How can you tell if solder is bad?

the solder should be shiny after it hardens. If it has gone bad it will stand around on street corners, smoking cigarettes and making weird sucking sounds at female passersby. Another sign of a bad solder joint is if the solder is dull after it hardens, this is what happens with a “cold” joint.

Is it OK to use old solder?

Presumably, one reason for a stated expiration date is that the flux becomes less active over time as it interacts with the solder metal. But in our personal experience, this kind of solder seems to generally work just fine, even many years past its nominal shelf life.

What is the shelf life of solder?

Solder Preforms and Ribbon

Stored properly, performs can have a shelf life of up to five years. Since lead-containing alloys are more prone to oxidation, they should be used within six months of the manufacture date.

Why does my solder not stick?

Flux removes oxidation from metals, and it’s crucial because solder won’t stick to oxidized metals, and metals oxidize very quickly at soldering temperatures. 3. Not enough heat: A 15 Watt iron is fine for small chips, but any larger connectors or wire bigger than 16 gauge will cause problems.

How do you test for good solder?

What Constitutes Good SMT Solder Joint Quality?

  1. component pin and footprint pad are aligned;
  2. pad area is completely covered with solder;
  3. component pin area in contact with pad is completely covered with solder;
  4. no excess solder covers component;
  5. solder joint is smooth;
  6. solder joint does not contain voids; and.

Why does my solder bubble?

It is caused by flux boiling through the solder you’re laying down. That’s why you notice it more on the second side of a project – by then you have sealed off the other side, it can’t splatter out the back. As you may have guessed, the best thing you can do to limit this is use less flux.

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How long can solder paste sit out?

Go out as many hours as you feel necessary. Usually we don’t do it beyond four hours; although, in the early days of solder paste testing we’ve gone out as much as 24 hours.

Can solder joints fail?

Mechanical overstress failures occur when a solder joint experiences excessive loading during a mechanical event — such as a shock, drop, in-circuit testing, board depanelization, connector insertion or PCBA insertion. Overstress failures can be difficult to prevent because they are often difficult to predict.

Is solder conductive of electricity?

The electrical conductivity of soft and hard solders is considerably less than that of copper, varying with composition between approximately 9 percent and 13 percent for soft solders and 20 percent and 40 percent for silver solders.

Can I solder without flux?

Yes, you can solder without flux. While it is helpful in the process of soldering as the flux helps break down the oxides on the metal, it is not needed. Also, most solder nowadays come with a rosin core which does the job of flux helping breaking down oxides.

How do you fix a oxidized soldering iron tip?

If a tip does become oxidized, flush it several times with a rosin-activated, flux-cored solder. That should remove the oxides unless you have allowed the oxidation to build up excessively. After cleaning, cover the tip surface with a thick coating of solder.

Why does my soldering iron not melt solder?

Solder has a very low melting point (compared to other metals/alloys). Even a weak 40W iron should melt it almost instantly. If it’s not melting the solder, then the iron is not hot enough or even working. Try poking the tip through a piece of paper.

What makes a good solder connection?

Good solder joints

A good solder joint will have a shiny finish to it, and it should not have too much solder. Typically the contour of the solder around the joint should be slightly concave.

Where is my soldering cold joint?

Cold solder joints can be detected by visual checking or using a magnifying glass. Primarily, a cold solder joint could look dull, whitish, and convex, or deformed, which is very different from a proper solder joint. Another way to detect a cold solder joint is by using a Multimeter.

How do you test a soldered wire?

Set your multimeter to Ohms of resistance (looks like a drunk, upside-down “U”). Place the leads from the multimeter together and they should say O and you’re ready to go. Place one lead on each side of the solder joint, Ohms of resistance! Rob is right.

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What is the Tiffany method?

He developed a line of lamps – and later, jewelry – using the old technique of adhering copper foil to glass and soldering the glass together into gorgeous designs. These days, the “Tiffany technique” mostly refers to soft-soldered jewelry that’s made with lead-free, silver-bearing solders.

Why does my solder have black spots?

Those dark splotches are leftovers from the resin-based flux. No-clean fluxes are often made out of water-soluble resins (vs rosin) and during heating, most of it will evaporate away.

Why does my solder look dirty?

When soldering zinc, hold your iron on the zinc a little longer than you would on lead. When soldering zinc to lead, touch the zinc came first to heat it a bit before touching the lead too. The zinc might turn dark and almost look scorched, but this will clean up.

Can I use expired flux?

Flux is one of the three things you need to make a solder joint. You need heat, metal and flux. Don’t take any chances. If it is expired, don’t use it.

What happens if you don’t refrigerate solder paste?

Jars should be stored right side up. Does solder paste require refrigeration? Recommended storage temperature for solder paste is between 40°F and 50°F (4°C to 10°C). Storage at temperatures above refrigeration will reduce shelf life and voids the guarantee.

How long can solder paste sit before reflow?

Solder paste must be kept in a controlled environment for it to remain useful for a long period of time. It should be stored in a cool place and will last approximately 20 weeks at 39 to 50°F (4 to 10°C) in the refrigerator. At 68°F (20°C), solder paste’s useful lifetime is considerably reduced, to around 6 weeks.

What makes soldering bad solder?

Overheated solder joints can result from the soldering iron temperature being set too high, or result from solder failing to flow, possibly due to the surface of the pad or lead already having a layer of oxide, preventing sufficient heat transfer and therefore leaving you heating the joint for too long.

What causes solder to crack?

Solder cracks occur when heat stress is applied to a solder joint due to the difference in the thermal coefficients of the MLCC and PCB, in an environment in which changes between high temperatures and low temperatures are repeated.

Can you have too much flux?

Flux is an acid base and when excess flux is left on the exterior of the pipe after soldering it will promote premature corrosion of the pipe wall. Properly when soldering all joints should be immediately wiped with a clean damp lint free rag to remove the excess solder while the pipe is still warm.

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Will solder carry current?

When soldering, the metal parts that are to be bonded are heated quickly, then flux and solder are added to the surfaces. When the molten solder cools, it hardens and creates a nearly unbreakable bond that will conduct electricity.

Is silver solder a good conductor?


It has higher electrical conductivity than other soft solders and a melting point approximately 40°C higher than either 60/40, 63/37 or LMP alloys.

What is the melting temperature of solder?

Soft solder typically has a melting point range of 90 to 450 °C (190 to 840 °F; 360 to 720 K), and is commonly used in electronics, plumbing, and sheet metal work. Alloys that melt between 180 and 190 °C (360 and 370 °F; 450 and 460 K) are the most commonly used.

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Hi, I'm Nam Sun-Hi. My first name means: "One with a joyful demeanor." I'm a Korean student and author at I spend all my time either writing or studying. I love learning new things, and I think that's why I enjoy writing so much - it's a way of learning more about the world around me.