Common wire-to-board, wire-to-wire connectors, and crimp tools

Contents

Introduction

As someone who builds a lot of electrical things, one of the perhaps most unexciting yet fundamental subject areas is connectors. The range of connectors available and in-use today is trully astonishing. Big sellers like Digi-key/Farnell/Mouser literally have tens of thousands of product lines in their connectors category!

With so many different types of connectors available, it’s often difficult to know what to buy, especially when you’re buying for general use and/or personal stock. On this page I’ll cover some of the most common connectors in use today, and detail crimping/tooling considerations.

Every connector system ever conceived has its own official crimp tool, in most cases the cost of these is over and above what any hobbyist could and would want to pay for a crimp tool.

I personally own many of the official tools but for cost reasons don’t necessarily recommend them.

Engineer PA-09 and PA-21
Engineer PA-09 and PA-21

For the past 5 years this page has been focused on comparisons with the above tools. Note that I do not recommend buying these. They are expensive, poorly finished, causing contacts to stick in the jaw, and the scissor type action makes it difficult to get sufficient force on the conductor part.

My recommended budget tools

My preferred budget tools: IWISS SN-2549 and Engineer PAD-11
  • IWISS SN-2549. A 4 die tool for smaller contacts. It’s good for most medium sized power connector families on this page i.e. Microfit, Mini-Fit Jr, E.I., KK .156, Mate-n-Lok, .187 FASTON, JST PH. It has a cleanly machined jaw, so contacts won’t get stuck in it. It crimps the conductor and insulation in a single action, with the ratchet double hinge mechanism providing good force on the conductor part. It tends to apply too much force to the insulation part, but one cannot have it all on a budget.
  • IWISS SN-58B. Another good 4 die tool from IWISS, however all significantly larger than the SN-2549. Recommended if you work with larger contacts.
  • Engineer PAD-11. Unlike the PA-09/21 its jaw is cleanly machined, allowing easy removal of contacts after crimping. It is a little pricey but definitely wins for crimping smaller contacts i.e. PH, XH, Picoblade, SL, KK 100 etc.
  • IWISS IWS-2820M. A copy of the Engineer PAD-11. Not as well made but for the significantly lower price, it could be forgiven.

For those with a little more to spend

Hozan P-707

Several readers have written to me about this tool over the years – it’s generally well spoken of. I recently obtained a sample myself and can confirm that it’s a good option for those happy to spend a bit more. It tends to cost around $70-80 and has to be ordered from Japan.

It has two features which many generic tools lack:

  • Lots of conductor crimping force. Its compound hinge amplifies the crimping force, meaning you can have as much as you like, you can even crush the contact into two if you so desire. Single hinge tools like the Engineer PA-XX models cannot achieve this unless one has an extremely strong grip, or the tool is compressed in a vice.
  • It has two ‘O’ shaped crimping dies, something that is rarely seen on generic tools. This means it does good ‘DuPont’ crimps. More about that here.
  • The above two features are combined in a tool which crimps conductor and insulation separately. This gets around another common problem with generic tools where these are combined, in that one may be under or over crimped. You can crimp both separately to whatever extent you require.

It’s not a clear-cut winner however as it is more effort to use than the IWISS ratcheting tools and gets less consistent results, owing to the fact that crimping force is controlled by your hand.

IWISS have added an exact copy of this tool to their catalogue – IWS-1442L. Don’t expect it to be made to the same standard as the Hozan. Personally I would prefer they spent their efforts improving the mediocre results of their own designed crimp tools, rather than copying others.

Do your own research too. There are thousands of generic crimp tools out there. I cannot test them all.

What differences can I expect using original tools versus generic tools?

These are four main differences:

  • Single action: All original tools allow insertion of the contact and crimping in one go. Generic tools will often require the insulation and wire crimp to be performed as separate actions
  • Correct crimping force: When using generic tools, it can often be difficult to get sufficient crimping force, especially when crimping thin / small gauge wire into contacts . It is also equally easy to over crimp contacts, damaging the wire in the process.
  • Locator: All original tools have a ‘locator’ which holds the contacts in place during crimping, this means that your crimps are perfect every time. Using generic tools, it can be frustrating trying to line the contacts up correctly.
  • Insulation crimp accuracy: Original tools are designed to not piece the insulation, whereas generic tools do most of the time. This means that terminations subject to continual mechanical stress are going to last a lot longer.
  • Cost: Original tools are all extremely expensive.  Unless like me you’re happy to prowl eBay looking for deals on second hand original tools, expect to be paying hundreds to over a thousand dollars (USD) / £ (GBP) for an original tool, only to have it work on a single connector family! To rub additional salt into your wounded wallet, it’s not uncommon to find that the connector manufacturer has a different tool for every single wire size, each costing $500+

What’s wrong with just soldering contacts?

Before I get started, let’s cover this one briefly with a simple diagram:

Correctly crimped terminal
Correctly crimped contact

When crimped properly, the strands remain individual even upon entering the insulation crimp, making the chances of strands breaking low.

Soldered terminal
Soldered contact

When soldering, there is a very high chance that the solder will wick up the conductor, beyond the insulation crimp, making it very vulnerable to mechanical damage. In this situation, it only takes a small amount of movement to start snapping the strands at the invisible weak point.

Soldering doesn’t have any disadvantage in electrical terms, only mechanical. That make this method non-viable for production use; except under very controlled conditions with connectors that are designed for soldering. This having been said, I would recommend soldering in scenarios where connectors are carrying significant current, and the manufacturer tool is unavailable (see below).

Below is an interesting graphic from TE, from this video. On the left a cross section of a “gas tight” crimp, typical from a manufacturer original tool. The graphic on the right is the typical result of an off-brand tool. It’s important to put this into context however – gas tight crimps are only needed where contacts are used near their current rating, are expected to last a very long time, and/or the consequences of failure are serious.

Source: TE Connectivity

Branded vs no-brand contacts

Back when I first started using crimp connectors, almost everything I built made use of cheap no-brand contacts with no particular care as to what they were plated with (not that it was ever specified anyway). Why waste money on name brand contacts when no-brand contacts work just fine?

Fast forward a few years, and I find that some of that equipment I built 3-5 years ago begins to malfunction. The problem was that I had mated contacts from two different eBay sellers with differing plating. The dissimilar metals in use corroded over the years ending in failure.

Attempts to save a few quid back then have now resulted in hours of profanities as all of those connectors have had to be re-crimped with name brand gold contacts.

If you are not on a tight budget, and building something that has to be reliable, and last – go straight for manufacturer original gold plated contacts . If buying Molex: 0.38µm “Selective” plated contacts are good enough (unless your creation is a life support system, or going to the moon).

Alternatively, if you don’t want to stump up for gold plated contacts – Tin plated contacts from known brands i.e. Molex / TE/ Amphenol / JST will last a lot longer than no-brand contacts.

Brass vs Phosphor bronze contacts

Phosphor bronze and brass are both alloys of copper, however with different ingredients. Phosphor bronze contacts are generally regarded as superior as they are harder and retain their tension for significantly longer. Smaller brass contacts may need to be re-tensioned after 5-10 mating cycles. If a contacts material is not specified (i.e. it’s a cheap no-brand type) assume it’s brass.

There are other exotic materials used in contacts i.e. beryllium alloy however these tend to only be found in very expensive contacts (for example genuine Mini-PV).

Mini-PV – Amphenol, M20 – Harwin (and other “DuPont” clones)

Mini-PV housings, and a variety of contact sizes and plating options

These (and look-a-likes) are the most commonly used type by hobbyists. I have a separate page with a lot of detail relating to these.

Common JST Connectors

Another range of common types used by hobbyists. There are quite a few to cover. I’ve detailed them on a separate page.

KK 254 / KK .100 (Molex)

Various KK.254 and compatible components. The design of the polarisation on Molex types is inferior to that of other manufacturers, with two small protrusions at the base of the housing, instead of the usual ribs which run at least half of the length of the housing. Because of this, smaller 2 and 3 position connectors skew to one side when the wire is pulled on. The one exception is the special type with fan style polarisation.

Connectors resembling these are produced by many manufacturers, most of whom are anonymous factories in mainland China, whose product is sold under a plethora of different brand names. For the most part, headers and housings mate and latch fairly well across brands.

As explained in the caption above, Molex/TE’s housing design is different to most no-name types of this connector. I’ve not been able to identify a well-known manufacturer who produces these with the longer (superior) polarising ribs.

Despite my dislike of Molex’s polarisation design – I don’t use the more common no-brand types anymore as several years ago I had a bunch of them fail after 18 months due to corrosion on the mating surface. I have since replaced all them with Molex Gold plated types which have now been running for 4 years without incident.

Example part numbers (Molex)

Numbers in bold can be changed to order connectors with a different number of positions.

Contact AWG 22-30 (Tin plated)08-50-0114
Contact AWG 22-30 (Selective gold plated, mating surface only)08-55-0102
Housing 3 position22-01-2035
Housing 4 position (PC fan style polarisation)47054-1000
Header 3 position (Tin)22-27-2031
Header 3 position (Gold plated)22-29-2031
Header 4 position (Tin plated, PC fan style polarisation)47053-1000
Header right angle 3 position (Gold plated)22-12-4032
Header right angle 3 position (Tin plated)22-05-7038
Hand crimp tool AWG 22-3063811-8200
Molex KK100 crimp tool
Molex KK100 crimp tool (mfg’d by Pressmaster Sweden)