Questions tagged [reflow]

Reflow soldering is a type of soldering where solder paste is applied to the pads, after which the components are placed on top and then it is baked in an oven.

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19
votes
4answers
12k views

Why does solder not conduct sometimes?

I was reflowing and a 2K 603 resistor partially tombstoned. There was solder connecting the lead to the pad, yet my DMM showed an open. When I heated both ends and the resistor came down and contacted ...
17
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6answers
3k views

SMT solder reflow temperature profile

I have read many website and forums about DIY reflow ovens for SMT soldering. I have also seen many solder profiles as specified by the solder manufacturers, component manufacturers, and other self-...
14
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2answers
20k views

Why and when to use reflow soldering?

I was looking at an instructable and they suggested using "reflow soldering" for a certain section. "Reflow" wasn't a concept i was familiar with, so I did some Googling... I got a basic description ...
14
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3answers
4k views

Is it safe to repeat reflow soldering?

I have a board that is partially reflow soldered with a QFN and a couple of 0603 capacitors and resistors. I wanted to test functionality with this stage before I go ahead and place the other ...
13
votes
2answers
7k views

DIY BGA soldering feasability

BGA seems to be somewhat of a showstopper for the diy community, especially with the newer more powerful parts being almost exclusively bga. I know it can be done with the skillet/toaster oven method,...
12
votes
3answers
5k views

Soldering heatsink pad on bottom of IC

I am attempting to make a board for the tlc5951 24-channel led driver to drive an 8x8 rgb led array. I have made what I think is a good eagle library for the sop-38 package, but I am not sure what to ...
12
votes
2answers
28k views

Any drawbacks to “low temp” lead-free solder paste?

I am about to try my first "reflow skillet" soldering job, and as I look at the available types of solder paste I see there are lead-free pastes with much lower melting temperatures than others. For ...
10
votes
2answers
1k views

Will “hot plate” reflow soldering work without a solder resist coating?

With a successful through-hole design under my belt I am now ready to try fabricating a board that uses surface-mount components. I have been reading about this, and have gathered that the DIY crowd ...
10
votes
1answer
461 views

Can you program a surface mount IC with flash memory and then reflow solder them?

I know that many chips, such as the ATMEGA328P-AU list flash storage lifetimes at certain temperatures, but they usually cap out at 100° C. I know that, ideally, one should include leads on their ...
9
votes
8answers
2k views

Assembly of PCBs containing a mix of SMT and thru-hole parts?

I have a batch of beta PCBs which we have to assemble in our lab. We have an APS manual pick-and-place machine and a tabletop reflow oven so I thought assembly tomorrow would be easy and straight ...
9
votes
3answers
2k views

Solder paste not wetting at all

I have an issue with solder paste, I would like to know its origin so I can fix the problem and solder by components properly. I use a lead free Sn42/Bi57.6/Ag0.4 solder paste, manufactured by ...
9
votes
3answers
1k views

Reflow at home or solder manually?

I'm considering doing DIY SMT Reflow for production of my Super OSD project. An overview of the component count: Resistors: ~50 x 0603; precision 0.1% resistors as well as 1% and 5% components ...
9
votes
1answer
2k views

Soldering BGA components DIY

If I understood correctly, current BGA components contain solder balls under the package. Do I still need additional solder paste to put on the board, or the amount of solder on the component contacts ...
8
votes
1answer
999 views

Solder paste stencil application

I am trying to do reflow soldering with a stencil for the first time. I have done some reflow soldering before, but every time I manually applied the paste using a small syringe + needle. These ...
8
votes
2answers
727 views

Why do the Sparkfun and Adafruit Eagle libraries use smaller footprints than the manufacturer's recommended land pattern?

I'm comparing two datasheets from Micron and Infineon to the Sparkfun and Adafruit footprints for TSSOP-28 Both the footprints use an SMD pad size of 1.0x0.3 mm, while the manufacturers recommend ...
7
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5answers
2k views

SMD solder now or later?

I'm soldering up some boards with smd parts, using a hot plate to reflow, and I'm (inevitably) realizing that I got some of the wrong parts. Now, is it better to leave the boards with smd components ...
7
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3answers
4k views

Is it advisable to use lead-free PCB and solder paste on a first SMD assembly job?

I am sending my first PCB design to Sunstone for manufacture and I need to decide whether to order the board finish lead-free. All of the components are lead-free, and I have not decided on solder ...
7
votes
2answers
4k views

Components on both sides of the board with reflow

Is it possible to place components on both sides of the board if I'm doing DIY toaster-oven style reflow soldering? I would think that doing the reflow twice (for the other side) might overheat the ...
7
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2answers
2k views

DIY Reflow soldering

This is related to this question. I'm trying to get started with a DIY reflow soldering station intended for my personal use. I'm planning on starting small and improving the system as time goes on (...
7
votes
1answer
1k views

What causes components to “jump” during reflow soldering?

I've been using a hot plate technique (with a PID controller / thermocouple / SSR setup) to get into making SMD boards. I had an interesting experience earlier today, and I was hoping some more ...
6
votes
1answer
508 views

Rule of thumb for surface tension when placing components on the secondary side of a board

I've been working on my first multi-layer PCB design, and have been placing a variety of components on the secondary side of the board (mostly decoupling capacitors and QFN ICs). However, some of ...
6
votes
2answers
1k views

How well do reflowed connectors self align?

I am thinking of using some Hirose DF40 PCB stacking connectors to stack together a bunch of PCBs. Each pair of PCBs would be connected by two connectors for mechanical stability. These connectors do ...
6
votes
1answer
255 views

Non-wet open solder fault on the same ball of two different devices of the same part?

Sophisticated PCBA, with a DM6446 using two 16 bits DDR2 devices to implement a 32 bit memory space. On some boards, we see a stuck bit on either bit 24 or bit 8, which map to the same BGA ball (C8) ...
5
votes
3answers
19k views

Questions about reflowing solder on a motherboard

One of my laptop's DIMMs is dead and working with less than my usual 8GB of RAM is brutal. Multiple sources suggest reflowing the board. I quite frequently tinker with/hack my electronics, but I've ...
5
votes
1answer
777 views

Do SMD resistors have to be reflowed black side up, or is black side down okay?

I reflow my own boards in a toaster oven. When I drop my resistors off the paper tape, I always flip them over to black side up before I place them. Should I bother if it doesn't really matter?
5
votes
3answers
830 views

Insulating a via during reflow?

I have a PCB that I'm sending off for assembly, which includes going through a reflow oven. The last batch had a problem because the solder mask on some PCBs does not completely insulate a via that ...
5
votes
4answers
359 views

Temperature sensor recommendation

I am builing a homemade reflow oven, but I cant find a good and cheap temperature sensor that can survive the temperatures necessary for reflow (~250ºC or 482ºF). Does anyone have a recommendation? I ...
5
votes
1answer
3k views

Hot air lead-free BGA reflow

I'm experimenting with trying to reflow a 0.8mm BGA myself for prototypes/repairs. I've solved the main problem: alignment. I've used my 3D printer to print custom board guides that align on large ...
5
votes
2answers
487 views

Potential pitfalls/caveats for developing a stencil for solder reflow

I'm developing a project that requires ICs that are in a QFN package, some have a slug on the bottom of the IC. Since these are QFNs, I'm not interested in hand soldering these; so I'm leaning toward ...
5
votes
1answer
499 views

Soldering pins underneath a connector

I wish to solder this type of HDMI connector (Datasheet) to matching pads on a PCB: So half the pins are protruding out into the clear, and that row is easy to solder. But just behind that row, as ...
4
votes
5answers
6k views

Using a home oven for solder paste

I'm doing a project and I have a PCB which needs surface mount components attaching to it. One component has already been attached, and I have some 138deg solder paste in a syringe. This is possibly ...
4
votes
2answers
2k views

Have I cooked my caps?

Recently been calibrating my solder reflow oven to work with a higher temperature solder paste. Had a few boards come out that were slightly over done. At 250 degrees Celsius I noticed that the silk ...
4
votes
3answers
1k views

What's a good plastic for self-cutting solder paste stencils on a laser?

I've tried making my own solder paste stencil using 4 mil polyester (for overhead projection slides) on a 45W Epilog laser cutter at the local TechShop maker space. I could not "cut" the stencil ...
4
votes
1answer
90 views

Small DFN chips come out twisted from the oven

This is a 2 x 2 mm chip with 12 no lead contact points. Half of the time I get it out of the reflow oven, it's twisted like in the image below. I am using a stencil in order to lay the paste down and ...
4
votes
1answer
109 views

When I rework an SMD capacitor or resistor, it will sometimes stick to the soldering tip. Does this high temp then destroy it?

When I rework 0402 capacitors, then often stick to the tip of the soldering iron. My iron is set at 350. I then discard the cap because I am worried the sustained temp for a few seconds has destroyed ...
4
votes
1answer
1k views

Are thermal reliefs on SMD pads beneficial when reflow soldering?

I know that thermal reliefs have benefits when hand-soldering through-hole components. For some high-frequency or high-current components, I understand why it's a good idea not to use thermal reliefs....
4
votes
1answer
66 views

How to solder large smd components on a PCB with 2oz copper

I’ve got a large inductor that needs to be soldered to my board. The pads are hidden underneath the component so hand soldering is not an option. The data sheet says to reflow at 260c for 40 seconds ...
4
votes
1answer
353 views

How to bake MSL components for DIY reflow?

I'm intending to reflow solder some components from Analog Devices. Since they are an LFCSP package, hand-soldering is not possible. They arrived with a warning that they are moisture sensitive (MSL3) ...
4
votes
1answer
196 views

Do all/most SOIC chips whitstand the 235 degrees C for reflow soldering?

I want to try reflow soldering for several projects (small scale). For some of the components (e.g., resistors and ceramic capacitors), the datasheet does give specific information about maximum ...
3
votes
5answers
2k views

Why not reflow a PCB before placing parts?

A standard reflow method for low-volume assembly is: Method A Apply solder paste (using stencil or syringe) Hand-place parts (using vacuum pickup pen or tweezers) Oven reflow - But what happens if ...
3
votes
2answers
8k views

how to solve the solder joints not shiny?

I have met a problem, need your help. I had used Sn62Pb32Ag2 (liquid temperature is 179℃)solder paste to solder components for many years,solder joints always are shiny. but recently,when I used it to ...
3
votes
2answers
487 views

Are PTC/resettable fuses really moisture senstive?

I recently bought some 0805 Multicomp PTC/resettable fuses from Farnell. They were MC36213 (500mA) and MC36206 (200mA). I plan to use these in product which may exist in a high humidity (~80-90%) ...
3
votes
4answers
534 views

Do any SMT components require hand soldering due to heat limitations?

It has been claimed on another board that some SMT components cannot be used in an automated production line (i.e. reflow or wave soldering) because they cannot withstand the heat/temperature. Hand ...
3
votes
2answers
2k views

GPU reflow soldering profile

I've had my ENGTX480/2DI/1536MD5 GPU for 3 and half years now. Over the past 2 months it started causing trouble. At first, it started seldom displaying big zones with weird color, but simply ...
3
votes
3answers
140 views

SMD solder failure due to probing? How to solve it?

I was visually inspecting a board that had functional problems, and I have noticed a strange pattern in the pads surrounding the IC. Upon electrical inspection, there are two pads that are shorted ...
3
votes
1answer
2k views

PCB Reflow in oven, will solder melt before VRM's, caps etc get damaged?

From Wikipedia: Alloys commonly used for electrical soldering are 60/40 Sn-Pb, which melts at 188 °C (370 °F), and 63/37 Sn-Pb used principally in electrical/electronic work. 63/37 is a eutectic ...
3
votes
1answer
121 views

LEDs lighting up while being baked inside a reflow oven

This is a board with 80 3535 LEDs on it just after completing the reflow cycle in my home-made reflow oven. Why are the bottom corner LEDs lit up? Rather, how is this happening?
3
votes
2answers
351 views

Low Melting Point solder paste reflow profile adviced

I've found a low temp solder paste with a melting point of 140°C. I want to use it with some SMD parts. I've looked for some reflow profiles and didn't found nothing with this low melting point. Can ...
2
votes
2answers
1k views

In order to avoid solder bridges during reflow, What is the minimum pad-to-pad spacing?

With regard to DFM, I am wondering if there is no risk of solder bridge during reflow as long as there is a soldermask web between the pads? Soldermask clearance(2 mils*2) + soldermask web(4 mils) = 8 ...
2
votes
3answers
598 views

Question after my first attempt with reflow soldering

I have a couple of questions, plus I'd invite any comments/feedback/suggestions to improve my results. I used solder paste Chipquik SMD291AX10 (Sn 63 / Pb 37) on the pads and also flux (Chipquik ...