Patent Application
20220302674
The present technique relates to a semiconductor laser driving apparatus. Specifically, the present technique relates to a semiconductor laser driving apparatus and electronic equipment including a substrate incorporating a laser driver and a semiconductor laser and a manufacturing method of the semiconductor laser driving apparatus.
In an electronic apparatus having a distance measurement function, a distance measurement system called ToF (Time of Flight) has often been used from the past. ToF is a system in which a light emitting unit irradiates an object with irradiation light of a sine wave or a rectangular wave, a light receiving unit receives the reflected light from the object, and a distance measurement computing unit measures a distance on the basis of a phase difference between the irradiation light and the reflected light. In order to realize such a distance measurement function, there is known an optical module in which a light emitting element and an electronic semiconductor chip for driving the light emitting element are housed in a case and integrated. For example, an optical module that includes a laser diode array mounted in order on an electrode pattern of a substrate and a laser driver that is electrically connected to the laser diode array has been proposed (refer to, for example, PTL 1).
In the related art described above, the laser diode array and the laser driver are integrated and configured as an optical module. However, in the related art, the laser driver is incorporated in the substrate. Thus, when the presence or absence of a defect in the laser driver is to be tested, it is necessary to pull out the terminal of the incorporated laser driver to the surface of the substrate and connect the terminal to a test pad provided on the surface thereof. Therefore, as the number of test pads increases, the substrate needs to be accordingly widened, making it difficult to downsize the semiconductor laser driving apparatus.
The present technique has been developed in view of such a situation, and an object thereof is to easily downsize a semiconductor laser driving apparatus incorporating a laser driver.
The present technique has been made in order to solve the above-described problems, and a first aspect thereof is to provide a semiconductor laser driving apparatus and electronic equipment including the semiconductor laser driving apparatus including a substrate incorporating a laser driver, a semiconductor laser mounted on one surface of the substrate, connection wiring that electrically connects the laser driver and the semiconductor laser to each other with a wiring inductance of 0.5 nanohenries or less, outer walls surrounding a predetermined mounting region that is included in the one surface of the substrate and where the semiconductor laser is mounted, and a test pad provided in a region that is included in the one surface of the substrate but does not correspond to the mounting region. This leads to an effect of deleting a dead space for the test pad from the mounting region.
In addition, in the first aspect, the test pad may be connected to the laser driver. This leads to an effect of testing the laser driver.
In addition, in the first aspect, it is desirable that the connection wiring have a length of 0.5 millimeters or less. In addition, it is more preferable that the connection wiring be 0.3 millimeters or less.
In addition, in the first aspect, the connection wiring may be provided via a connection via provided in the substrate. This leads to an effect of shortening the wiring length.
In addition, in the first aspect, the semiconductor laser may be arranged in such a manner that a part thereof overlaps an upper part of the laser driver. In this case, the semiconductor laser may be arranged in such a manner that a part corresponding to 50% or less of the area thereof overlaps the upper part of the laser driver.
In addition, in the first aspect, the substrate may include a thermal via at a position where the semiconductor laser is mounted. This leads to an effect of promoting heat radiation.
In addition, in the first aspect, a diffusion plate covering an upside of the mounting region surrounded by the outer walls may be further provided.
In addition, in the first aspect, a photodiode that is mounted on the one surface of the substrate to monitor the light intensity of the laser light irradiated from the semiconductor laser may be further provided. This leads to an effect of keeping the output of the semiconductor laser constant.
In addition, in the first aspect, a connection terminal with the outside may be further provided on a surface opposite to the one surface of the substrate. This leads to an effect of securing the connection with the outside. In this case, the connection terminal may be formed by using at least any one of a solder ball, a copper core ball, a copper pillar bump, and a land grid array.
In addition, a second aspect of the present technique is to provide a manufacturing method of a semiconductor laser driving apparatus, the manufacturing method including a step of forming a laser driver on an upper surface of a support plate, a step of forming a substrate incorporating the laser driver, by forming connection wiring of the laser driver, a step of mounting a semiconductor laser on one surface of the substrate and forming connection wiring that electrically connects the laser driver and the semiconductor laser to each other via the connection wiring with a wiring inductance of 0.5 nanohenries or less, a test step of testing the substrate by bringing a probe into contact with a test pad provided in a region that is included in the one surface of the substrate but does not correspond to a predetermined mounting region where the semiconductor laser is mounted, and an outer wall forming step of forming outer walls surrounding the mounting region. This leads to an effect of manufacturing the semiconductor laser driving apparatus in which a dead space for the test pad is deleted from the mounting region.
In addition, in the second aspect, the outer walls may be formed in a region that is included in the one surface of the substrate and where the test pad is provided, in the outer wall forming step. This leads to an effect of manufacturing the semiconductor laser driving apparatus in which a dead space is deleted from the mounting region and the mounting region is surrounded by the outer walls.
In addition, in the second aspect, a dicing step of cutting the substrate along a scribe line may be further provided after the test step, and the test pad may be provided on the scribe line. This leads to an effect of manufacturing plural chips in which a dead space for the test pad is deleted from the mounting region.
Hereinafter, a mode for carrying out the present technique (hereinafter, referred to as an embodiment) will be described. The description will be given in the following order.
1. Embodiment (Semiconductor Laser Driving Apparatus)
2. Application Example (Electronic Equipment)
The semiconductor laser driving apparatus 10 assumes measurement of a distance by ToF. ToF is high in depth accuracy although not as high as the structured light, and has such a characteristic that it can operate in a dark environment without any problem. In addition, ToF is considered to have many advantages as compared with other systems such as the structured light and the stereo camera in terms of the simplicity of the apparatus configuration and cost.
In the semiconductor laser driving apparatus 10, a semiconductor laser 300, a photodiode 400, and a passive component 500 are electrically connected by wire bonding and mounted on the surface of a substrate 100 incorporating a laser driver 200. As the substrate 100, a printed wiring board is assumed.
The semiconductor laser 300 is a semiconductor device that emits laser light by allowing a current to flow through a PN junction of a compound semiconductor. Here, as the compound semiconductor to be used, for example, aluminum gallium arsenide (AlGaAs), indium gallium arsenide phosphorus (InGaAsP), aluminum gallium indium phosphorus (AlGaInP), gallium nitride (GaN), and the like are assumed.
The laser driver 200 is a driver integrated circuit (IC) for driving the semiconductor laser 300. The laser driver 200 is incorporated in the substrate 100 in a face-up state. Regarding the electrical connection between the laser driver 200 and the semiconductor laser 300, since the wiring inductance needs to be reduced, it is desirable to make the wiring length as short as possible. This specific value will be described later.
The photodiode 400 is a diode for detecting light. The photodiode 400 is used for APC (Automatic Power Control) for maintaining the output of the semiconductor laser 300 constant by monitoring the light intensity of the semiconductor laser 300.
The passive component 500 is a circuit component other than active elements such as a capacitor and a resistor. The passive component 500 includes a decoupling capacitor for driving the semiconductor laser 300.
Hereinafter, an axis perpendicular to the substrate 100 will be referred to as a “Z axis.” In addition, a predetermined axis parallel to the substrate 100 will be referred to as an “X axis,” and an axis perpendicular to the X axis and the Z axis will be referred to as a “Y axis.”
As exemplified in
In addition, when viewed from the Z direction, side walls 600 are formed on the surface of the substrate 100 so as to surround a rectangular predetermined region where the semiconductor laser 300 is mounted. Of the surface of the substrate 100, the rectangular region surrounded by the side walls 600 will hereinafter be assumed as a “mounting region.” The region surrounded by the thick line in
A predetermined number of test pads such as test pads 103 and 104 are provided in regions that are included in the surface of the substrate 100 but that do not correspond to the mounting region, in other words, below the side walls 600. The test pad 103 and the like are pads used for testing components (the laser driver 200 and the like) and circuits incorporated in the substrate 100. For example, the test pads 103 and 104 are electrically connected to the laser driver 200 via signal lines 105 and 106 and used for testing the laser driver 200.
In addition, a diffusion plate 700 covers the upside of the mounting region of the substrate 100. The space surrounded by the mounting region of the substrate 100, the side walls 600, and the diffusion plate 700 is called a cavity. Thus, the semiconductor laser driving apparatus 10 has a hollow cavity structure.
As described above, the substrate 100 incorporates the laser driver 200, and the semiconductor laser 300 and the like are mounted on the surface thereof. The connection between the semiconductor laser 300 and the laser driver 200 is made via the connection via 101. The wiring length can be shortened by using the connection via 101. It should be noted that the connection via 101 is an example of the connection wiring described in the claims.
In addition, the substrate 100 includes a thermal via 102 for heat radiation. Each component mounted on the substrate 100 is a heat generating source, and heat generated in each component can be radiated from the rear surface of the substrate 100 by using the thermal via 102.
The semiconductor laser 300, the photodiode 400, and the passive component 500 mounted on the surface of the substrate 100 are surrounded by the side walls 600. As a material of the side walls 600, for example, a plastic material or metal is assumed.
The upper surface surrounded by the side walls 600 is covered with the diffusion plate 700. The diffusion plate 700 is an optical element for diffusing the laser light from the semiconductor laser 300, and is also called a diffuser.
As described above, since the connection between the semiconductor laser 300 and the laser driver 200 is assumed to be made via the connection via 101, the semiconductor laser 300 and the laser driver 200 are arranged while being overlapped one on another when viewed from the upper surface. On the other hand, it is desirable to provide a thermal via 102 on the lower surface of the semiconductor laser 300, and it is also necessary to secure a region therefor. Accordingly, in order to clarify the positional relation between the laser driver 200 and the semiconductor laser 300, the amount of overlap between the two is defined as follows.
In the arrangement illustrated in a of
Then, in the arrangement illustrated in b of
In the embodiment, the overlap amount is desirably larger than 0% to provide a region for the above-described connection via 101. On the other hand, when considering that a certain number of thermal vias 102 are to be arranged directly under the semiconductor laser 300, the overlap amount is desirably 50% or less. Thus, by making the overlap amount larger than 0% but 50% or less, the wiring inductance is reduced, and excellent heat radiation characteristics can be obtained.
As described above, the wiring inductance becomes a problem in the connection between the semiconductor laser 300 and the laser driver 200. All conductors have an inductive component, and even an inductance of an extremely short lead wire may cause adverse effects in high frequency regions such as a ToF system. That is, when a high frequency operation is performed, the driving waveform for driving the semiconductor laser 300 from the laser driver 200 is distorted due to the influence of the wiring inductance, and the operation may become unstable.
Here, a theoretical equation for calculating the wiring inductance is examined. For example, the inductance IDC [pH] of a straight lead wire having a circular cross section with a length L [mm] and a radius R [mm] is represented in free space by the following equation. Note that In represents the natural logarithm.
IDC=0.0002L·(1n(2L/R)−0.75)
In addition, for example, the inductance IDC [μH] of a strip line (substrate wiring pattern) having a length L [mm], a width W [mm], and a thickness H [mm] is represented in free space by the following equation.
IDC=0.0002L·(1n(2L/(W+H))+0.2235((W+H)/L)+0.5)
In the case of a semiconductor laser driving apparatus such as a ToF system, when assuming to drive at several hundred megahertz, the wiring inductance is desirably 0.5 nH or less, and more preferably 0.3 nH or less. Thus, when considering the above-described preliminary calculation result, it is considered that the wiring length between the semiconductor laser 300 and the laser driver 200 is desirably 0.5 millimeters or less, and more preferably 0.3 millimeters or less.
First, as illustrated in a of
Next, as illustrated in b of
Then, as illustrated in c of
Subsequently, as illustrated in d of
Then, as illustrated in e of
Next, as illustrated in f of
First, as illustrated in a of
As the support plate 110, a substrate made of an inorganic material, a metal material, a resin material, or the like can be used. For example, silicon (Si), glass, ceramic, copper, a copper-based alloy, aluminum, an aluminum alloy, stainless steel, a polyimide resin, or an epoxy resin can be used.
The carrier copper foil 131 having a thickness of 18 to 35 micrometers is vacuum-adhered to the ultra-thin copper foil 132 having a thickness of 2 to 5 micrometers, to be used as the peelable copper foil 130. As the peelable copper foil 130, for example, 3FD-P3/35 (made by Furukawa Circuit Foil Co., Ltd.), MT-18S5DH (made by MITSUI MINING & SMELTING CO., LTD.), or the like can be used.
As a resin material of the adhesive resin layer 120, an organic resin containing a reinforcing material of a glass fiber, such as an epoxy resin, a polyimide resin, a PPE resin, a phenol resin, a PTFE resin, a silicon resin, a polybutadiene resin, a polyester resin, a melamine resin, a urea resin, a PPS resin, and a PPO resin can be used. In addition, as the reinforcing material, an aramid nonwoven fabric, an aramid fiber, a polyester fiber, or the like can be used in addition to the glass fiber.
Next, as illustrated in b of
Then, as illustrated in c of
Subsequently, as illustrated in d of
Then, as illustrated in e of
Next, as illustrated in f of
Then, as illustrated in g of
Next, after the roughening treatment, an electroless plating treatment is performed on the wall surface of the via hole 170 and the surface of the interlayer insulating resin 161. Then, a photosensitive resist is pasted by roll laminating on the surface of the interlayer insulating resin 161 subjected to the electroless plating treatment. As the photosensitive resist in this case, for example, a photosensitive plating resist film of a dry film can be used. The photosensitive plating resist film is exposed and then developed, so that a plating resist pattern with the portion of the via hole 170 and the portion of the wiring pattern being opened is formed. Subsequently, the opening portions of the plating resist pattern are subjected to a treatment of applying an electrolytic copper plating having a thickness of 15 micrometers. Then, the plating resist is peeled off, and the electroless plating remaining on the interlayer insulating resin is removed by flash etching using a sulfuric acid hydrogen peroxide mixture or the like, so that the via hole 170 filled with copper plating and the wiring pattern as illustrated in h of
Subsequently, as illustrated in i of
Then, as illustrated in j of
Next, as illustrated in k of
Here, the shallow via hole 171 is a filled via filled with copper plating. Each of the size and depth of the via is approximately 20 to 30 micrometers. In addition, the size of the diameter of the land is approximately 60 to 80 micrometers.
On the other hand, the deep via hole 172 is what is generally called a conformal via in which copper plating is applied only to the outside of the via. Each of the size and depth of the via is approximately 80 to 150 micrometers. In addition, the size of the diameter of the land is approximately 150 to 200 micrometers. It should be noted that it is desirable that the deep via hole 172 be arranged via an insulating resin of approximately 100 micrometers from the outer shape of the laser driver 200.
Next, as illustrated in m of
Subsequently, as illustrated in n of
Then, as illustrated in o of
Next, as illustrated in p of
In addition, a BGA (Ball Grid Array) of solder balls may be mounted on the land for external connection by printing and applying cream solder as a connection terminal. In addition, as the connection terminal, a copper core ball, a copper pillar bump, a land grid array (LGA), or the like may be used.
The semiconductor laser 300, the photodiode 400, and the passive component 500 are mounted on the surface of the substrate 100 thus manufactured as described above, and the side walls 600 and the diffusion plate 700 are attached thereto, as illustrated in q of
It should be noted that, although the example of using the peelable copper foil 130 and the support plate 110 has been described in the above process, a copper clad laminate (CCL) can be used instead. In addition, as the manufacturing method of incorporating the component into the substrate, a method of forming a cavity in the substrate and mounting the same may be used.
Next, a manufacturing process performed between p and q in
As exemplified in a of
Then, as exemplified in b of
Next, the test apparatus 900 tests the substrate 100. The test is performed for each chip on the substrate 100. After the test, the substrate 100 is divided into plural chips by dicing, and chips having a bad test result are discarded.
The semiconductor laser 300 is mounted on a chip having a good test result. Then, the side walls 600 are formed in regions where the test pad 103 and the like are provided. Next, the diffusion plate 700 is provided.
As described above, in the semiconductor laser driving apparatus 10, the test pads 103 and 104 are arranged in the regions that are included in the surface of the substrate 100 but that do not correspond to the mounting region (in other words, below the side walls 600). The regions where these test pads are provided are not used after the test process. Thus, if the test pads are provided in the mounting region, the regions become useless dead spaces after the test.
If the test pads 103 and 104 are provided below the side walls 600, it is not necessary to provide the test pad 103 and the like in the mounting region, and the mounting area of the substrate 100 can be reduced by eliminating the dead spaces. Accordingly, the semiconductor laser driving apparatus can easily be downsized.
It should be noted that the dead spaces on the surface side of the substrate 100 can also be reduced even by a method of providing the test pads on both the surface and the rear surface of the substrate 100. However, in this method, it is necessary to bring the probes into contact with both surfaces of the substrate 100 at the time of the test, and there is a risk that the test becomes complicated and the cost is increased. If the test pads 103 and 104 are provided below the side walls 600, it is only necessary to bring the probes into contact with only the surface side of the substrate 100, and thus the cost relating to the test can be reduced as compared to a case in which the test pads are provided on both surfaces.
As described above, according to the modified example of the embodiment of the present technique, since the test pads 103 and 104 are provided in the regions that are included in the surface of the substrate 100 but that do not correspond to the mounting region, the mounting region can be reduced as compared to a case in which the test pad 103 and the like are provided in the mounting region. Accordingly, the semiconductor laser driving apparatus 10 can easily be downsized.
Although the test pads 103 and 104 are provided on the surface of the substrate 100 below the side walls 600 in the above-described embodiment, these test pads can also be provided on scribe lines. Here, the scribe lines are cutting margin portions that are provided in advance between plural chips, to be used when the substrate is divided into the chips by dicing. A substrate 100 according to a modified example of the embodiment differs from that of the embodiment in that the test pad 103 and the like are provided on the scribe lines.
As exemplified in a of
Here, the test pads 103 and 104 are provided on the scribe lines in the substrate 100 of the modified example of the embodiment. In a of
Then, as exemplified in b of
Next, the test apparatus 900 tests the substrate 100. The test is performed for each chip on the substrate 100.
As exemplified in a of
Then, as exemplified in b of
By providing the test pad 103 and the like on the scribe lines, it is not necessary to provide the test pad 103 and the like in the mounting region, and the mounting region of the substrate 100 can be accordingly reduced.
As described above, according to the modified example of the embodiment of the present technique, since the test pad 103 and the like are provided on the scribe lines that do not correspond to the mounting region, the mounting region can be reduced as compared to a case in which the test pad 103 and the like are provided in the mounting region. Accordingly, the semiconductor laser driving apparatus 10 can easily be downsized.
The electronic equipment 800 is a portable terminal in which the semiconductor laser driving apparatus 10 according to the above-described embodiments is mounted. The electronic equipment 800 includes an imaging unit 810, a semiconductor laser driving apparatus 820, a shutter button 830, a power button 840, a control unit 850, a storage unit 860, a wireless communication unit 870, a display unit 880, and a battery 890.
The imaging unit 810 is an image sensor for imaging a subject. The semiconductor laser driving apparatus 820 is the semiconductor laser driving apparatus 10 according to the above-described embodiments.
The shutter button 830 is a button for giving an instruction on an imaging timing in the imaging unit 810 from the outside of the electronic equipment 800. The power button 840 is a button for giving an instruction on on/off of the power of the electronic equipment 800 from the outside of the electronic equipment 800.
The control unit 850 is a processing unit that controls the entire electronic equipment 800. The storage unit 860 is a memory for storing data and programs necessary for the operation of the electronic equipment 800. The wireless communication unit 870 performs wireless communication with the outside of the electronic equipment 800. The display unit 880 is a display for displaying an image or the like. The battery 890 is a power supply source for supplying power to each unit of the electronic equipment 800.
The imaging unit 810 detects the light receiving amount from 0 to 180 degrees as Q1 and detects the light receiving amount from 180 to 360 degrees as Q2 with a specific phase (for example, rising timing) of a light emission control signal for controlling the semiconductor laser driving apparatus 820 defined as 0 degree. In addition, the imaging unit 810 detects the light receiving amount from 90 to 270 degrees as Q3 and detects the light receiving amount from 270 to 90 degrees as Q4. The control unit 850 computes a distance d to an object by the following equation on the basis of these light receiving amounts Q1 to Q4, and displays the distance d on the display unit 880.
d=(c/4nf)×arctan{(Q3−Q4)/(Q1−Q2)}
The unit of the distance d in the above equation is, for example, meters (m). In the equation, c is the speed of light, and the unit thereof is, for example, meters per second (m/s). In the equation, arctan is the inverse function of a tangent function. The value of “(Q3−Q4)/(Q1−Q2)” indicates a phase difference between the irradiated light and the reflected light. In the equation, n indicates the ratio of the circumference of a circle to its diameter. In addition, f is the frequency of the irradiated light, and the unit thereof is, for example, megahertz (MHz).
The electronic equipment 800 is housed in a housing 801, includes the power button 840 on a side surface, and includes the display unit 880 and the shutter button 830 on the front surface. In addition, optical regions of the imaging unit 810 and the semiconductor laser driving apparatus 820 are provided on the rear surface.
Accordingly, the display unit 880 can display not only a normal captured image 881 but also a depth image 882 according to the distance measurement result using ToF.
It should be noted that, in the application example, a portable terminal such as a smartphone is exemplified as the electronic equipment 800, but the electronic equipment 800 is not limited thereto, and may be, for example, a digital camera, a game machine, wearable equipment, or the like.
It should be noted that the above-described embodiments illustrate an example for embodying the present technique, and the matters in the embodiments have corresponding relations with the matters specifying the invention in the claims. Similarly, the matters specifying the invention in the claims have corresponding relations with the matters in the embodiments of the present technique to which the same names are given. However, the present technique is not limited to the embodiments, and can be embodied by applying various modifications to the embodiments without departing from the gist thereof.
It should be noted that the effects described in the specification are merely illustrative and not limitative, and other effects may be provided.
It should be noted that the present technique can also be configured as follows.
(1) A semiconductor laser driving apparatus including:
a substrate incorporating a laser driver;
a semiconductor laser mounted on one surface of the substrate;
connection wiring that electrically connects the laser driver and the semiconductor laser to each other with a wiring inductance of 0.5 nanohenries or less;
outer walls surrounding a predetermined mounting region that is included in the one surface of the substrate and where the semiconductor laser is mounted; and
a test pad provided in a region that is included in the one surface of the substrate but does not correspond to the mounting region.
(2) The semiconductor laser driving apparatus according to (1),
in which the test pad is connected to the laser driver.
(3) The semiconductor laser driving apparatus according to (1) or (2)
in which the connection wiring has a length of 0.5 millimeters or less.
(4) The semiconductor laser driving apparatus according to any one of (1) to (3),
in which the connection wiring is provided via a connection via provided in the substrate.
(5) The semiconductor laser driving apparatus according to any one of (1) to (4),
in which the semiconductor laser is arranged in such a manner that a part thereof overlaps an upper part of the laser driver.
(6) The semiconductor laser driving apparatus according to (5),
in which the semiconductor laser is arranged in such a manner that a part corresponding to 50% or less of an area thereof overlaps the upper part of the laser driver.
(7) The semiconductor laser driving apparatus according to any one of (1) to (6),
in which the substrate includes a thermal via at a position where the semiconductor laser is mounted.
(8) The semiconductor laser driving apparatus according to any one of (1) to (7), further including:
a diffusion plate covering an upside of the mounting region surrounded by the outer walls.
(9) The semiconductor laser driving apparatus according to any one of (1) to (8), further including:
a photodiode that is mounted on the one surface of the substrate to monitor light intensity of the laser light irradiated from the semiconductor laser.
(10) The semiconductor laser driving apparatus according to any one of (1) to (9), further including:
a connection terminal for establishing connection with an outside on a surface opposite to the one surface of the substrate.
(11) The semiconductor laser driving apparatus according to (10),
in which the connection terminal is formed by using at least any one of a solder ball, a copper core ball, a copper pillar bump, and a land grid array.
(12) Electronic equipment including:
a substrate incorporating a laser driver;
a semiconductor laser mounted on one surface of the substrate;
connection wiring that electrically connects the laser driver and the semiconductor laser to each other with a wiring inductance of 0.5 nanohenries or less;
outer walls surrounding a predetermined mounting region that is included in the one surface of the substrate and where the semiconductor laser is mounted; and
a test pad provided in a region that is included in the one surface of the substrate but does not correspond to the mounting region.
(13) A manufacturing method of a semiconductor laser driving apparatus, including:
a step of forming a laser driver on an upper surface of a support plate;
a step of forming a substrate incorporating the laser driver, by forming connection wiring of the laser driver;
a step of mounting a semiconductor laser on one surface of the substrate and forming connection wiring that electrically connects the laser driver and the semiconductor laser to each other via the connection wiring with a wiring inductance of 0.5 nanohenries or less;
a test step of testing the substrate by bringing a probe into contact with a test pad provided in a region that is included in the one surface of the substrate but does not correspond to a predetermined mounting region where the semiconductor laser is mounted; and
an outer wall forming step of forming outer walls surrounding the mounting region.
(14) The manufacturing method of the semiconductor laser driving apparatus according to (13),
in which the outer walls are formed in a region that is included in the one surface of the substrate and where the test pad is provided, in the outer wall forming step.
(15) The manufacturing method of the semiconductor laser driving apparatus according to (13), further including:
a dicing step of cutting the substrate along a scribe line after the test step,
in which the test pad is provided on the scribe line.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-161257 | Sep 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/030651 | 8/12/2020 | WO |
