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16. Printed Circuit Boards

16.1 General PC Board Requirements

PC boards manufactured for Caltrans equipment shall conform to the following minimum requirements:

  1. Material: FR4 1 oz. Copper
  2. Copper plate conductor surfaces to thickness required by current draw
  3. Solder coat or tin-lead plate followed by reflow of all metallic surfaces (trace edges may be excluded) on two sided PC boards all through holes to be plated through.
  4. Solder mask both sides of board
  5. Copper etch or stamp with permanent ink the applicable revision letter
  6. Silkscreen required to show component designator from schematic on component side.
  7. Wire wrap shall not be used on printed circuit boards.
  8. Printed circuit boards exposed to the outside environment, high humidity or condensing moisture shall have conformal coating.

16.2 Electronic Equipment Assembly Requirements

  1. Refer to latest version of referenced standards.
  2. Equipment assemblies, subassemblies, printed wiring assemblies, terminal board assemblies, electronic modules, etc., shall be Class 2 or better as defined in J-STD-001 "Requirements for Soldered Electrical and Electronic Assemblies".
  3. Component mounting shall be in accordance with IPC-CM-770 "Component Mounting Guidelines for Printed Boards" or IPC-SM-780 "Component Packaging and Interconnecting with Emphasis on Surface Mounting", Class 2 or better.
  4. Printed boards shall be in accordance with IPC-A-600 "Acceptability of Printed Boards" class 2 or better.
  5. Assembly shall be in accordance with ANSI/IPC-A-610 "Acceptability of Electronic Assemblies" and J-STD-001B. Class 2 or better.
  6. When conformal coating is required, coating material shall conform to IPC-CC-830 "Qualification and Performance of Electrical Insulating Compound for Printed Wiring Assemblies". Class A or better.
  7. Solder mask shall be in accordance with IPC-SM-840, Qualification and Performance of Permanent Solder Mask, Class T.

16.3 Design/Process Checklist for Vehicle Electronics (SAE J1938)

The purpose of SAE J1938 is a checklist to provide a reminder and guideline of the different aspects of the electronic system design for vehicles.

16.4 Environmental Practices for Electronics Design (SAE J1211)

16.4.1 Applicability

Caltrans vehicles, coupes, sedans, hard top vehicles, and pickup trucks.

SAE J1211 states that as a recommended practice "the use of this report is entirely voluntary" (operative term is "should"). For use on Caltrans vehicles, this report is mandatory (operative term is "shall"). Refer to the latest version of SAE J1211.

16.4.2 Vendor Responsibility

Electronics shall be tested per SAE J1211 or by other applicable standards (e.g., IPC, Mil-Standard, etc.) that meet or exceed the requirements of SAE J1211. It is the responsibility of the supplier to provide test documentation and photographs certifying that the production electronics sold to Caltrans comply with these minimum conditions. If Caltrans duplicates these tests and the unit does not operate as required then the unit fails the test. If there are questions, please call Caltrans, Division of Equipment, Quality Assurance Branch at 916-227-9709.

16.4.3 Environmental Considerations

The data presented in SAE J1211, "Environmental Factors and Test Methods", describes major characteristics of the expected environment that have an impact on the performance and reliability of automotive electronic systems. These environmental characteristics are:

  • Temperature
  • Humidity
  • Salt Spray Atmosphere
  • Immersion and Splash (Water, Chemicals, and Oils)
  • Pressure Washing
  • Dust, Sand and Gravel Bombardment
  • Altitude
  • Mechanical Vibration
  • Mechanical Shock
  • General Electrical Environment
  • Steady State Electrical Characteristics
  • Transient, Noise, and Electrostatic Characteristics
  • Electromagnetic Compatibility / Electromagnetic Interference

16.4.4 Location Within Vehicle

Environmental extremes are considered separately for the following locations inside and outside of vehicles and equipment:

  • Underhood
  • Interior
  • Chassis
  • Exterior

16.4.5 Temperature Cycle

Temperature testing shall meet the requirements of SAE J1211 Section 4.1.3. An 8 hour temperature cycle shall be used (Figure 2B). Temperature range shall be as required by location in the vehicle. The unit shall be on, running, and shall not fail during the test.

16.4.6 Thermal Shock

Thermal shock testing shall meet the requirements of SAE J1211 Section 4.1.3. Temperature range shall be as required by location in the vehicle. The unit shall be on, running, and shall not fail during the test.

16.4.7 Humidity

Testing shall meet the requirements of SAE J1211 Section 4.2.2. The unit shall be on, running, and shall not fail during the test. Test period shall be 8 hours (Figure 3B)

16.4.8 Salt Spray Atmosphere

Testing shall meet the requirements of SAE J1211 Section 4.3.2. The unit shall be on, running, and shall not fail during the test.

16.4.9 Immersion and Splash (Water, Chemicals, and Oils)

Splash testing shall meet the requirements of SAE J1211 Section 4.4.3. The immersion test is not required. Actual environmental chemicals to be tested are engine oils and additives, washer solvent, gasoline, diesel fuel, alcohol, anti-freeze water mixture, soap and detergents, steam, battery acid, water, snow and salt water.

16.4.10 Steam Cleaning and Pressure Washing

Pressure wash testing shall meet the requirements of SAE J1455 Section 4.5.3. The steam test is not required. The unit shall be on, running, and shall not fail during the test.

16.4.11 Dust, Sand, and Gravel Bombardment

Dust and sand testing shall meet the requirements of SAE J1211 Section 4.5.3. The alternate test method is acceptable. The unit shall be on, running, and shall not fail during the test. Gravel testing shall be performed as described in SAE J1455 Section 4.5.3

16.4.12 Altitude

Testing shall meet the requirements of SAE J1211 Section 4.16.3. The unit shall be on, running, and shall not fail during the test.

16.4.13 Mechanical Vibration

Vibration testing shall be guided by SAE J1211 Section 4.7. The unit shall be on, running, and shall not fail during the test.

An additional vibration test is the road test per SAE J1211 Section 4.7.3. Operate the vehicle over a non-paved road with rocks, ruts, pot holes, etc. (complex surfaces) for at least 100 miles in less than 8 hours. The unit shall be on, running, and shall not fail during the test.

16.4.14 Mechanical Shock (Operational)

Testing shall be guided by SAE J1455 Section 4.8, Sections 4.8.1.3 and 4.8.2.4. The unit shall be on, running, and shall not fail during the test.

16.4.15 General Automobile Electrical Environment

Testing shall meet the requirements of SAE J1211 Sections 4.9 and 4.10. The unit shall be on, running, and shall not fail during the test.

The units shall be tested from Table 2 Automotive (12 V system) voltage Regulation Characteristics. Table 3 – Automotive Transient Voltage Characteristics. Table 4 – Summary of Automotive Electrical Continuous Noise Characteristics.

16.4.16 EMI

  1. For electrical noise, EMC, EMI, etc, refer to SAE J1113-13. The unit shall be on, running, and shall not fail during the test.
  2. Electromagnetic immunity shall meet the requirements of EN 50082, and meet the light industrial standard.
  3. Electromagnetic emissions shall meet class B requirements of EN 55022.
  4. Devices that emit radio frequency (RF) energy are subject to the rules and regulations of the Federal Communications Commission (FCC) 47 CFR Parts 2 and 15.

16.5 Environmental Practices for Electronics Design (SAE J1455)

16.5.1 Applicability

Caltrans heavy-duty trucks and equipment other than sedans, vans and light trucks. Also see 16.5.5 Exterior Electronic Equipment.

SAE J1455 states that as a recommended practice "the use of this report is entirely voluntary" (operative term is "should"). For use on Caltrans vehicles, this report is mandatory (operative term is "shall"). Refer to the latest version of SAE J1455.

16.5.2 Vendor Responsibility

Electronics shall be tested per SAE J1455 or by other applicable standards (e.g., IPC, Mil-Standard, etc.) that meet or exceed the requirements of SAE J1455. Caltrans suppliers shall provide test documentation and photographs certifying that the electronics sold to Caltrans comply with these minimum conditions. If Caltrans duplicates these tests and the unit does not operate as required then the unit fails the test. If there are questions, please call Caltrans, Division of Equipment, Engineering Design at 916-227-9604 for clarification.

16.5.3 Environmental Considerations

The data presented in SAE J1455 "Environmental Data and Test Methods", describes characteristics of the expected environment that have an impact on the performance and reliability of truck electronic systems. These environmental characteristics are:

  • Temperature
  • Humidity
  • Salt Spray Atmosphere
  • Immersion and Splash (Water, Chemicals, and Oils)
  • Pressure Washing
  • Fungus
  • Dust, Sand and Gravel Bombardment
  • Altitude
  • Mechanical Vibration
  • Mechanical Shock
  • General Electrical Environment
  • Steady State Electrical Characteristics
  • Transient, Noise, and Electrostatic Characteristics
  • Electromagnetic Compatibility / Electromagnetic Interference

16.5.4 Location Within Vehicle

Environmental extremes are considered separately for the following locations inside and outside of vehicles and equipment:

  • Underhood
  • Interior Cab
  • Interior (Aft of Cab)
  • Chassis
  • Exterior of Cab

16.5.5 Exterior Electronic Equipment

Exterior mounted electrical or electronic equipment shall use the guidelines listed in SAE J1455 Table 14 – "Exterior – Environmental Data" for design considerations and test criteria. This applies to trailer-mounted or truck-mounted arrowboard signs, trailer or truck-mounted portable changeable message signs (PCMS) and any other exterior mounted electrical equipment.

16.5.6 Temperature Cycle

Temperature testing shall meet the requirements of SAE J1455 Section 4.1.3. An 8 hour temperature cycle shall be used (Figure 2B). Temperature range shall be as required by location in the vehicle. The unit shall be on, running, and shall not fail during the test.

16.5.7 Thermal Shock

Thermal shock testing shall meet the requirements of SAE J1455 Section 4.1.3.2. Temperature range shall be as required by location in the vehicle. The unit shall be on, running, and shall not fail during the test.

16.5.8 Humidity

Testing shall meet the requirements of SAE J1455 Section 4.2.3. The unit shall be on, running, and shall not fail during the test. Test period shall be 8 hours (Figure 4a)

16.5.9 Salt Spray Atmosphere

Testing shall meet the requirements of SAE J1455 Section 4.3.3. The unit shall be on, running, and shall not fail during the test.

16.5.10 Immersion and Splash (Water, Chemicals, and Oils)

Splash testing shall meet the requirements of SAE J1455 Section 4.4.3. The immersion test is not required. Actual environmental chemicals to be tested are engine oils and additives, washer solvent, gasoline, diesel fuel, alcohol, anti-freeze water mixture, soap and detergents, steam, battery acid, water, snow and salt water.

16.5.11 Steam Cleaning and Pressure Washing

Pressure wash testing shall meet the requirements of SAE J1455 Section 4.5.3. The steam test is not required. The unit shall be on, running, and shall not fail during the test.

16.5.12 Fungus

Testing shall meet the requirements of SAE J1455 Section 4.6.3.

16.5.13 Dust, Sand, and Gravel Bombardment

Dust and sand testing shall meet the requirements of SAE J1455 Section 4.7.3. The alternate test method is acceptable. The unit shall be on, running, and shall not fail during the test.

Gravel testing shall be performed as described in SAE J1455 Section 4.7.3

16.5.14 Altitude

Testing shall meet the requirements of SAE J1455 Section 4.8.3. The unit shall be on, running, and shall not fail during the test.

16.5.15 Mechanical Vibration

Vibration testing shall be guided by SAE J1455 Section 4.9. Any of three different test methods may be specified. Where applicable, the specified Power Spectral Density (PSD) shall be used and housing shall be hard-mounted to the vibration source. Unit shall be functionally tested after appropriate stop points in the test (such as changing axis). Units shall be inspected and functionally tested at the completion of the test.

16.5.15.1 Swept Sine Vibration Tests

The first vibration testing shall be performed per SAE J1455 Section 4.9.4.1. Test severity depends upon intended location on a vehicle per Figure A1 in Appendix A. Test duration shall be 180 minutes for each axis. The unit shall be on, running, and shall not fail during the test.

16.5.15.2 Random Vibration Testing

The second vibration test method shall follow the random vibration testing described in SAE J1455 Section 4.9.4.2. The testing shall consist of 3-hour duration in each orthogonal axis at the following power spectral densities:

10 Hz

0.015 g²/Hz

40 Hz

0.0015 g²/Hz

500 Hz

0.00015 g²/Hz

The unit shall be on, running, and shall not fail during the test.

16.5.15.3 Road Test

The third vibration test , SAE J1455 Section 4.9.4.3, is to operate the vehicle over a non-paved road with rocks, ruts, pot holes, etc. (complex surfaces) for at least 100 miles in less than 8 hours. The unit shall be on, running, and shall not fail during the test.

16.5.16 Mechanical Shock (Operational)

Testing shall be guided by SAE J1455 Section 4.10, sections 4.10.2.3 and 4.10.3.4. The unit shall be on, running, and shall not fail during the test.

16.5.17 General Heavy-Duty Truck Electrical Environment

Testing shall meet the requirements of SAE J1455 Section 4.11. The unit shall be on, running, and shall not fail during the test.

The units shall be tested from Table 3A Truck/Tractor (12 V system) voltage Regulation Characteristics. Section 4.11.2 Table 4A – Typical 12 V Vehicle Transient Voltage Characteristics.

16.5.18 EMI

  1. For electrical noise, EMC, EMI, etc, refer to SAE J1113-13. The unit shall be on, running, and shall not fail during the test.
  2. Electromagnetic immunity shall meet the requirements of EN 50082, and meet the light industrial standard.
  3. Electromagnetic emissions shall meet class B requirements of EN 55022.
  4. Devices that emit radio frequency (RF) energy are subject to the rules and regulations of the Federal Communications Commission (FCC) 47 CFR Parts 2 and 15.