After small-scale manufacturing of a new product in the lab, it must be transferred for manufacturing on a larger scale. High volume manufacturing can either be done by the original company that produced the product, or it can be taken-over by a contract manufacturer. During this process, techniques and procedures usually have to be adjusted in response to the larger volume and/or speed of manufacturing, often resulting in issues that have not been previously anticipated.
This was the case during the manufacturing of Transcutaneous Electrical Nerve Stimulation (TENS) devices by EPRT in Simi Valley, California. As production volumes increased, problems with both yield and cleaning were encountered. In addition, since the TENS device is a medical product, certification and process validation were required. They contacted the contract manufacturer Digicom Electronics, which was able to improve yield and assist in the development, manufacture, testing and process validation of the product.
The TENS device produces a precisely measured current which, when applied to the skin’s surface, causes the nerve to overload and inhibits it from generating pain impulses. It is, therefore, useful in the treatment of lower back pain. However, since the device uses a very low current (less than one millionth of an amp), any contaminants can easily cause the device to malfunction. Thus, exact process control is required when building the product.
Issues with Yield
Want to publish your own articles on DistilINFO Publications?
Send us an email, we will get in touch with you.
When ERPT initiated larger-scale volume manufacturing, they identified a yield of only 80-85%. After assembling the modules, they were tested and pass. The epoxy step was then completed which involved encapsulation; but after this, the devices were retested and subsequently failed.
Digicom engineers investigated the situation. They found that, during the epoxy cure process, heat had damaged the components and caused shrinkage which resulted in mechanical stress. The engineers suggested that the relay was being damaged by the shrinkage.
It was determined that, in particular, the epoxy cure caused the miniature relay to become deformed and drag on the relay cover. The engineering team solved this problem by covering the relay with a small box, which prevented deformation and improved device performance.
Cleaning Issues
During volume manufacturing, issues associated with device cleanliness also tend to arise. In the case of the TENS manufacturing, it was found that residue formed on the circuit board from the solder flux was causing contamination and increasing risk of electrical failure.
Digicom use their advanced cleaning and analysis techniques to ensure that even the smallest levels of contaminant were removed, thus improving the function of the circuit board. The process used devices that measured high impedance and low currents in order to detect contamination at the picoamp range.
Certification and Process Validation
Process validation of a product ensures that a process is able to reliably generate a specification-meeting product. It is an important component in the design, prototyping, and manufacturing process and one that, if done correctly, can save on time, money and resources.
In addition, regulatory bodies, such as the FDA, may request process validation. The FDA’s Quality System Regulation, 21 CFR part 820, requires process validation to be performed by medical device manufacturers when the process has not been verified by a subsequent examination.
In 2003, Digicom published their ISO 13845:2003 medical devices quality and quality system regulation 21 CFR (Code of Federal Regulations) 820. These validations established a commitment to the quality of medical devices and stated the requirements for the design and production of medical devices to ensure they meet the requirements of both customers and regulations.
By having the manufacturing process validated by a company that already has ISO 13845:2003, such as Digicom, certain procedures and requirements are more likely to be met, so certification is less labor intensive, and approvals from regulatory bodies will proceed more easily.
Date: July 2, 2018
Source: AZOmaterials