From J-STD-001E:
3.9 Soldering Tools and EquipmentTools and equipment shall [DID2D3] be selected, used and maintained such that nodamage or degradation that would be detrimental to the designedfunction of parts orassemblies would result from theiruse. Soldering irons,equipment, and systems shall [DID2D3] be chosen and employed to provide temperature control andisolation from electrical overstress or ESD (see 4.1). A tool used to cut leads shall not [DID2D3] impart shockthat damagesa componentlead seal or internal connection. SeeAppendix A for guidelines on tool selectionand maintenance.
From J-STD-001ES (for Hi-reliability Space requirements) Section3.9 states:
Soldering Tools andEquipment Tools and equipment shall be selected, used, and maintained such thatnodamage or degradation thatwould be detrimental to the designed function of parts or assemblies resultsfromtheir use. Soldering irons, equipment,and systems shall be chosen and employed to provide temperature controland isolation from electricaloverstress or ESO (see 4.1), and shall be calibrated in accordance with ISO 17025or ANSUNCSL-Z540- 1-1994. A tool used tocut leads shall not impart shock thatdamagas a component leadseal or internal connection. See Appendix A for guidelines on tool selectionand maintenance.
Here is Appendix A2:
A-2 BENCHTOP AND HAND SOLDERINGSYSTEMSSelection criteria of bench-top and hand soldering systemsinclude:- A. Soldering systems areselected for their capacity to heat theconnection area rapidly and maintain sufficient solderingtemperature range at the connection throughout the solderingoperation.
- B. Temperaturecontrolled solderingequipment (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 mayalso be used.
- C. Operator selected or rated temperatures ofsoldering systems at idle/standby should bewithin +/- 15C [+/- 27F] of actualmeasured tip temperature.
- D. Resistance between the tip of solderingsystems and the workstation common point ground should notexceed 5 ohms.Heated element and tips are measured when at theirnormal operating temperature.Note: Current limiting soldering equipment manufactured to EN000 15-1: 1992 may not meetthis requirement.
- E. AC and DC current leakage from heated tip toground should not create deleterious effectson equipment/components.
- F. Tip transient voltagesgenerated by the soldering equipmentshould not exceed 2V peak (Zio" Q).Note: Current limiting soldering equipment manufactured to EN00015-1:1992 may not meet this requirement.The appropriate guidelines of this section also apply to nonconventional bench-top soldering equipment;including equipmentwhich utilizes conductive, convective, parallel gap resistance, shorted bar resistance, hot gas, infrared,laser powered devices,or thennal transfer solderingtechniques. Toolsused are to be maintained suchthat no detrimental damage results from theiruse. Tools and equipment are to be cleanprior to use and should be kept clean and free of dirt, grease,flux, oil and otherforeign matterduring use. The heat source is not tocause damage to the printed board or components.
Most companies that I work with test their irons for resistancefrom tip to ground (5 ohms maximum), temperature ( +- 9 degrees fortip-controlled stations, and +- 15 degrees for adjustable stations), andvoltage (no more than 20 mV) each MONTH. A reaction plan (including containment and review) shouldbe documented for irons failing test.
For solder stations that use screw-on tips or loose tips held inplace with a screw-on barrel, the operators should break the tips out, lightlysand the seat or bottom of the tip, and re-assemble before turning the station on at the beginning oftheir shift. This breaks the oxide layer that can build up from dailyuse, and reduces the tip-to-ground resistance and voltage buildup that canresult from an oxide-insulated tip. It also means you generally have no containmentand review activity to perform as a result of a monthly tiptest 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.
|
