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July 18, 2012

Inspection and Maintenance for Soldering Irons

Is there a standard procedure covering recommended periodic inspection and maintenance of hand held soldering irons?

E.W.

Experts Comments

From J-STD-001E:
3.9 Soldering Tools and Equipment Tools and equipment shall [DID2D3] be selected, used and maintained such that no damage or degradation that would be detrimental to the designed function of parts or assemblies would result from their use. Soldering irons, equipment, and systems shall [DID2D3] be chosen and employed to provide temperature control and isolation from electrical overstress or ESD (see 4.1). A tool used to cut leads shall not [DID2D3] impart shock that damages a component lead seal or internal connection. See Appendix A for guidelines on tool selection and maintenance.  

From J-STD-001ES (for Hi-reliability Space requirements) Section 3.9 states:
Soldering Tools and Equipment Tools and equipment shall be selected, used, and maintained such that no damage or degradation that would be detrimental to the designed function of parts or assemblies results from their use. Soldering irons, equipment, and systems shall be chosen and employed to provide temperature control and isolation from electrical overstress or ESO (see 4.1), and shall be calibrated in accordance with ISO 17025 or ANSUNCSL-Z540- 1-1994. A tool used to cut leads shall not impart shock that damagas a component lead seal or internal connection. See Appendix A for guidelines on tool selection and maintenance.

Here is Appendix A2:
A-2 BENCHTOP AND HAND SOLDERING SYSTEMS Selection criteria of bench-top and hand soldering systems include:
  • A. Soldering systems are selected for their capacity to heat the connection area rapidly and maintain sufficient soldering temperature range at the connection throughout the soldering operation.
  • B. Temperature controlled soldering equipment (at rest) should be controlled within +/- S'C [+/- 9'F] of the idle tip temperature. Constant output (steady output) tools in compliance with A-2a, d, e, & f may also be used.
  • C. Operator selected or rated temperatures of soldering systems at idle/standby should be within +/- 15C [+/- 27F] of actual measured tip temperature.
  • D. Resistance between the tip of soldering systems and the workstation common point ground should not exceed 5 ohms. Heated element and tips are measured when at their normal operating temperature. Note: Current limiting soldering equipment manufactured to EN 000 15-1: 1992 may not meet this requirement.
  • E. AC and DC current leakage from heated tip to ground should not create deleterious effects on equipment/components.
  • F. Tip transient voltages generated by the soldering equipment should not exceed 2V peak (Zio " Q). Note: Current limiting soldering equipment manufactured to EN 00015-1:1992 may not meet this requirement. The appropriate guidelines of this section also apply to nonconventional bench-top soldering equipment; including equipment which utilizes conductive, convective, parallel gap resistance, shorted bar resistance, hot gas, infrared, laser powered devices, or thennal transfer soldering techniques. Tools used are to be maintained such that no detrimental damage results from their use. Tools and equipment are to be clean prior to use and should be kept clean and free of dirt, grease, flux, oil and other foreign matter during use. The heat source is not to cause damage to the printed board or components.
Most companies that I work with test their irons for resistance from tip to ground (5 ohms maximum), temperature ( +- 9 degrees for tip-controlled stations, and +- 15 degrees for adjustable stations), and voltage (no more than 20 mV) each MONTH. A reaction plan (including containment and review) should be documented for irons failing test.

For solder stations that use screw-on tips or loose tips held in place with a screw-on barrel, the operators should break the tips out, lightly sand the seat or bottom of the tip, and re-assemble before turning the station on at the beginning of their shift. This breaks the oxide layer that can build up from daily use, and reduces the tip-to-ground resistance and voltage buildup that can result from an oxide-insulated tip. It also means you generally have no containment and review activity to perform as a result of a monthly tip test failure.
Richard D. Stadem
Advanced Engineer/Scientist
General Dynamics
Richard D. Stadem is an advanced engineer/scientist for General Dynamics and is also a consulting engineer for other companies. He has 38 years of engineering experience having worked for Honeywell, ADC, Pemstar (now Benchmark), Analog Technologies, and General Dynamics.
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