Apparatus for setting heating condition in heating furnace and thermal analyzer for object to be heated in heating furnace

An apparatus for setting heating conditions in a heating furnace, comprising:

• setting means for setting heating conditions to a plurality of heating sources respectively when heating an object to be heated by means of the heating sources in the heating furnace;
• detecting means for detecting a temperature of the heated object at a plurality of detection points;
• computing means for computing, for each heating source, a relationship between a variation in the heating conditions in one of the heating sources and a variation in a detected temperature at each of the detection points of the object;
• calculating means for calculating heating conditions in the heating source for causing the detection point of the object to have a target temperature based on the computed relationship;
• and
• control means for controlling the heating sources on the calculated heating conditions,
• wherein the heating furnace is formed of a reflow furnace, the object is formed of a printed-wiring board having electronic components mounted thereon, the heating sources are formed of two or more electric heating sources of hot air blasting and heat radiation types, and the printed-wiring board is heated by simultaneously using the two or more electric heating sources of the different types.

A computer readable recording medium which records a heating condition setting program in a heating furnace, causing a computer to execute the steps of:

• setting heating conditions to a plurality of heating sources respectively when heating an object to be heated by means of the heating sources in the heating furnace;
• detecting a temperature of the heated object at a plurality of detection points;
• computing, for each heating source, a relationship between a variation in the heating conditions in one of the heating sources and a variation in a detected temperature at each of the detection points of the object;
• calculating heating conditions in the heating source for causing the detection point of the object to have a target temperature based on the computed relationship;
• and
• controlling the heating sources on the calculated heating conditions.

A thermal analyzer for an object to be heated in a heating furnace, comprising:

• object data input means for inputting a shape and a physical property value of the object moving in the heating furnace at a predetermined speed;
• computation grid generating means for dividing the object in a grid shape to generate a computation grid and for defining a physical property value for each computation element divided by the computation grid;
• heating condition input means for inputting heating conditions in the heating furnace;
• setting means for setting, on the input heating conditions, a radiation boundary condition and a convection boundary condition of the object which are changed with a passage of time;
• calculating means for calculating a temperature distribution for each computation element every movement of the object within a predetermined range based on the radiation boundary condition and the convection boundary condition which are set by the setting means and heat conduction in the object for each computation element generated by the computation grid generating means;
• and
• output means for outputting the temperature distribution calculated by the calculating means.

A computer readable recording medium which records a thermal analysis program of an object to be heated in a heating furnace, causing a computer to execute the steps of:

• inputting a shape and a physical property value of the object moving in the heating furnace at a predetermined speed;
• dividing the object in a grid shape to generate a computation grid and for defining a physical property value for each computation element divided by the computation grid;
• inputting heating conditions in the heating furnace;
• setting, on the input heating conditions, a radiation boundary condition and a convection boundary condition of the object which are changed with a passage of time;
• calculating a temperature distribution for each computation element every movement of the object within a predetermined range based on the set radiation boundary condition and convection boundary condition and heat conduction in the object for each generated computation element;
• and
• outputting the calculated temperature distribution.

A controller for a reflow furnace comprising a thermal analyzer which performs thermal analysis for a printed-wiring board moving in the reflow furnace, and a heating condition setting apparatus for setting heating conditions in the reflow furnace based on a result of the thermal analysis obtained by the thermal analyzer,

• the thermal analyzer including:
• shape and physical property value input means for inputting a shape of a printed-wiring board to be heated in the reflow furnace and a physical property value thereof, a shape of a component mounted on the printed-wiring board and a physical property value thereof, a shape of a gap space between the component and the printed-wiring board, and a shape of a terminal space having a terminal for connecting the component and the printed-wiring board and a physical property value of the terminal;
• component and gap space model setting means for setting a model in which the input component and gap space is regarded as a rectangular prism having a thickness that is almost equal to a thickness of the printed-wiring board;
• terminal model setting means for setting a model in which the input terminal space is regarded as a rectangular prism having a thickness corresponding to a size of the terminal;
• correcting means for correcting physical property values for the rectangular prism models of the component, the gap space and the terminal space which are thus obtained;
• computation grid generating means for dividing the rectangular prism model in a grid shape to generate a computation grid and for defining a physical property value for each computation element divided by the computation grid;
• heating condition input means for inputting heating conditions in the heating furnace;
• setting means for setting, on the input heating conditions, a radiation boundary condition and a convection boundary condition of the object which are changed with a passage of time;
• calculating means for calculating a temperature distribution for each computation element every movement of the object within a predetermined range based on the radiation boundary condition and the convection boundary condition which are set by the setting means and heat conduction in the object for each computation element generated by the computation grid generating means;
• and
• output means for outputting the temperature distribution calculated by the calculating means, and
• the heating condition setting apparatus including:
• heating condition setting means for setting heating conditions to a plurality of heating sources respectively when heating the object by means of the heating sources in the heating furnace;
• temperature detecting means for receiving, from the thermal analyzer, a temperature distribution for each computation element of the heated rectangular prism model;
• computing means for computing, for each heating source, a relationship between a variation in the heating conditions in one of the heating sources and a variation in a temperature of each computation element of the rectangular prism model;
• heating condition calculating means for calculating heating conditions in the heating source for causing the computation element of the rectangular prism model to have a target temperature based on the computed relationship;
• and
• control means for controlling the heating sources on the calculated heating conditions.

A computer readable recording medium which records a control program of a reflow furnace to cause a computer to execute steps of:

• performing thermal analysis for a printed-wiring board moving in the reflow furnace;
• and
• setting heating conditions of the reflow furnace based on a result of the thermal analysis obtained at the thermal analyzing step,
• the thermal analyzing step including steps of:
• inputting a shape of the printed-wiring board to be heated in the reflow furnace and a physical property value thereof, a shape of a component mounted on the printed-wiring board and a physical property value thereof, a shape of a gap space between the component and the printed-wiring board, and a shape of a terminal space having a terminal for connecting the component and the printed-wiring board and a physical property value of the terminal;
• setting a model in which the input component and gap space is regarded as a rectangular prism having a thickness that is almost equal to a thickness of the printed-wiring board;
• setting a model in which the input terminal space is regarded as a rectangular prism having a thickness corresponding to a size of the terminal;
• correcting physical property values for the rectangular prism models of the component, the gap space and the terminal space which are thus obtained;
• dividing the rectangular prism model in a grid shape to generate a computation grid and defining a physical property value for each computation element divided by the computation grid;
• inputting heating conditions in the heating furnace;
• setting, on the input heating conditions, a radiation boundary condition and a convection boundary condition of the object which are changed with a passage of time;
• calculating a temperature distribution for each computation element every movement of the object within a predetermined range based on the set radiation boundary condition and convection boundary condition and heat conduction in the object for each generated computation element;
• and
• outputting the calculated temperature distribution, and
• the heating condition setting step including steps of:
• setting heating conditions to a plurality of heating sources respectively when heating the object by means of the heating sources in the heating furnace;
• receiving, from the thermal analyzer, a temperature distribution for each computation element of the heated rectangular prism model;
• computing, for each heating source, a relationship between a variation in the heating conditions in one of the heating sources and a variation in a temperature of each computation element of the rectangular prism model;
• calculating heating conditions in the heating source for causing the computation element of the rectangular prism model to have a target temperature based on the computed relationship;
• and
• controlling the heating sources on the calculated heating conditions.