Triad Magnetics Frequently Asked Questions
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Question: Are Triad Transformers board washable?
Standard Transformers which Triad Magnetics offer come primarily in two configurations; open construction and potted. The open construction types are either wound on a bobbin, directly onto a torroid or rod core, or wound on a paper tube with paper sections between each layer of windings. A ferrite core or laminations (usually made of steel) are then introduced and the finished item is dipped in varnish impregnation. Potted transformers follow a similar process path with the additional step of epoxy potting compound being introduced around the transformer.
The materials that make up a transformer are all quite resistant to most commonly used solvents in a cleaning operation. The most vulnerable component is the impregnation varnish used. These varnishes are formulated to be thinned with benzene derivative solvents such as xylene or toluene. For the potted transformers, the benzene derivative solvents are also recommended to be avoided, although the attack will be much slower and therefore probably render no damage for short exposures (room temperature for less than 2 minutes).
If an aqueous clean is used (often consisting of a 10% to 70% solution of Isopropyl Alcohol and water), it is recommended that an oven bake at least 60°C be included for at least 30 minutes after immersion. The reason for this is that the open construction type transformers have the potential for harboring the water within the windings which will cause oxidation over time.
Question: What is Triad recommended Hand-Soldering Procedure?
General Recommendations for Hand Soldering Thru-Hole Transformers
In an effort to minimize the amount of lead that ends up in our land-fills and our water tables, almost all environmentally conscious companies have moved away from solder containing lead to the more eco-friendly lead-free type solders. Triad Magnetics is one of those companies, in that since 2005, all of the products we produce are RoHS compliant. This includes the absence of lead in the solder on our pins, lugs, and tinned leads.
The soldering methods for lead-free solder differ from the traditional Sn60/Pb 40 and Sn 63/Pb 37 used in the past. The most significant difference is the need to use a higher temperature on your soldering iron. This paper is published to highlight some of the basic principles for soldering pins with lead-free solder to printed circuit boards.
Solder Iron Tip Selection:
As is the case for all soldering, the proper tip for the size of the pin and pad is important for a good conformal joint.
The tip width should be at least 2/3 the width of the pad, but no larger than the full width of the pad.
Typically, the solder wire used will have a flux core. Best results will be experienced when the diameter of the solder wire is appropriate for the pad as well. Solder wire approximately equal to the diameter of the pin is commonly specified.
Solder Temperatures and Touch Times:
The pictures below were taken to demonstrate the resulting solder joints for various touch time and solder tip temperature combinations. The soldering iron used for the demonstration was a Weller WD-1 (which has a rating of 85W of power.)
A tip temperature of 600°F held to the solder joint for 3 to 4 seconds normally produces a good conformal joint on both sides of the board.
A tip temperature of 600°F for just 1 or 2 seconds produced an acceptable solder joint on the bottom of the board, but did not allow enough time for the solder to flow to the other side of the board.
A tip temperature of 500°F even at 5 to 6 seconds does not properly bring lead-free solder to the liquidous state. The result is that no whetting of the pin occurs and no solder flows to the other side of the board.
A tip temperature of 650°F for 3 seconds causes the solder to flow too freely, often leaving an excess build up of solder on the top side of the board. Higher temperatures also creates a longer cooling time, so the risk of a disturbed solder joint is increased.
Triad factories use a soldering iron tip temperature of 600°F and a touch time of 3 to 4 seconds, touching both the pad and the pin. We have found this to be an optimum point for most applications where we are soldering thru-hole transformers to boards. Your factory floor conditions may vary in terms of equipment used, environment, and type of Lead-free solder used. Your process may need to be adjusted in terms of touch time and temperature in order for you to achieve the desired results for your solder joints.