A method for evaluating the quality of sintering furnace

Abstract

The present invention provides a method for evaluating the quality of resistor products after sintering in a sintering furnace, comprising the following steps: 1. setting samples to be sintered made from the same raw materials as standard samples; 2. introducing the standard samples into the sintering furnace in batches; 3. using the same resistance measurement system to measure the resistance values of different batches of standard samples after sintering, and calculating the average value difference and CPK value of a specified column; 4. using the same thickness measurement system to measure the thickness difference between different batches of standard samples before and after sintering, and calculating the thickness shrinkage rate at a specified location; 5. determining the sintering quality of the sintering furnace based on the calculation results. The present invention has the advantages of being able to conveniently, quickly, and accurately evaluate the quality of a sintering furnace. Based on the evaluation results, maintenance can be performed on equipment anomalies or the product grade that the equipment can produce can be calibrated.

Description

Technical Field

[0001] The invention relates to an equipment evaluation method, in particular to a method for evaluating the quality of a sintering furnace. Background Art

[0002] Chip resistor production requires a tunnel-type sintering furnace to sinter the resistor ink at high temperatures. However, parameters within each zone within the furnace (such as temperature, airflow, and atmosphere) vary both spatially and temporally. This results in inconsistent material properties after sintering for products placed at different times and positioned in different locations. Furthermore, the performance of each sintering furnace varies, leading to variations in the properties of products produced from different furnaces. This results in a wide dispersion of characteristic values for products of the same specification, resulting in a high defect rate. Currently, there is no effective method or means to objectively and accurately evaluate sintering furnace performance.

[0003] Therefore, it is necessary to provide a new technical solution. Summary of the Invention

[0004] In order to solve the technical problems existing in the prior art, the present invention discloses a method for evaluating the quality of a sintering furnace. The specific technical solution is as follows:

[0005] The present invention provides a method for evaluating the quality of a sintering furnace, comprising the following steps:

[0006] S1. Prepare a standard sample. The standard sample is a sample with a resistive film layer to be sintered using the same raw materials and produced at the same time and on the same equipment.

[0007] S2. After the resistor film layer of the standard samples is screen-printed and dried in a drying oven, the standard samples are divided into three columns (left, middle, and right) and placed on the chain of the sintering furnace. Each row of standard samples is added at a time, and a row of standard samples is fed into the sintering furnace at regular intervals.

[0008] S3. After sintering is completed, the resistance value of the resistor pattern at the same position in the specified standard sample is measured under the same resistance measurement system and the data is recorded;

[0009] S4. Calculate the average resistance difference and CPK value difference between the standard samples sintered at the left, middle, and right positions of the sintering furnace at the same time;

[0010] S5. Calculate the average resistance value difference and CPK value difference between the standard samples sintered at the same sintering position at different times;

[0011] S6. Using the same thickness measurement system, test the thickness difference of standard samples from different batches before and after sintering, and calculate the thickness shrinkage at the specified location;

[0012] S7. Evaluate the difference in sintering quality caused by different positions at the same time based on the calculation results of S4. Evaluate the difference in sintering quality caused by different times at the same position based on the calculation results of S5. Finally, make a comprehensive judgment on the overall sintering quality of the sintering furnace.

[0013] Furthermore, the standard sample is prepared by selecting a screen, substrate and slurry used in mass production to produce a standard sample of the resistor film layer to be sintered.

[0014] Furthermore, resistor patterns of multiple sizes are respectively arranged at the four corners and the middle position of the standard sample, and at least five resistor patterns of each size are arranged at the five positions.

[0015] Furthermore, in S2, the standard sample is put into the sintering furnace once every four hours for at least fourteen consecutive days.

[0016] Furthermore, in S3, three standard samples are randomly selected from each left, middle, and right column of each row of standard samples, and then the resistance values of five same-sized patterns are collected from the resistance patterns at the four corners and the middle of each standard sample, and the average resistance value of the same-sized patterns in each column of each row of standard samples is calculated.

[0017] Furthermore, according to S4 and S5, the difference in the average value of the resistance values at different positions at the same time and the difference in the average value of the resistance values at the same position at different times are calculated respectively, and a judgment result is obtained based on the difference in the average value:

[0018] When the difference in the average value is greater than 10%, resistor production cannot be carried out and the machine must be shut down for maintenance;

[0019] When the difference in the average value is less than or equal to 10%, only resistance values below 1K ohm can be produced, which needs to be improved;

[0020] When the difference in the average value is less than or equal to 5%, all resistance values can be produced and improvement is recommended;

[0021] When the difference in the average value is less than or equal to 2%, the equipment is excellent and can produce all resistance value segments.

[0022] Furthermore, the CPK value is calculated as: CPK = min{(upper specification limit - mean value) / 3 / standard deviation, (mean value - lower specification limit) / 3 / standard deviation}. The judgment result is obtained based on the CPK value:

[0023] When CPK>1.33, it can be used as a high value-added product;

[0024] When 1.2≤CPK<1.33, the equipment is excellent and can produce all resistance ranges;

[0025] When 1.1≤CPK<1.2, the equipment is in good condition and can produce all resistance ranges;

[0026] When 1≤CPK<1.1, the equipment is qualified and improvement is recommended;

[0027] When CPK<1, the equipment is unqualified and cannot be produced.

[0028] The present invention has the following beneficial effects: the present invention evaluates the sintering quality inside the sintering furnace by measuring the resistance values at different times and spaces in the sintering furnace, and can conveniently, quickly and accurately evaluate the quality of the sintering furnace. According to the evaluation results, equipment abnormalities can be maintained or the product grade that the equipment can produce can be calibrated.

[0029] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. DETAILED DESCRIPTION

[0030] To further illustrate the technical solutions and technical effects adopted by the present invention, detailed description is given below in conjunction with embodiments.

[0031] The present invention discloses a method for evaluating the quality of a sintering furnace, comprising the following steps:

[0032] S1. Prepare a standard sample. The standard sample is a sample with a resistive film layer to be sintered using the same raw materials and produced at the same time and on the same equipment.

[0033] S2. After the resistor film layer of the standard samples is screen-printed and dried in a drying oven, the standard samples are divided into three columns (left, middle, and right) and placed on the chain of the sintering furnace. Each row of standard samples is added at a time, and a row of standard samples is fed into the sintering furnace at regular intervals.

[0034] S3. After sintering is completed, the resistance value of the resistor pattern at the same position in the specified standard sample is measured under the same resistance measurement system and the data is recorded;

[0035] S4. Calculate the average resistance difference and CPK value difference between the standard samples sintered at the left, middle, and right positions of the sintering furnace at the same time;

[0036] S5. Calculate the average resistance value difference and CPK value difference between the standard samples sintered at the same sintering position at different times;

[0037] S6. Using the same thickness measurement system, test the thickness difference of standard samples from different batches before and after sintering, and calculate the thickness shrinkage at the specified location;

[0038] S7. Evaluate the difference in sintering quality caused by different positions at the same time based on the calculation results of S4. Evaluate the difference in sintering quality caused by different times at the same position based on the calculation results of S5. Finally, make a comprehensive judgment on the overall sintering quality of the sintering furnace.

[0039] The standard sample is prepared using mass-produced screens, substrates, and slurries to create a standard sample of the resistor film layer to be sintered. In one embodiment, the four corners and center of the standard sample are each provided with resistor patterns of various sizes, with at least five resistor patterns of each size at each of the five locations. In S2, the standard sample is placed in the sintering furnace every four hours for at least fourteen consecutive days.

[0040] In S3, three standard samples are randomly selected from each left, middle, and right column of each row of standard samples. Then, the resistance values of five same-sized patterns are collected from the resistance patterns at the four corners and the middle of each standard sample, and the average resistance value of the same-sized patterns in each column of each row of standard samples is calculated.

[0041] In one embodiment, the difference in average values of resistance values at different locations at the same time and the difference in average values of resistance values at the same location at different times are calculated according to S4 and S5, and a judgment result is obtained based on the difference in average values:

[0042] When the difference in the average value is greater than 10%, resistor production cannot be carried out and the machine must be shut down for maintenance;

[0043] When the difference in the average value is less than or equal to 10%, only resistance values below 1K ohm can be produced, which needs to be improved;

[0044] When the difference in the average value is less than or equal to 5%, all resistance values can be produced and improvement is recommended;

[0045] When the difference in the average value is less than or equal to 2%, the equipment is excellent and can produce all resistance ranges.

[0046] The CPK value is calculated as follows: CPK = min{(upper specification limit - average value) / 3 / standard deviation, (average value - lower specification limit) / 3 / standard deviation}. The judgment result is obtained based on the CPK value:

[0047] When CPK>1.33, it can be used as a high value-added product;

[0048] When 1.2≤CPK<1.33, the equipment is excellent and can produce all resistance ranges;

[0049] When 1.1≤CPK<1.2, the equipment is in good condition and can produce all resistance ranges;

[0050] When 1≤CPK<1.1, the equipment is qualified and improvement is recommended;

[0051] When CPK<1, the equipment is unqualified and cannot be produced.

[0052] Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention, and that those skilled in the art may make changes, modifications and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for evaluating the quality of a sintering furnace, characterized in that: The steps include: S1. Prepare a standard sample, which is a sample with a resistive film layer to be sintered using the same raw materials and produced at the same time and on the same equipment; S2. After the resistor film layer of the standard samples is screen-printed and dried in a drying oven, the standard samples are divided into three columns (left, middle, and right) and placed on the chain of the sintering furnace. Each row of standard samples is added at a time, and a row of standard samples is fed into the sintering furnace at regular intervals. After S3 sintering is completed, the resistance value of the resistor pattern at the same position in the specified standard sample is measured under the same resistance measurement system and the data is recorded; S4. Calculate the average resistance difference and CPK value difference between the standard samples sintered at the left, middle, and right positions of the sintering furnace at the same time; S5. Calculate the average resistance value difference and CPK value difference between the standard samples sintered at the same sintering position at different times; S6. Using the same thickness measurement system, test the thickness difference of standard samples from different batches before and after sintering, and calculate the thickness shrinkage at the specified location; S7. Evaluate the difference in sintering quality caused by different positions at the same time based on the calculation results of S4. Evaluate the difference in sintering quality caused by different times at the same position based on the calculation results of S5. Finally, make a comprehensive judgment on the overall sintering quality of the sintering furnace. According to S4 and S5, the difference in the average value of the resistance values at different positions at the same time and the difference in the average value of the resistance values at the same position at different times are calculated respectively, and the judgment result is obtained based on the difference in the average value: When the difference in the average value is greater than 10%, resistor production cannot be carried out and the machine must be shut down for maintenance; When the difference in the average value is less than or equal to 10%, only resistance values below 1000 ohms can be produced, which requires improvement; When the difference in the average value is less than or equal to 5%, all resistance values can be produced and improvement is recommended; When the difference in the average value is less than or equal to 2%, the equipment is excellent and can produce all resistance ranges. The CPK value is calculated as follows: CPK = min{(upper specification limit - average value) / 3 / standard deviation, (average value - lower specification limit) / 3 / standard deviation}. The judgment result is obtained based on the CPK value: When CPK>1.33, it can be used as a high value-added product; When 1.2≤CPK<1.33, the equipment is excellent and can produce all resistance ranges; When 1.1≤CPK<1.2, the equipment is in good condition and can produce all resistance ranges; When 1≤CPK<1.1, the equipment is qualified and improvement is recommended; When CPK<1, the equipment is unqualified and cannot be produced.

2. The method for evaluating the quality of a sintering furnace according to claim 1, wherein: The standard sample is prepared by selecting the screen, substrate and slurry used in mass production to prepare the standard sample of the resistor film layer to be sintered.

3. The method for evaluating the quality of a sintering furnace according to claim 2, characterized in that: Resistor patterns of various sizes are respectively arranged at the four corners and the middle of the standard sample, and at least five resistor patterns of each size are arranged at the five positions.

4. The method for evaluating the quality of a sintering furnace according to claim 1, wherein: In S2, the standard sample is put into the sintering furnace once every four hours for at least fourteen consecutive days.

5. The method for evaluating the quality of a sintering furnace according to claim 1, wherein: In S3, three standard samples are randomly selected from each left, middle, and right column of each row of standard samples. Then, the resistance values of five same-sized patterns are collected from the resistance patterns at the four corners and the middle of each standard sample, and the average resistance value of the same-sized patterns in each column of each row of standard samples is calculated.