JP4983267B2 - Electronic component mounting method - Google Patents

Description

The present invention relates to an electronic component mounting method for mounting an electronic component by determining whether or not the electrode state after solder transfer including the missing electrode is good.

2. Description of the Related Art Conventionally, a paste supply device that supplies paste to bumps (electrodes) for connecting electronic components is known (see Patent Document 1). The paste supply device is disposed on a mounting line for electronic components, and has a function of immersing bumps of electronic components before mounting in paste-like solder and transferring the solder to the bumps. In the electronic component to which the solder has been transferred, bumps are mounted on lands (electrodes) formed on the substrate, and the solder is melted by subsequent reflow, whereby solder joining between the two electrodes is performed.
Japanese Patent No. 3289604

  In order to maintain the mounting quality by such solder bonding at a high level, it is confirmed prior to mounting whether or not the solder responsible for the electrical and physical bonding between the electronic component and the board is accurately transferred to the bump. There is a need. At the same time, it is necessary to confirm the absence of the bump itself and to remove the electronic component in which the loss has occurred from the mounting line.

  However, conventionally, there has been no appropriate technique for accurately and quickly confirming the solder transfer state and the missing bump. Therefore, it is necessary to confirm the missing bump separately from the confirmation of the solder transfer state, which leads to a decrease in the throughput of mounting, and because the confirmation is not performed accurately, the missing bump component is mistaken as a good product. There are cases where mounting is performed as it is, causing problems such as poor quality.

Therefore, an object of the present invention is to provide an electronic component mounting method for mounting an electronic component by determining whether the electrode state after solder transfer including a missing bump is good.

An electronic component mounting method of the present invention is an electronic component mounting method for determining a state of an electrode formed on an electronic component and mounting the electronic component on a substrate, after the paste-like solder is transferred to the electrode a detection step of detecting the luminance of the area where the electrodes, the luminance at the area where the electrode is a photoelectric device in which the photoelectric elements the number of receiving light intensity that exceeded the first threshold corresponding to the entire transfer surface of the electrode the electrode is determined as a defective soldering state when the brightness abnormal ratio is a percentage of the number is Tsu exceeded the allowable ratio, luminance in the area where the electrodes of the first and second thresholds And when the luminance abnormality ratio, which is the ratio of the number of photoelectric elements that have received light with luminance exceeding the first threshold to the number of photoelectric elements corresponding to the entire transfer surface of the electrode, is below the allowable ratio The electrode is good solder It determines that the state, determines that the brightness in the area where the electrode is the electrode when it is below the second threshold and a and determining step is an electrode missing state, lies in Handa poor state If this happens, an error warning to that effect is issued, and error processing to retry the transfer operation or to perform error processing to exclude the electronic component from the mounting target is performed, and even if it is determined that the electrode is missing, an error warning to that effect is also output. Then, error processing for removing the electronic component from the mounting target is performed, and the electronic component determined to be in the good solder state and the electronic component determined to be in the good solder state after the transfer retry are mounted on the substrate.

  According to the present invention, since the quality of the electrode state after the paste transfer including the missing electrode is determined based on the brightness of the electrode forming portion, it is possible to simplify the apparatus and process required for the determination, and to reduce the cost. Improvement in production efficiency can be realized.

  Embodiments of the present invention will be described with reference to the drawings. 1 is an overall configuration diagram of an electronic component mounting apparatus according to an embodiment of the present invention, FIG. 2 is a configuration diagram of an electrode state determination apparatus according to an embodiment of the present invention, and FIG. 3 is a relationship between brightness and threshold at a bump formation location. FIG. 4 is a flowchart showing the procedure of the electrode state determination method according to the embodiment of the present invention.

  First, an electronic component mounting apparatus according to an embodiment of the present invention will be described. In FIG. 1, a base 1 is a base of an electronic component mounting apparatus. The board transport device 2 disposed substantially at the center of the base 1 carries the board 3 before mounting into the electronic component mounting apparatus and carries out the board 3 after mounting from the electronic component mounting apparatus. The substrate transfer device 2 is provided with a substrate fixing device that clamps and fixes the substrate 3, and temporarily fixes the substrate 3 being mounted at a predetermined position. The electronic component supply device 4 disposed on both sides of the substrate transfer device 2 sequentially supplies a plurality of electronic components accommodated in the supply port 5. The supplied electronic component is picked up by the mounting head 6 and mounted on the substrate 3. The mounting head 6 is supported by the orthogonal robot 7 disposed on the base 1 so as to be horizontally movable above the base 1.

  Two types of cameras 10, 11, a paste transfer unit 12, and an electronic component recovery unit 13 are disposed between the substrate transport device 2 and the electronic component supply device 4. The first camera 10 is an imaging device that images an electronic component picked up by the mounting head 6 from below, and pattern analysis is performed on the outer shape of the electronic component from the captured electronic component image to determine the position and angle of the electronic component. Recognize. The mounting head 6 mounts an electronic component whose position and angle are corrected based on the recognition result on the substrate 3. The paste transfer unit 12 stores paste-like solder at the top. This solder is used to join the electrode of the electronic component and the electrode of the substrate 3. When the electronic component picked up by the mounting head 6 is immersed in the paste stored in the paste transfer unit 12 with the electrode facing downward, the solder is transferred to the electrode. It has become so. The second camera 11 is an imaging device that images the electrode after paste transfer, and includes a CCD, a CMOS, or the like in which a plurality of photoelectric elements that sense reflected light from the imaging target are arranged in a grid pattern.

  Next, an electrode state determination apparatus according to an embodiment of the present invention will be described. In FIG. 2, the electrode state determination device includes a second camera 11, a luminance detection unit 14, a storage unit 17, and an electrode state determination unit 18. The luminance detection unit 14 has a function as luminance detection means for detecting the luminance of the imaging target based on the intensity of the reflected light sensed by the plurality of photoelectric elements of the second camera 11. Since the imaging object of the second camera 11 is the metal bump 16 that forms the external connection electrode of the electronic component 15, the reflectance is high and the detection is performed with a high level of brightness (see FIG. 3A). . On the other hand, when the paste is transferred to the bumps 16, the reflectance is lowered, so that the bumps 16 to which the paste has been transferred are detected with a low level of brightness (see FIG. 3B). Further, when the bump 16 is missing, the missing part is in a state in which the resin casing of the electronic component 15 is exposed, so that it hardly reflects light and is detected at a lower level of brightness (FIG. 3). (See (d)).

The memory | storage part 17 has a function as a memory | storage means to memorize | store two threshold values preset to predetermined brightness | luminance. Among these, as shown in FIG. 3, the first threshold value TH1 is set between the luminance of the bump 16 when the paste is transferred and the luminance of the bump 16 when the paste is not transferred. The threshold value TH2 of 2 is set between the luminance of the bump 16 in a state where the paste is transferred and the luminance at the bump missing portion.

  The electrode state determination unit 18 has a function as a determination unit that determines the electrode state by comparing the luminance detected by the luminance detection unit 14 with two threshold values stored in the storage unit 17. The electrode state has three modes: a good solder state in which an appropriate amount of paste is transferred to the entire bonding surface of the bump 16, a poor solder state in which an appropriate amount is not transferred, and a bump missing state in which bumps are missing. The electrode state determination unit 18 is in a soldering failure state when the luminance detected by the luminance detection unit 14 exceeds the first threshold value, and is soldered when the luminance is between the first threshold value and the second threshold value. When it is in a good state and is below the second threshold, it is determined that the bump is missing.

  In FIG. 3 (c), when there is uneven transfer on the transfer surface of the bump 16, the region where the appropriate amount of paste is transferred (transfer good region) 16a exhibits a luminance lower than the first threshold value, and the appropriate amount of paste is transferred. In the unfinished region (transfer defective region) 16b, the luminance exceeding the first threshold value may be exhibited. Depending on the type of substrate or electronic component, even if there is a certain amount of transfer unevenness, it may be acceptable in terms of bonding quality, so the number of photoelectric elements that receive light with a luminance exceeding the first threshold corresponds to the entire transfer surface of the bump 16. The quality of the electrode state is determined based on the ratio of the number of photoelectric elements to be performed (hereinafter referred to as the luminance abnormality ratio). The storage unit 17 stores a preset allowable value (allowable ratio) corresponding to the type of board or electronic component. When the luminance abnormality ratio is below the allowable ratio, the storage unit 17 falls below the first threshold value. It is determined that the solder is in a good state, and when the luminance abnormality ratio is higher than the allowable ratio, it is treated as if it is higher than the first threshold value, and it is determined that the solder is in a defective state. Is done.

  The warning unit 19 issues an error warning when the bump 16 after paste transfer is in a solder failure state or in a bump missing state.

  Next, a method for determining the electrode state using the electrode state determination device will be described with reference to the flowchart of FIG. First, the first threshold value TH1 and the second threshold value TH2 that are the determination criteria of the electrode state are taken into consideration in consideration of the amount of solder, the transfer area, and the like required for the substrate to be mounted and the type of electronic component in the electronic component mounting apparatus. An allowable value is set (ST1). Next, the formation location of the bump 16 after paste transfer is positioned within the field of view of the second camera 11, and the luminance at the location is detected (ST2). Next, the detected luminance is compared with the first threshold value and the second threshold value (ST3). When the detected luminance is between the first threshold value and the second threshold value, it is determined that the solder is in a good state (ST4). On the other hand, when the detected luminance exceeds the first threshold, it is determined that the solder is in a defective state (ST5). On the other hand, when the detected luminance is lower than the second threshold, it is determined that the bump is missing (ST6).

  If it is determined that the solder is in a defective state, an error warning to that effect is issued (ST7), and error processing such as retrying the transfer operation or removing the electronic component from the mounting target is performed (ST8). Further, when it is determined that the bump is missing, an error warning to that effect is issued (ST9), and error processing such as removing the electronic component from the mounting target is performed (ST10). The electronic component determined to be in a good solder state (ST4) and the electronic component determined to be in a good solder state after transfer retry (ST8) (ST4) are mounted on the substrate (ST11).

According to the electrode state determination device and the electrode state determination method of the present embodiment, it is possible to determine the quality of the electrode state after paste transfer including the missing electrode based on the luminance of the bump formation location. And the process can be simplified, and the cost can be reduced and the production efficiency can be improved. In addition, electronic components with missing electrodes or solder defects are detected by quantitative determination based on luminance and excluded from mounting targets, so electronic components that have a problem in bonding reliability must be mounted. It is possible to avoid the product quality deterioration due to.

  According to the present invention, since the quality of the electrode state after the paste transfer including the missing electrode is determined based on the brightness of the electrode forming portion, it is possible to simplify the apparatus and process required for the determination, and to reduce the cost. It has the advantage that improvement in production efficiency can be realized, and is useful in the field of mounting electronic components.

1 is an overall configuration diagram of an electronic component mounting apparatus according to an embodiment of the present invention. The block diagram of the electrode state determination apparatus of embodiment of this invention Explanatory drawing showing the relationship between brightness and threshold at bump formation locations The flowchart which shows the procedure of the electrode state determination method of embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 2nd camera 14 Luminance detection part 15 Electronic component 16 Bump 17 Memory | storage part 18 Electrode state determination part TH1 1st threshold value TH2 2nd threshold value

Claims (1)

An electronic component mounting method for determining a state of an electrode formed on an electronic component and mounting the electronic component on a substrate,
A detection step of detecting a luminance at a position where the electrode is formed after the paste-like solder is transferred to the electrode;
On the luminance abnormal ratio is allowable percentage brightness is a ratio of the first number of photoelectric elements receives light intensity that exceeded the threshold occupies the photoelectric number of elements corresponding to the entire transfer surface of the electrode in the area where the electrode the electrode is determined as a defective soldering state when being Tsu times,
The number of photoelectric elements corresponding to the entire transfer surface of the electrode when the luminance at the electrode formation location is between the first threshold value and the second threshold value, and the number of photoelectric elements receiving the light with the luminance exceeding the first threshold value And determining that the electrode is in a good solder state when the luminance abnormality ratio, which is a ratio to the ratio, is lower than the allowable ratio ,
A determination step of determining that the electrode is in an electrode missing state when the luminance at a position where the electrode is formed is lower than a second threshold,
When it is determined that the solder is in a defective state, an error warning to that effect is issued, retrying the transfer operation or performing error processing to exclude the electronic component from the mounting target,
When it is determined that there is an electrode missing state, an error warning to that effect is issued, and error processing is performed to exclude the electronic component from the mounting target.
An electronic component mounting method, wherein an electronic component determined to be in a good solder state and an electronic component determined to be in a good solder state after transfer retry are mounted on a substrate.

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