of a data logger and an alarm circuit to the microprocessor to create a corrosion monitor; monitoring, by the microprocessor, the resistance of the circuit as voltage passes through the circuit; writing data to the data logger and triggering the alarm circuit in response to the voltage exceeding a threshold value. ### Claim 12 (depends on 1) 12) The method of claim 1 wherein the inter-digitated comb patterns are made of a copper containing material ### Claim 13 (depends on 1) 13) The method of claim 1 wherein the printed circuit board is attached to a heater, said heater controlled by the microprocessor. ### Claim 14 (depends on 13) 14) The method of claim 13 further comprising monitoring, by the microprocessor, the temperature of the printed circuit board. ### Claim 15 (depends on 14) 15) The method of claim 14 wherein a sensor is connected to the microprocessor to enable the microprocessor to calculate dew point. ### Claim 16 (depends on 15) 16) The method of claim 15 further comprising controlling the heater based on a comparison between the dew point and the temperature of the printed circuit board. ### Claim 17 (depends on 1) 17) The method of claim 1 further comprising triggering, by the circuit, an alarm when the test PCB short circuits indicating that creep corrosion has occurred on the PCB. ### Claim at position 18 (depends on 1) 18)The method of claim 1 further comprising storing, by a data logger, voltage versus time information, wherein the information includes the history of level of contaminants in the air that can cause creep corrosion. ### Claim 19 (depends on 1) 19) The method of claim 1 wherein the flux is an aggressive organic acid soldering no-clean flux.