Introduction: How to Surface Mount Solder Using Solder Paste

Picture of How to Surface Mount Solder Using Solder Paste

Quick tutorial showing how to solder a Attiny85 package type SOIC-8 using a hot air tool and solder paste.

SOIC is just one of the many types of standarized packages that integrated circuits such as the Attiny85 can come in. The package type just indicates the components will look different and have the chip's legs accessible in different styles.

This is a free hand soldering paste technique using a Hot Air Soldering Rework Station but you are more than welcome to make a stencil from OSH Stencils!

Questions, Concerns , Compliments, Feedback all welcomed:

@NemesisContrer8

Step 1: What You Will Need

Picture of What You Will Need

1. SMD291SNL ‑ Chip Quik Solder Paste (recommended to use because it comes w/ a fine tip syringe)

2. PCB board (I'll be using Adafruit's SOIC-8 breakout board)

3. Components being soldered (I'm using the ATtiny85)

4. Fine tip tweezers

5. Hot Air Soldering Rework Station/ Or a skillet,oven you feel comfortable using for SMD work

Step 2: Find Something to Hold Down the PCB

Picture of Find Something to Hold Down the PCB

I'll be using my favorite vise the PanaVise 350 Multi-Purpose Work Center.

However , use whatever works best for you (small vise, tape, wood,clamp etc)

Step 3: Dispense Solder Paste Onto the Copper Traces

Picture of Dispense Solder Paste Onto the Copper Traces

Squirt a line that spreads over the golden pads (copper pads)

Don't worry about getting the solder paste on the blue part of the PCB (solder mask)

Once the board is heated the solder mask will repel the solder paste to shrink & harden onto the copper pads

Step 4: Apply Heat to the Board

Picture of Apply Heat to the Board

I used a the Hot Air Soldering Rework Station - Quick 957D under low air control at about 370°C

Alternatives include kitchen : skillets and small ovens just use with caution and continuous monitoring


The solder paste go through transitions from liquid-->dusty-->shrinking till it finally hardens

Step 5: Finished!

Picture of Finished!

Here is the finished Attiny85 SOIC 8 pin package type soldered into the breakout board

-Happy soldering!

Comments

ohoilett (author)2017-03-18

Would that be too much solder paste for an SSOP or QFN package?

Mjtrinihobby (author)2017-01-13

This old electrical engineer just learned something new!

TwistOneUp (author)2017-01-10

Wonderful, and thanks NemesisC!

Most of the smd device datasheets I have seen state a max of 250C in the reflow oven settings. I have a reflow workstation with adjustable airflow and temp settings, and have to mount a SOT-23 on a DIP breakout adapter. I'm wondering if I need to go up to 370C, so I'll be trying 250C. I think the trick will be to set the airflow at just enough to melt the solder but not strong enough to push the breakout board out of my panavise.

I would also like to mod a toaster oven, but do not have a source for used ovens, so if anyone has an article on modding current-ish model toaster ovens, I would really appreciate it. Tia!

NemesisC (author)TwistOneUp2017-01-11

Definitely I'm mostly very impatient and want instant melting -however not always a good idea! Yes having a low airflow helps a lot expecially when the component begins sliding around. Have you tried to use silly putty/tape to hold down the component? I've been told it works wonders

christherock23 (author)2016-11-14

Awesome instructable! Personally i prefer the skillet method but this is mostly due to the fact that ive been doing it forever, i do all my PCBs 100% SMD. A cheap skillet on the stove sure beats trying to solder 50 components by hand lol.

NemesisC (author)christherock232016-11-15

Thank you Chris! Would you recommend any nice quality affordable skillets?

christherock23 (author)NemesisC2016-11-15

To be honest just about any skillet will work. Im using an old one we had in the house (my mom burned chicken in it so she didnt want to cook with it anymore) the one im using has teflon which is great because the boards are easy to slide around. If you can find one at a thrift store that has a pretty good surface i would buy that and experiment with it. The hot plate method is great with parts containing a lot of plastic. Hot air tends to melt the plastic on things such as usb ports really easy. Hope this helps :)

mdeudon (author)2016-11-15

Good ;-)

luckyluc (author)2016-11-10

True, for this type of component it is not worth using this method.

NemesisC (author)luckyluc2016-11-10

To save time it is.

p_leriche (author)NemesisC2016-11-15

Excellent Instructable - thank you NemesisC! But for only very occasional use the hot air solder station isn't easy to justify. I recently hand soldered a few SOIC-8 chips and a SOIC 20pin device to breakout boards. The key is to stick the boards to the bench with Blu-tac and rest your wrist on the bench to steady your hand, and use a sufficiently powerful magnifier, a 1mm iron bit and flux pen. Flushed with success I then threw caution to the winds and attempted 3 SSOP 8 pin devices, and succeeded! But it's quite tricky not to get solder bridges between the pads, though not too hard to clean them up with solder wick. I wrote it up at https://therestartproject.org/wiki/Surface_mount_soldering - take a look if you like.

throbscottle (author)2016-11-13

I tried this technique a few years ago using a heat gun and it was a disaster! The solder wouldn't melt whilst it seemed the chip was getting excessively hot.

However you have inspired me to try again. I'll try making longer pads like you have, maybe that is what makes the difference.

NemesisC (author)throbscottle2016-11-14

Definitely give it another go!

diy_bloke (author)2016-11-14

thanks for the write up. Would that be a hot air tool, or a hot hair tool (check the bold print under the top picture). For a moment I thought you'd be telling to use a blowdryer :-)

NemesisC (author)diy_bloke2016-11-14

thank you for the catch! Added the fix :)

Eric Brouwer made it! (author)2016-11-08

Good Instructable. Thank you. I use the same equipment and method for the items I build.

sauvee (author)Eric Brouwer2016-11-10

Hi, DIY PCB didn't have solder mask. Do you apply solder paste to the copper pad only? Or as this instructables, you can apply solder paste between the copper pad and the board will repel the solder paste to shrink and harden onto the copper pad?

Eric Brouwer (author)sauvee2016-11-10

You can use the method as shown with the SOIC soldering. It works great when you use the hot air station. As the solder melts, it will flow towards the pads, and actually pull the component nicely into place as well.

When using a fine-tipped soldering iron, I only apply the solder paste to each of the individual pads.

sauvee (author)Eric Brouwer2016-11-12

Thanks for your answer. I will try it next time a do a PCB.

NemesisC (author)Eric Brouwer2016-11-10

Nice board! Are those some DIY Servo cable extensions they look great!

Eric Brouwer (author)NemesisC2016-11-10

Thanks. They are actually all R/C switches using the PC board as shown.

HamishA1 (author)2016-11-10

are there better solder paste dispensers? it looked really slow and problematic with you dispensing the solder paste. anyone got some links to better ones?

Eric Brouwer (author)HamishA12016-11-10

I use a Magnum MD100 dispencer. works great for me.

NemesisC (author)HamishA12016-11-10

The reason why the GIF shows a shaky hand is because I was recording and applying the paste at the same time since I don't have a tripod. I kept checking if the shot was in frame to make sure people could see the process. I have only used the Chip Quik solder paste which comes with 2 different dispensers. Maybe Maker Paste would be useful it comes with a wider dispenser sold at Adafruit, Pimoroni and ICbreakout

RaymondR6 (author)2016-11-10

This is a very useful guide, but why "a hot hair tool"? Even if it were a "hair dryer" the temperature will never reach the melting point of solder.

cobusmalan (author)RaymondR62016-11-10

The hot air tool in question there is used for desoldering and soldering, it definitely reaches the correct temperature. I even use a normal heat gun in a very controlled fashion for the same purpose. You are right about a hairdryer though.

LeanDean (author)2016-11-10

Thanks for a good demonstration. Even though the videos don't play on my old trash can PC, there is enough to encourage me to try the smaller devices that I have been avoiding because me old hands are not nearly as good at fine soldering as they used to be.

Aaaecm (author)2016-11-10

This is an awesome Instructable. Many thanks. The videos were very helpful.

NemesisC (author)Aaaecm2016-11-10

Thank you so much! I'm very glad the videos helped I will do more instructables with videos then .

PhilTilson (author)2016-11-10

I'm not sure I would agree with the last two comments. You can just
about get away with it for SOIC-8 chips, if you have a VERY fine
soldering tip and a steady hand, but when it comes down to SSOPs, where
the inter-lead spacing is barely half a millimetre, I'd go for the
solder paste solution every time!

The only thing I would say is to
be very careful with the hot air gun. It's easy to go WAY over the
maximum temperature of the chip with those. I still prefer the oven
approach. I modified a £17 toaster oven very easily and can now make
perfect SMD boards virtually every time.

Syco54645 (author)PhilTilson2016-11-10

I drag solder AM29f033 all the time. Not had any issues yet.

Pentagrid (author)PhilTilson2016-11-10

Hi PhilTilson, have you documented the process you used to modify your toaster oven please? I clicked on your name but no 'ibles came up.

Best, John:)

PhilTilson (author)Pentagrid2016-11-10

No John, I've read lots of 'ibles, but never created one yet!

Maybe it's time....

Phil

NemesisC (author)PhilTilson2016-11-10

Thanks Phil !

With any SMD soldering I prefer to use solder paste because it's just so much faster than using a soldering iron.

Thank for the tip! I always like to read the chip's data sheet to check the max temperature ratings. As well as using the low air flow control of my hot air tool.

Nice, I've used my oven as well : how did you modify yours? Would like some tips to have a reliable SMD oven !

DeanP2 (author)2016-11-10

I have added a small surface mount audio filter to my amateur radio station but need to replace it. I failed using a conventional soldering process my second time, but now I think I could get one built after all. Thanks!

NemesisC (author)DeanP22016-11-10

Happy to help Dean would love to see pictures of your build!

ve3vxy (author)2016-11-10

did you heat and melt the solderpaste to the board first and then place the component? I have always placed the component on the paste and then applied heat.

NemesisC (author)ve3vxy2016-11-10

Just like you do, I placed the component on the paste and then applied heat.

TonyB172 (author)2016-11-10

The Blue is actually Soldermask. The Silkscreen is the white writing on the blue.

Nice Instructable!

NemesisC (author)TonyB1722016-11-10

Thank you for the catch Tony! Added the fix :)

logan.byrne.77 (author)2016-11-09

This actually helps me since I came into a large handful of smds from TI.

NemesisC (author)logan.byrne.772016-11-10

I'm glad I could help!

kcraske (author)2016-11-08

Tutorials such as this are really good considering the increasing number of smd components. Especially as some components are now only available as smd.

NemesisC (author)kcraske2016-11-08

Thank you!

I agree plus smd soldering is always seen as such a scary process but it's really fun!

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