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Can I solder a laser diode directly to a PCB?

Chuie

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I am using a laser diode in a device and I am trying to figure out what needs to happen for it to interface with the rest of the electronics. It is a 1W laser diode and the diode will be turned on for 1ms pulses, each pulse going off once every couple minutes. Do I need to worry about a heat sink or can I just solder the diode right to a PCB?
 



Chuie

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I mean soldering to a pcb without module or heat sink. Would that be an unusual thing to do?
 

Cyparagon

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Soldering directly to a PCB is how many drivers are typically interfaced.

Running a high power laser diode without a heat sink typically results in death within seconds. However, since your duty cycle is waaaay down in the ppm area, it's perfectly safe to do. The main drawback is a difficulty in aligning any collimation optics you may require.

What exactly are you trying to do?
 

DarkLord

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I mean soldering to a pcb without module or heat sink. Would that be an unusual thing to do?
It would be unusual to do considering that the diode will have nowhere to dissipate the heat and it may get fried before you even get to turn it on.
 

Encap

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Are you thinking to use a laser diode driver or just applying voltage to the diode.
Describe or diagram the circuit you will power the diode with.

As mentioned above "Exactly what are you trying to do?"
 
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Chuie

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I am using this driver circuit:

Capture.PNG

And this diode:
PL TB450B

I'm toying with a simple device that will keep a tally of a periodic event by leaving a small mark on some wood. It is just a fun side thing.
 

Cyparagon

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Fun side thing. Fair enough.

The problem here as I see it is you're shoving a raw 5V into the diode with no current limiting. 1ms or not, this will likely pop it unless you accidentally manage enough parasitic impedance in your construction. At the very least you're going to need a dropper resistor in series.
 

Lifetime17

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Hi,
Like it was said no heat sink say by by to the diode poof!!! Solder diode pins correctly to the correct polarity on the driver, wire that to the contact board in the host of choice..
Rich:)7C398130-5835-426A-8526-D8AFB34E43AF_1_105_c.jpegE2F4FB8B-03F6-49A1-9F9A-6E22EAC3BC89_1_105_c.jpeg57F5A90A-3B15-42FE-8D90-918FC86DE188_1_105_c.jpeg
 

DarkLord

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To this I say: read a few sample datasheets. It's not an issue.
Soldering temperatures can range from anywhere between 626°F-662°F (330°C-350°C) and the melting region of most solder is 370°F (188°C). Below is a sample data I from OdicForce, and it says for the absolute maximum ratings it has a case temperature of max 50°C and a storage temperature of 75°C. Sure enough, if you leave that iron on the diode for some time, it will eventually kill the diode. This is especially without a heat sink. I've also remembered killing one of my diodes due to excessive heat, not from the driver.
 

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DarkLord

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Hi,
Like it was said no heat sink say by by to the diode poof!!!
That diode in the copper housing is still considered a heat sink. I'm assuming you chose copper since it dissipates the heat faster than the regular silver Aixiz module housings.
 

Cyparagon

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Like it was said no heat sink say by by to the diode poof!!!
Please read the thread before commenting.

1ms every 120 seconds is an average of ~50 microwatts of heat. A bare diode will have no difficulty with that.

for the absolute maximum ratings it has a case temperature of max 50°C and a storage temperature of 75°C. Sure enough, if you leave that iron on the diode for some time, it will eventually kill the diode.
Storage temperature and soldering temperature are VASTLY different parameters, sir.

Here. Here's an example. 1.6W blue from osram. Storage of 85C, but soldering temperature of 260C. :


"BuT CyP", I hear you complain, "mY sOlDeRiNg IrOn iS aT 360C!!2?!"

60/40 lead solder melts at 188C. Lead free solder is only 220. You don't need a 360C iron to melt that. Even if you did, it'd be fine. Really.

Pretty f:)cking ridiculous that this community runs the diode 300% overcurrent without a second thought, but throws a shit fit if the soldering temp is a few degrees over for 3 seconds.
 

Lifetime17

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Hi,
That copper collar around the diode isn't enough sinking .you need to press the diode into a 12mm module for a 5.6mm diode..After you set the driver to a specific setting for that diode and wired you add thermal compound and slide it into one of these heat sinks for the diode to last. your data sheet tells you what you need to follow
Rich:)

CD15AA04-C776-4F68-80AB-DB308454B27C_1_201_a.jpeg
 

DarkLord

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Pretty f:)cking ridiculous that this community runs the diode 300% overcurrent without a second thought, but throws a shit fit if the soldering temp is a few degrees over for 3 seconds.
With all due respect, diodes can be expensive so yea obviously I would give a **** to account for any possible failure. For the record, I don't run my diode "300% overcurrent." Please don't exaggerate. Soldering while it's in its housing is not a problem I thought the user was referring to just soldering directly to the diode without housing or anything at first, as the housing acts as a heat absorber.
 

gazer101

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With all due respect, diodes can be expensive so yea obviously I would give a **** to account for any possible failure. For the record, I don't run my diode "300% overcurrent." Please don't exaggerate. Soldering while it's in its housing is not a problem I thought the user was referring to just soldering directly to the diode without housing or anything at first, as the housing acts as a heat absorber.
Bruh, if you want to get technical take a look at the specific heat capacity of lead solder. The multiply that by the 1g tops of solder you'll be dabbing onto it and the temperature it's at. Then multiply the specific heat capacity of the primary construction metal of the diode by its weight and then multiply by its peak storage temperature. Divide the value you just calculated by the first value you calculated, if it is above 1 then solder cannot possibly heat damage the diode.

I'm not going to do the math for you :p
 




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