Get under the skin of terminal blocks

The bill-of-materials lists terminal blocks. Suppliers have been sought. Samples are beginning to arrive. On the surface, the competitive products look similar but their prices vary wildly. So, are all terminal blocks created equally. In a conversation with Camden Electronics Andy Hatter, the answer was definitely no. Andy explained: Camden has specialised in PCB terminal blocks since its inception, focussing on quality, competitively priced products which are predominantly European manufactured. The company is involved in all aspects of development, design, inspection and sales.

In terms of product performance and reliability, Camden specifies virgin polymers during the manufacturing process, with material recycling limited to no more than 25 per cent. If the polymers are recycled more than 25 per cent, which can be the case for cheaper products, the customer can end up with a brittle component. In reality, recycled materials can reach 80 per cent so customers are advised to clarify this with the component manufacturer or distributor. On this same point, heavy recycling can also influence flammability rating, again worth checking.

If components are manufactured in regions with high utility costs, there is a temptation to reduce injection mould temperature and cycle time which, in turn, increases the likelihood of producing a brittle connector. Such products are susceptible to cracking when terminal screws are tightened.

On the subject of terminal block screws, European manufactured parts tend to use mild or hardened steel, while cheaper designs will use a soft steel. Hardly surprisingly, when such screws are tightened there is a danger the thread will strip. Soft steel screws are also associated with thin plating which can lead to corrosion problems.

The reason that terminal block quality is such an issue is that the connector is potentially the only component an end customer will interact with when installing or using a new electronic product. So, if the connector fails, it is likely that the customer will reject the whole product and refuse to purchase that brand again.
Ignoring detailed quality issues during the purchasing process can also lead to increased product manufacturing costs. For example, most European manufactured terminal blocks will use a brass/copper/
nickel/tin plating process. Cheaper designs may skip the copper and/or nickel. This removes an important bonding layer and, if the tin is lost during the soldering process, solderability issues can hamper production. On an even finer point, buyers should determine whether the tin plating is matt or bright. Bright might look nicer but is, in fact, an inferior finish. It oxidises faster leading to potential shelf-life and solderability problems. This can have serious consequences for UK manufacturers if products have to be removed from highly automated production lines and reworked by hand.

RoHS has been a positive driving force for Camden. The legislation has not prevented us introducing many new products over the past eighteen months. If anything, provided manufacturers are being diligent about their RoHS compliancy, it is actually a golden opportunity to revisit their product design and further enhance their product features. For example, at Camden the RoHS compliance process drove us to take a detailed look at our materials and suppliers. The net result is that we have actually been able to reduce our material costs.

As can be seen, saving a few pence on a terminal block by accepting inferior product quality can have significant negative effects, ranging from increased manufacturing costs to customer rejections of faulty goods. Dont assume that connector blocks that look alike are alike. Its a case of buyer beware.