JP2011210884A - Quality control method of solder junction and quality control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the quality control method of a solder junction which can a perform non-destructive and highly accurate quality inspection on real time without additional inspections.SOLUTION: The quality control method of a junction formed by supplying (S0) solder and local thermal energy on a resin substrate includes a process (S1) to measure the time variation of temperature of the junction during junctioning, a process (S2) to find a plurality of feature quantities from measured data, a process (S3) to find a single numerical value index from the plurality of feature quantities, and a process (S4) to determine whether the junction is suitable (S5) or not suitable (S6) comparing the numerical value index and a predetermined threshold value (S4). The plurality of feature quantities includes a time tin which the temperature of the junction is a predetermined temperature Tor more to satisfy a condition (the glass transition temperature of the substrate-50°C)≤T≤(the glass transition temperature of the substrate+250°C) and a time tin which the temperature of the junction reaches a predetermined temperature Tto satisfy a condition (the glass transition temperature of the substrate-50°C)≤T≤(the glass transition temperature of the substrate+250°C) from the start time of heating by the thermal energy.

Description

  The present invention relates to a technique for quality control of a solder joint portion between a resin substrate terminal and an electronic component terminal.

  Soldering is a technique for joining electronic component terminals to terminals of printed circuit boards and build-up boards (hereinafter collectively referred to as resin boards) composed of a resin base material such as epoxy resin and metal wiring such as copper. Widely used. In general, a reflow method is widely used in which a solder paste is screen-printed on the terminals of a resin substrate, the electrodes of electronic components are positioned and mounted, and then the entire substrate is heated and soldered in a furnace. .

  However, since the reflow method heats the entire substrate, the mounted electronic components are also exposed to the same thermal load. For this reason, package parts including elements having low heat resistance (for example, light emitting diodes, resin molded parts, etc.) cannot be processed in a furnace having a high temperature equal to or higher than the upper limit of the heat resistance temperature. Such low heat-resistant components are a method for realizing electrical bonding by locally supplying heat and solder to the joint between the board terminal and the component terminal so that the package temperature does not rise to the upper limit of the heat resistance temperature , Referred to as a local heating mounting method).

  As a representative example of such a local heating mounting method, a soldering iron method is widely used in which a thread solder and a high-temperature iron are supplied to and joined to the joint portion. There is a problem in the existence of variations in work, and it is not suitable for soldering parts with multiple pins, narrow pitch, and mass production.

  As a local heating mounting method suitable for such a production form, instead of supplying heat energy with a high-temperature iron, a method of supplying heat energy to a joint by a beam precisely positioned by a control device is known. Yes. A semiconductor laser is often used as the beam, but it is not limited to this (hereinafter, representatively referred to as a laser solder method) (for example, see Non-Patent Document 1).

  With the laser solder method, heat energy can be supplied to extremely small joints (generally with a spot diameter of 1mm or less) in a short time (generally within 1 second) with high positional accuracy, making automation and high speed easy and multi-pin. Suitable for soldering of small pitch, mass production parts.

  In addition to the method of supplying thread solder and thermal energy at the same time, the laser solder method is also advantageous in the method of forming preliminary solder on the component electrode and / or the substrate electrode in advance.

Kisaku Murakami: Semiconductor laser soldering equipment, Optical Alliance, March 2003, p.32-36

  However, in the laser solder method, the inventors of the present application tend to vary the characteristics of a short-term transient temperature-time change (hereinafter simply referred to as temperature characteristics) at the joint, which greatly affects the joint quality. I found out. This is in addition to the fact that a substance (solder) and thermal energy (laser beam) are supplied, and that multiple phenomena such as melting, wetting and solidification of the solder occur simultaneously and continuously in a short time. , Solder supply speed, pre-solder amount and laser power variation, wettability variation due to differences in electrode surface condition, joint heat capacity (electrode thickness, pre-solder amount, substrate thickness, etc.) On the other hand, the temperature characteristics change sensitively.

  Such a phenomenon does not occur in resistance welding that gives only heat energy, welding or brazing with a long joining time, and is unique to the local heating mounting method. The bonding quality here is generally (1) the solder is transferred to the bonding portion by an appropriate amount, spreads and spreads to form a fillet, and a good metal bonding interface is formed. In many cases, it can be secured.

  However, (2) it is also required that thermal degradation does not occur at the interface between the metal under the terminal of the resin substrate and the resin base material due to excessive heat input at the joint. Although the deterioration of the resin at the interface does not reveal a defect at the beginning of product shipment, it may cause the interface to peel off due to heat shock or moisture absorption in the market, and may cause disconnection of the metal wiring.

  In the thermal degradation state of the interface between the metal of the substrate and the resin base material as in (2) above, it is difficult to discriminate by an electrical test or an appearance test because electrical continuity is obtained at the time of product shipment. Further, since the interface is not completely separated, there is a problem that it is difficult to apply a method for discriminating based on a difference in thermal conductivity of the interface as disclosed in Japanese Patent Application Laid-Open No. 2000-261137. .

  Note that the problem in bonding quality described in (2) above is related to mounting on a low heat-resistant resin substrate, and this problem does not occur in resistance welding, welding, or brazing, which are mainly bonding between metals. It is unique to the local heating mounting method applied to the resin substrate.

  Furthermore, the technique disclosed in Japanese Patent Application Laid-Open No. 2000-261137 has a problem that an additional process is required in addition to the soldering process, leading to a long lead time. In addition, when non-conformities are detected in the subsequent inspection process, the previous soldering process, the cause investigation for the previous process, and the timing of process correction are delayed, creating many defective products. There was a problem. Furthermore, since additional thermal energy is given in the inspection process, there is a problem that thermal deterioration of the interface between the metal of the substrate and the resin base material is promoted.

  This invention is made in view of the above, Comprising: In solder joining technology which supplies both a solder and a thermal energy to a junction part, the thermal deterioration of the interface of the metal of a board | substrate and a resin base material is included. It is an object of the present invention to obtain a solder joint quality control method and a quality control device that can inspect non-destructively and accurately in real time without additional inspection steps.

In order to solve the above-described problems and achieve the object, the present invention is a quality control method of a solder joint formed by supplying solder and local thermal energy on a resin substrate, Measuring data of temporal changes in temperature of the joint, obtaining a plurality of feature amounts from the measured data, obtaining a single numerical index from the plurality of characteristic amounts, and the numerical index Comparing with a predetermined threshold value to determine whether the joint is conforming or non-conforming, and a plurality of the feature amounts are determined by a temperature of the joint (glass transition temperature of the substrate −50 ° C.) ≦ T ₁ ≦ (Glass transition temperature of the substrate + 250 ° C.) The time t ₁ when the temperature T ₁ is equal to or higher than the predetermined temperature T ₁ and the temperature at the joint is the heating start point by the thermal energy From And a time t ₂ until reaching a predetermined T ₂ that satisfies a condition of (glass transition temperature of the substrate −50 ° C.) ≦ T ₂ ≦ (glass transition temperature of the substrate + 250 ° C.). .

  Advantageous Effects of Invention According to the present invention, it is possible to provide a solder joint quality control method and a quality control device capable of inspecting joint quality including interface deterioration in solder joints in a non-destructive and accurate manner in real time without an additional inspection process. Play.

FIG. 1 is a diagram showing a state during joining in laser soldering according to the first embodiment of the present invention. FIG. 2 is a diagram for explaining an example of a profile of laser power and solder supply speed, which are joining conditions in the first embodiment. FIG. 3 is a diagram showing a result of measuring a time change state of the temperature of the joint portion which is a conforming product in the first embodiment by the temperature characteristic measuring unit. FIG. 4 is a diagram showing a result of measuring a time change state of a temperature of a joint portion which is a nonconforming product in the first embodiment by a temperature characteristic measuring unit. FIG. 5 is a diagram showing the frequency of occurrence of conforming products and nonconforming products for each value of the feature amount t _{1 in} the first embodiment. FIG. 6 is a diagram showing the frequency of occurrence of conforming products and nonconforming products for each value of the feature amount t _{2 in} the first embodiment. FIG. 7 is a diagram showing the occurrence distribution of conforming products and nonconforming products for each value of the feature amounts t ₁ and t ₂ and threshold boundary lines in the first embodiment. FIG. 8 is a diagram showing the frequency of occurrence of conforming products and nonconforming products for each value of the single index D in the first embodiment. FIG. 9 is a flowchart showing a quality control method for solder joints according to the first embodiment.

  Embodiments of a quality management method and a quality management apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a state during joining in laser soldering according to the first embodiment of the present invention. The component terminal 101 of the electronic component 100 is bonded to the substrate terminal 201 of the resin substrate 200 via the solder 401. The solid thread solder 400 is supplied to the joint at a predetermined timing at a speed v (a function of time) (the supply mechanism of the thread solder 400 is not shown), and the laser beam 300 as a thermal energy supply source has a power p ( (Laser beam irradiation source, alignment mechanism, etc. not shown). As shown in FIG. 1, the temperature rise of the electronic component 100 can be suppressed by locally supplying thermal energy.

FIG. 2 shows an example of a joining condition profile of the yarn solder supply speed v and the laser power p. This joining condition satisfies the following two joining qualities depending on the heat capacity of the component terminal 101, the board terminal 201, and the wiring in the board below the board terminal 201, the amount of solder necessary for joining, and the like. The design requirements are determined as appropriate, and are not limited to the profile shown in FIG.
(Joint Quality 1) Solder is transferred to the joint by an appropriate amount, spreads and spreads to form a fillet, and a good metal joint interface is formed, thereby ensuring the joint reliability.
(Joint quality 2) Thermal degradation (hereinafter referred to as interface degradation) does not occur at the interface between the metal under the terminal of the resin substrate and the resin base material due to excessive heat input at the joint.

  Further, instead of supplying the thread solder 400, preliminary solder may be supplied in advance to the component terminal 101, the board terminal 201, or both. The preliminary solder can be formed from a paste-like solder by a known method such as dispenser, screen printing, or plating. Further, preliminary solder and thread solder may be used in combination. In either case, the same problem as shown below occurs.

When supplying thread solder, in addition to the variation in laser power p and thread solder supply speed v in FIG. 2, the time when the laser power p rises to p ₁ and the solder supply speed v changes from v ₁ to v _2. in changing point, such as t _0, the variation of the transient temperature characteristics of the short at the junction of each joint may occur.

  In addition, when the preliminary solder is supplied in advance, the amount of the preliminary solder varies from electrode to electrode, and the heat capacity changes from electrode to electrode.

  In addition to such variations in bonding conditions, there are always variations in wettability due to differences in electrode surface conditions and variations in the heat capacity of the joints (electrode thickness, amount of pre-solder, substrate thickness, etc.). In the case of the local overheating method as in the embodiment, since the phenomenon proceeds in a short time, the influence is remarkable.

  Due to such manufacturing variations, even if a joining condition that satisfies the above (joining quality 1) is appropriately determined, the above (joining quality 2) is not probabilistically satisfied (hereinafter simply referred to as “non-conforming”). May occur. In particular, when the interface deterioration 202 as shown in FIG. 1 occurs, this cannot be detected by an appearance inspection or an electrical inspection, and there is a risk of shipping with a decrease in reliability inherent.

  Existence of non-conformity, for example, reheats the solder part 401 after joining, gives a shearing force (a direction parallel to the substrate surface) to the substrate terminal 201, and breaks the substrate interface 203 between the substrate terminal 201 and the resin substrate 200. Although it can be known with a decrease in strength, since it is a destructive test, it is difficult to inspect 100% by this method.

  In addition, it is possible to set an upper limit to the shearing force and inspect whether it has broken or not, but if it is reheated, what was originally a conforming product will become incompatible, or it will fit by applying too much shearing force. There is a risk of destroying the product. Therefore, a non-destructive inspection method without applying a load such as reheating is desired.

  FIGS. 3 and 4 show the results of measuring the time change of the temperature of the joint (the surface of the transferred solder 401) when soldered under the joining conditions of FIG. 2 by the temperature characteristic measuring means 500 shown in FIG. It is. As a result of the destructive test described above, the one showing the temperature-time characteristics in FIG. 3 was a conforming product, and the one showing the temperature-time characteristics in FIG. 4 was a nonconforming product.

  When the temperature-time characteristics of FIGS. 3 and 4 are overviewed, it can be seen that the joint portion corresponding to FIG. 4 that has become incompatible tends to have a high temperature and a long time during which the temperature is high. Therefore, as a result of collecting a lot of temperature characteristic data of conforming products and nonconforming products and verifying the difference by a statistical method, the following at least two feature quantities may be necessary to distinguish conforming products and nonconforming products. all right.

(Characteristic 1) t ₁ : Time during which the temperature of the joint is equal to or higher than temperature T ₁ . However, (glass transition temperature of substrate −50 ° C.) ≦ T ₁ ≦ (glass transition temperature of substrate + 250 ° C.)

(Characteristic amount 2) t ₂ : Time until the temperature of the joint reaches the temperature T ₂ from the heating start time (time t ₀ ). However, (glass transition temperature of substrate −50 ° C.) ≦ T ₂ ≦ (glass transition temperature of substrate + 250 ° C.)

In this embodiment, since a glass epoxy resin substrate 200 (glass transition temperature 150 ° C.) is used, specifically, t ₁ (feature 1) has a junction temperature of 100 ° C. ≦ T ₁ ≦ 400. This is the time during which the temperature is higher than a certain temperature in the range of ° C. (for example, T ₁ = 300 ° C.). Similarly, t ₂ (feature value 2) is from the time when heating of the joint is started (time t ₀ ) until the temperature reaches a temperature in the range of 100 ° C. ≦ T ₂ ≦ 400 ° C. (eg, T ₂ = 200 ° C.). Shows the time.

The feature amounts t ₁ and t ₂ are calculated by the quality management unit 600 based on the measurement result by the temperature characteristic measurement unit 500 of FIG. Hereinafter, preferred ranges of the temperatures T ₁ and T ₂ that determine the feature value 1 (t ₁ ) and the feature value 2 (t ₂ ) will be described.

The feature amount 1 indicates the degree to which the resin base material 200 existing at the substrate interface 203 is deteriorated by heat at the time t ₁ when the joint is exposed to a temperature T ₁ or higher set in advance. The resin softens at the glass transition temperature, and when it is exposed to a temperature near or above this temperature for a long time, thermal degradation occurs, and the adhesion strength between the metal and the resin at the substrate interface 203 decreases.

At this time, if T ₁ is set to be smaller than (glass transition temperature of the substrate −50 ° C.), a difference in t ₁ hardly occurs at most joint portions, and the discrimination accuracy between the conforming product and the non-conforming product decreases. Also, if you set larger T ₁ from (glass transition temperature + 250 ° C. of the substrate), joint t ₁ becomes zero will account for the majority, as well as determine the accuracy of the products conforming and non-conforming products is lowered.

A feature amount 2 is a time t ₂ until the temperature of the joint reaches the preset temperature T ₂ from the heating start time (time t _{0 in} FIG. 2), and indicates the strength of thermal shock that the substrate interface 203 receives. Shows the degree. That is, as t ₂ is small, will absorb more heat in a short time. When the thermal shock increases, mechanical stress is applied to the substrate interface 203 before the interface deterioration, which is likely to cause incompatibility.

At this time, if you set smaller than the T ₂ (glass transition temperature -50 ° C. of the substrate), for an impact state where the substrate resin is not softened, little affect the welding quality, Compliant incompatible Product discrimination accuracy decreases. Further, when T ₂ is set to be larger than (glass transition temperature of substrate + 250 ° C.), a difference in t ₂ hardly occurs at most joint portions, and the discrimination accuracy between conforming products and non-conforming products similarly decreases.

Further, more suitable values of T ₁ and T ₂ can be set based on actual experimental data by a statistical method such as a known multiple regression analysis. In the present embodiment, T ₁ = 300 ° C. and T ₂ = 200 ° C. are more preferable values, but the present invention is not limited to this.

FIG. 5 and FIG. 6 are diagrams showing the value of the feature quantity 1 (t ₁ ), the value of the feature quantity 2 (t ₂ ), and the occurrence frequency of conforming products and non-conforming products, respectively. By setting suitable T ₁ and T ₂ for any of the feature amounts, it is possible to discriminate between a conforming product and a non-conforming product before and after each of the determination threshold values t _th1 and t _th2 .

However, there are cases where it is not possible to completely distinguish between a conforming product and a nonconforming product with any one feature amount. In FIGS. 5 and 6, when the threshold values t _th1 and t _th2 are determined so as not to cause non-conforming products to flow out, some of the conforming products are regarded as non-conforming products, and conforming products that should originally be shipped are discarded. As a result, both the nonconforming product rate and the manufacturing cost increase. This problem does not change even if a feature amount (for example, maximum temperature) other than the above-described two feature amounts is added.

Therefore, it will be described below that the accuracy of discriminating between a conforming product and a nonconforming product is further improved by combining the two feature quantities into one single index D and using this. When the relationship between the feature quantities t ₁ and t ₂ was examined for a large number of conforming products and non-conforming products, a distribution as shown in FIG. 7 was obtained.

Compliant incompatible products, t ₁ or discrimination and the characteristic quantity of alone with only one of t _2, a logical product of the threshold decision threshold determination and t ₂ of t ₁ (t ₁ > T _th1 and t2 <t _th2 ) cannot be completely discriminated. However, it can be determined before and after the threshold boundary line 900 shown in FIG. That is, if the threshold values t _th1 and t _th2 are functions of each other, it is possible to discriminate between conforming products and non-conforming products.

  If the multidimensional feature value can be converted into a numerical value indicating the position in the direction orthogonal to the boundary line (boundary hyperplane in the case of three or more dimensions) with respect to such a multidimensional (here, two-dimensional) feature value, one scalar It can be determined by the amount. As a method for integrating such a single numerical index D, for example, the Mahalanobis distance in the MT method (Mahalanobis-Taguchi method) and the comprehensive evaluation scale (referred to as Taguchi distance) in the T method (Taguchi method) are known. It has been. Since the latter is simpler, it is more suitable for real-time judgment processing in the soldering process in terms of calculation speed and calculation software memory capacity (Genichi Taguchi, Quality Engineering Handbook, Nikkan Kogyo). (See Shinbunsha, (2007), p.143-147).

  Here, in the process of calculating the single numerical index D by the Taguchi distance, a scale that quantifies the state of the conforming product and the nonconforming product is required. Therefore, any different value may be given, for example, 0 for a conforming product and 1 for a nonconforming product (this value is referred to as a true value for a conforming product and a true value for a nonconforming product). Therefore, when the true value is set as described above, the numerical index D is a value close to 0 for the conforming product, and a value close to 1 or larger than that for the nonconforming product.

Using the numerical index D calculated in this way, the distribution of conforming products and nonconforming products is examined as shown in FIG. As is apparent from FIG. 8, if a threshold value _Dth is provided for the numerical index D, it is possible to discriminate between conforming products and nonconforming products.

As a specific method of obtaining the numerical index D, for example, it may be determined as a weighted addition value of the feature amounts t ₁ and t ₂ . That is, if a coefficient that always takes the same value on the line parallel to the threshold boundary line 900 in FIG. 7 is selected as the weighted addition value of t ₁ and t ₂ , it is set as a single numerical index D. As a result, it is possible to discriminate between a conforming product and a nonconforming product by the above threshold determination.

In the above-described embodiment, two feature amounts have been described, but a single index D can be calculated by the same calculation method even when other feature amounts are added and combined. This single index D is calculated by the quality management means 600, and the quality management means 600 also makes a pass / fail judgment as to whether it is a conforming product or a nonconforming product by comparing the calculated D with the threshold value _Dth .

That is, in the present embodiment, it has been described that the quality management unit 600 serves as all of the feature amount calculation unit, the single index calculation unit, and the pass / fail determination unit. However, the calculation of the feature amounts t ₁ and t ₂ , The calculation of the index D and the above pass / fail judgment may be executed by different devices.

The process described above is summarized in a flowchart as shown in FIG. That is, as shown in FIG. 1, solder 400 and thermal energy 300 are supplied to the joint (step S0). Next, the “temperature-time characteristic” of the joined portion (surface of the solder 401) from the start of supply of thermal energy 300 to the completion of joining is measured by the temperature property measuring means 500 (step S1). Next, from the “temperature-time characteristic” measured by the temperature characteristic measuring means 500, the quality management means 600 calculates a feature quantity including t ₁ and t ₂ (step S2).

Then, from the plurality of feature amounts (t ₁ , t ₂ , x ₁ , x ₂ ,..., X _k ) obtained in step S2, the comprehensive evaluation measure (Taguchi distance) is obtained from the quality management means 600 by the known method described above. Is calculated to obtain a single index D = f (t ₁ , t ₂ , x ₁ , x ₂ ,..., X _k ) (step S3). As a method of obtaining the single index D, the weighted addition values of a plurality of feature amounts may be calculated and obtained as the above-described weighted addition values of t ₁ and t ₂ .

Finally, the quality management means 600 compares the single index D obtained in step S3 with the threshold value _Dth (step S4), and if D < _Dth , determines that it is a conforming product (step S5). If ≧ _Dth , it is determined as a nonconforming product (step S6).

  The quality control method and quality control device for solder joints based on the procedures of the above steps S0 to S6 enables quality control that can accurately inspect the quality of solder joints in real time and non-destructively without an additional inspection process. Become.

However, when the heat capacity differs for each electrode in one substrate due to the size of the substrate electrode, the presence or absence of a via hole in the lower layer of the electrode, etc., the profile of the soldering joint condition shown in FIG. A value suitable for each is set. In that case, the calculation formula of the single numerical index and the threshold value _Dth are individually determined for each electrode using the temperature characteristic data collected for each electrode.

  Further, the sampling period when the temperature characteristic measuring unit 500 collects the temperature-time characteristic is more preferably 0.1 ms or more and 10 ms or less. If the sampling period is shorter than 0.1 ms, the number of data to be processed becomes enormous, the calculation speed becomes slow, and a large amount of memory capacity is required, which is not desirable.

  On the other hand, if the sampling period is longer than 10 ms, the measurement accuracy of the feature amount 1 and the feature amount 2 is lowered, and therefore the accuracy of discrimination of conformity and nonconformity is lowered, which is not desirable. In this embodiment, 1 ms is selected as the sampling period (1000 data in the case of the total time of 1 second required for joining), but the present invention is not limited to this.

  Furthermore, a radiation thermometer is desirable as a means for measuring temperature-time characteristics. For example, the measurement response is better than that of a thermocouple, and the temperature of the solder surface can be measured without contact. Moreover, since it can measure by positioning at the position of a small electrode, it is suitable for a local heating mounting system.

  Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent requirements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and is described in the column of the effect of the invention. When an effect is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention. Furthermore, the constituent elements over different embodiments may be appropriately combined.

  As described above, the solder joint quality control method and quality control device according to the present invention are useful for the quality control of the joint at the time of the solder joint between the resin substrate terminal and the electronic component terminal. Suitable for pass / fail judgment of product conformity or non-conformity based on quality.

_DESCRIPTION OF _SYMBOLS 100 Electronic component 101 Component terminal 200 Resin substrate 201 Board terminal 202 Interface degradation 203 Substrate interface 300 Laser beam 400 Yarn solder 401 Solder part 500 Temperature characteristic measuring means 600 Quality control means 900 Threshold boundary line t _th1 , t _th2 , D _th Threshold S0 to S6 steps

Claims (9)

A quality control method for solder joints formed by supplying solder and local thermal energy on a resin substrate,
Measuring the time-change data of the temperature of the joint during joining;
Obtaining a plurality of feature quantities from the measured data;
Obtaining a single numerical index from a plurality of the characteristic quantities;
Comparing the numerical index with a predetermined threshold to determine whether the joint is compatible or non-compliant,
The plurality of feature quantities are:
The time t _{1 when} the temperature of the junction is equal to or higher than a predetermined temperature T ₁ that satisfies the condition (glass transition temperature of the substrate −50 ° C.) ≦ T ₁ ≦ (glass transition temperature of the substrate + 250 ° C.). When,
The temperature of the joint is determined in advance from the time when heating by the thermal energy is started, and the predetermined T ₂ satisfies the condition of (glass transition temperature of the substrate −50 ° C.) ≦ T ₂ ≦ (glass transition temperature of the substrate + 250 ° C.). quality control method of the solder joint portion, characterized in that it comprises a time t ₂ to reach. _2. The solder joint quality control method according to claim 1, wherein the numerical index is a comprehensive evaluation scale in a T method (Taguchi method) based on time t ₁ and time t ₂ . The numerical indicators, the quality control method of the solder joint of claim 1, which is a weighted sum of the time t ₁ and time t _2.   4. The solder joint quality control method according to claim 1, wherein a sampling cycle for measuring time-dependent data of temperature of the joint is 0.1 ms or more and 10 ms or less. A quality control device for solder joints formed by supplying solder and local thermal energy on a resin substrate,
A temperature characteristic measuring means for measuring time change data of the temperature of the joint during joining;
Feature quantity calculation means for obtaining a plurality of feature quantities from the measured data;
A numerical index calculation means for obtaining a single numerical index from a plurality of the characteristic quantities;
A determination means for comparing the numerical index with a predetermined threshold value to determine whether the joint is conforming or non-conforming,
The plurality of feature quantities are:
The time t _{1 when} the temperature of the junction is equal to or higher than a predetermined temperature T ₁ that satisfies the condition (glass transition temperature of the substrate −50 ° C.) ≦ T ₁ ≦ (glass transition temperature of the substrate + 250 ° C.). When,
The temperature of the joint is determined in advance from the time when heating by the thermal energy is started, and the predetermined T ₂ satisfies the condition of (glass transition temperature of the substrate −50 ° C.) ≦ T ₂ ≦ (glass transition temperature of the substrate + 250 ° C.). A quality control device for a solder joint, characterized in that it includes a time t ₂ until it reaches The numerical index, the quality management system of the solder joint of claim 5, characterized in that the overall evaluation measure at time t ₁ and time t ₂ in basis was T method (Taguchi method). The numerical index, the quality management system of the solder joint of claim 5, characterized in that the weighted sum of the time t ₁ and time t _2.   The quality control device for a solder joint according to claim 5, 6 or 7, wherein a sampling period for measuring data of a temporal change in temperature of the joint is 0.1 ms or more and 10 ms or less.   The quality control apparatus for solder joints according to any one of claims 5 to 8, wherein the temperature characteristic measuring means is a radiation thermometer.

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