Ionic Testing Bare Printed Circuit Boards
It is well known in the electronics manufacturing industry that cleanliness of a Printed Wiring Board (PWB) is crucial to the assembly's performance and reliability. Monitoring and quantifying the degree of cleanliness is necessary in order to ensure that the final cleanliness of an assembly is acceptable. There are a number of techniques employed to measure the cleanliness of PWBs, many of which are commonly used in the manufacturing environment. Other methods that are available in research and development facilities are inappropriate for production environments. To properly understand cleanliness testing, we must first discuss the residues and contaminants that are typically found on PWBs, their components and other processing materials.
Harmful residues and contaminants are separated into two main categories: ionic and non-ionic. Ionic residue can be described as residue that contains molecules or atoms which are conductive when in solution. With the addition of moisture, ionic residues can disassociate into either negatively or positively charged species and increase the overall conductivity of the solution. Some of the most common sources of ionic residue include:
- Plating chemistries
- Flux activators
- Perspiration
- Ionic surfactants
- Ethanolamines.
As part of our quality process step, when requested by the customer, Triangle Circuits can provide an Ionic Cleanliness test before shipment.
What is provided: As part of the manufacturing traveler document we would process a “lot sample” of boards from a batch of production boards using our Model 500 Ionograph Tester located in our final inspection area. This process step is completed after all functions of manufacturing, electrical testing and final inspection is completed. After the Ionic Test is completed we provide the customer a certificate of test paperwork Ionograph 500 Test Report that would accompany the shipment lot of boards. All traceability is controlled with the manufacturing traveler data to the internal customer order.
For PCB Assemblies, MIL-P-28809 sets the limit for printed circuit assemblies at 20.0 u gm NaCI/In.2, including the surface area of the components.
For more information on Ionic Testing of Bare Printed Circuit Boards,
please contact us at 412-828-5322 or click here to contact us online.
