Automated process monitoring

Instrumentation for automated process monitoring of the amount of material in a liquid solution, comprising:

• a solution loading analyzer including a measurement well for containing a sample of solution to be analyzed, probe means positioned inside said measurement well and including light source means for generating light radiation and first and second photodetector means for receiving, respectively, light transmitted through said sample and incident light from said light source means, a computation means connected to receive signals respectively from said first and second photodetector means for computing the negative logarithm of the ratio of said signals and generating an output signal;
• flow pathway means connected to said solution loading analyzer for transporting said sample to and from said measurement well;
• cleaning means connected to said solution loading analyzer having a spray nozzle positioned inside said measurement well for cleaning said probe means between samples;
• and
• a programmable logic controller connected to said solution loading analyzer, said flow pathway means, and said cleaning means for controlling flow in said flow pathway means, for controlling measurement by said probe means, and for controlling cleaning by said cleaning means, said programmable logic controller providing timed directions to transport said sample to said measurement well in said solution loading analyzer through said flow pathway means, to permit said sample to de-aerate in said measurement well, to measure said sample for solution loading with said probe means, to transport said sample away from said measurement well, and to clean said probe means by spraying cleaning fluid on said probe means through said spray nozzle.

Instrumentation for the automated process monitoring of an imager and a developer bath in a printed circuit printer, comprising:

• operating and reference ultraviolet sensors positioned in an imager for exposing photoresist film layered on a substrate, said operating sensor being continuously exposed to ultraviolet radiation from an ultraviolet lamp in said imager, said reference ultraviolet sensor being protected from continuous exposure by a solenoid actuated shutter;
• a developer bath for developing exposed photoresist film on a substrate connected to a solution loading analyzer by a flow pathway means, said solution loading analyzer being supplied samples of developer solution via said flow pathway means;
• said solution loading analyzer including a measurement well for containing a sample of said developer solution, probe means positioned inside said measurement well and including light source means for generating light radiation and first and second photodetector means for receiving, respectively, light transmitted through said sample and incident light from said light source means, a computation means connected to receive signals respectively from said first and second photodetector means for computing the negative logarithm of the ratio of said signals and generating an output signal;
• and
• a programmable logic controller electrically connected to receive signals proportional to ultraviolet radiation sensed by said operating and reference ultraviolet sensors, to said solenoid actuated shutter, and to said solution loading analyzer for monitoring the solarization of said operating sensor and the loading of said developer bath, said programmable logic controller being programmed to test the solarization of said operating sensor by directing said solenoid actuated shutter to open at a predetermined time and expose said operating and reference sensors to the same intensity ultraviolet radiation and comparing the signals proportional to the ultraviolet radiation sensed by said operating and reference sensors, said programmable logic controller being programmed to determine loading of said developer bath by monitoring said output signal from said computation means of said solution loading analyzer.