Ask the Experts
August 21, 2018
Automatic Insertion Causing Plated Hole Damage
During the automatic insertion of 2 pin components, and after clinching the pins, we encounter a small deformation and/or sometimes small crack in the land or wall of the plated hole. We need to use a mechanical clinching method per the customer request. These 2 pin components must sit flat on the PCB, with no tilt. What can we do to reduce or eliminate the plated hole damage. What is the criteria for acceptability of cracks and deformation of the plated hole wall?
Expert Panel Responses
Interesting question. Sometimes I believe the customer has to beeducated and this may be the case in this situation. The condition caused bythe clinching of the leads is damaging the product and will cause catastrophicfailures in the product.
All the IPC specifications mention in the clinchingsection that large pins or tempered leads are not to be clinched due to thispotential plated through hole damage occurring from the clinching operation. Ifthe connector needs to be flat to the board, perhaps an alternative methodshould be used to secure the component to the laminate material, such as anadhesive.
Alternative methods such as manually soldering the component in placewould produce a more reliable connection than continuing trying to meet therequirements of the customer as defined by their documentation.
IPC-A-610 Rev E, page 7-38 explicitly states that tempered leadsshall not be terminated with a full clinch configuration, and evenpartial clinch with such large leads will cause damage to the plated throughhole barrel.
IPC-A-600 Rev H, page 99, section 3.3.6 discusses plating cracksand they are not allow for any class of products.
This is a designissue that must be addressed by the user and supplier as this condition is notacceptable under any circumstance.
Vice President, Technical Director
At EPTAC Corporation, Mr. Lambert oversees content of course offerings, IPC Certification programs and provides customers with expert consultation in electronics manufacturing, including RoHS/WEEE and lead free issues. Leo is also the IPC General Chairman for the Assembly/Joining Process Committee.
Intrusive reflowcould solve the problem. Board would need to be redesigned for non-pressfit holes.
Vice President Technology
For over 18 years, Dr. Coleman has been the vice president of technology for Photo Stencil, working closely with customers to understand their printing requirements. His efforts have resulted in several new stencil products.
PTHis likely to get damaged if the part lead is stiff and not clinchable easily.Hence it is necessary to check if the lead diameter and / or material of thelead suitable for clinching. Second a proper clinching tool is to be used thatgives acceptable clinch.
It is also necessary to check the thickness of thecopper and solder plating at the corner of the PCB and it should be greaterthan 1 micron minimum. From the picture it is evident that the component issitting flat on the PCB and the constraint point on the Component side of thelead is not available to provide acceptable clinch. This is a clearnon-clinchable type of mounting.
Astra Microwave Products, Hyderabad, AP India
Holds Degree in Engineering, started off as Scientist/Engineer in ISRO (Indian Space Research Organization) in Quality Assurance of Space hardware Electronics Production. Worked in the area of Parts, Material and Process; DPA, FA and Process Qualification for space and ground hardware. Later moved into Private sector and worked in the area of Quality Management Systems & ISO 9001 certification. Currently hold a position as Head-Quality in RF/Microwave Product manufacturing for Defense and Aerospace segment.
After seeing the images, it is pretty obvious that this designis not suitable for clinching. There are selective soldering methods includinghand placing (if feasible) that will ensure that a correct/conforming solderjoint is achieved and the clinch operation is not necessary. Design change iscostly but a slight change in the process requirements can fix the problem.
Recommendations can be made to fix this issues and the final decisionwill be in your customer's court.
Engineering and Operations Management
Georgian Simion is an independent consultant with 20+ years in electronics manufacturing engineering and operations.
Contact me at firstname.lastname@example.org.