At times, there’s a need for electrical connections to become solid, however, temporary. Or, it could be subjected to much vibration in order to undo what was done; or, you will have to break or make many connections all at once throughout the board.
For these cases, these usual combinations of cables, plugs, and sockets might not be appropriate. This is why we may consider making use of spring loaded pins or spring loaded pin connectors.
Properties of the Spring Loaded Pins
For our connections, the spring loaded pins could bring these properties:
- With pressure, you can create or break multiple connections at about the same period and across a very large area. These are useful for the testing jigs like bed of nails which have to connect, test, and disconnect quickly.
- Also, they need a soldered component on just one of both boards. Most times, this board is one which is not mass-produced. Furthermore, its mating side will only require a minim pad at just one place. This helps in saving space, cost, as well as the routing area.
- If it is chosen and well-designed, they could work in environments having vibration
- These compressed connections could be vertically compact; boards could be stacked close to themselves
- With springs, you have height flexibility, which is useful in cases where there are staggered board stacks or uneven boards.
It is very useful; however, anyone who has made an attempt to spec the spring loaded pins knows fully well that there are lots of combinations to select from. These include material, tip geometry, diameter, height, plating, material, height, housing, force, and more.
In this article, we’ll be focusing more on those features, which relates to compatibility with manufacturing and placement of automated components.
Get it Right
First, you need to know that electrical connections must be reliable and robust. Also, spring loaded pins have to be placed at an appropriate angle. In addition, they have to be properly aligned with the contact’s center found on the opposite side, and not buckle, bend, or become unaligned with pressure applied.
There is a need for the contact pad found opposite the pin to be large and flat enough to be able to account for the alignment vibrations and mismatches, and plated in a way that this contact does not degrade with time and use.
As we know, the placement of the component could be done making use of the automated pick and place machine or manually done. The pick and place is usually cheaper for the high component boards. Therefore, ideally, we try to select components that work well with the process. Whenever we refer to the spring loaded pins, there’s a need to have caps that sit on the top of every discrete pin or on just a subset of these pins in ‘housed’ connector arrays. The pick and place head grabs this cap for placement.
Also, they need to come in a specific packaging that works well with the pick & place machines. These include tape, tube, tray, reel, etc. When delivered in ‘bulk’ or ‘loose’, the assembler would have to manually place them into the pick and place feeder or solder them by hand, and end up charging you for additional work done.
Addressing Stability and Alignment
Here, we will be addressing stability and alignment. Below are some properties to take note of.
Through hole or surface mount
The through hole for the spring loaded pins is at times referred to as a ‘tail’ that offers a solid solder stability and joint.
Connector or single array
The single pins, most especially those having no housing can easily experience as well as stability problems during assembly and use respectively.
The connector array’s configuration
One row might experience the misalignment whenever it is soldered. Therefore, a reliable choice would be the 2 x 2 array and larger. Therefore, when you have to choose between the 2 x 3 and 1 x 6 configurations, the former is better.
Proportion of the base area to the length
When a pin is longer, the base area would be smaller. With this, there is a greater chance for unreliability and misalignment. Defining its ‘length’ is difficult. However, you should pay attention to this, most especially the surface mount pins.
With respect to stability and alignment, the most appropriate spring loaded pin is through hole, with its ‘tail’ as short as possible, as well as arranged in a larger configuration or housed 2 by 2. If you wish to use the surface-mount or long pin, most especially the single pins, then you have to first consult the assembly house to know if they encountered any problems given their equipment and process.
Lastly, make sure you work with instructions of the manufacturer regarding assembly, as well as reach out to them when choosing the most appropriate variant for your applications. This helps you make the best decision especially when there are lots of parameters and options available.
What are the Applications of the Spring Loaded Pins?
Board to Board
Spring loaded pins are a requirement for board to board connections between at least two boards. You can stack these boards on themselves using the spring movement. This helps to accommodate misaligned boards, tolerance stack-ups, as well as errors found in co-planarity and parallelism.
You can accomplish this in different ways making use of the spring-loaded pin. Whether these boards are perpendicular or parallel, horizontal or vertical, our company always provides a solution. Also, our company offers spring pins having a very low profile off the circuit board so as to accommodate the limited space present in the vertical or z axis.
Device/Battery Charging
The spring loaded pins serve as the best solution for the charging of batteries in the docking of handheld devices and portable instruments for power and data transfer reasons. You can easily integrate them into systems having numerous options present in terms of the spring force, travel, and height.
Contact is usually made with the plunger tip of the spring pin. This spring pin permits blind mating, as well as misalignment whenever you are placing the device or battery into the cradle. This makes it a great selection for this application.
Blind Mate
There are applications whereby aligning the receptacle combination/traditional pin could be difficult as a result of restricted visibility present in the designs. This is usually termed blind mate. Receptacle/pin misalignment during an engagement could result in missing or poor connections, damaged contacts, and bent or broken pins. An appropriate solution to this is a strong pin because there is no need for an insertion.
These spring pin connections are created with plunger tips having contact with conductive surfaces. Usually, the mating surfaces are larger compared to spring pin plungers that eliminates any concerns regarding potential damage and alignment to components.
Test Points
The spring loaded pins are very useful as the test points present on boards that require verification after the final assembly. Also, they are appropriate for the high-volume automated test environments offering reliability and easy access.
Cable Termination
Spring loaded pins with the wire crimp termination or solder cup features could be utilized in cable or wire harness applications. The termination of the cable into the spring loaded pin and press-fitting or over-molding the spring pin in the plastic housing permits users to create cable terminated connectors with benefits of the spring loaded contact as its point of connection. Again, this is great for quick connects and blind mating applications that are typically related to the cable connectors.
Our spring pins’ superior performance when under vibration and shock conditions offer sustained reliability with time. This makes them perfect for jostling and handling of cables.
What Our Spring Loaded Circuits Offer
At times, we know that it is impossible to source or use the appropriate or ideal pin. However, we can accommodate all variants, but this would come with an added cost (for re-reeling, custom jigs, hand placement, etc.) If you doubt anything, we advise that you contact us early so as to discuss ways in which we handle your components’ choices to ensure the cheap and effective handling of your board assembly.
Also, take note that pins which need plated holes having a diameter of 0.45mm or less need important considerations. During the manufacturing process, when the plated hole is not seen as the plated hole of the components and has a completed diameter smaller or equal than the certain size, we treat it as a via. Also, for vias, we permit ‘negative tolerance’ in contrast with the component holes that indicates that the holes might be smaller compared to the specified size.
A very safe way of preventing the treatment of the component plated holes as vias is to reduce the threshold for the classification of the via.
Conclusion
In summary, spring loaded pins offer great benefits. With pressure, you can create or break multiple connections at about the same period and across a very large area. These are useful for the testing jigs like bed of nails which have to connect, test, and disconnect quickly.
