How often can you raise a Eurocircuits PCB to lead-free soldering temperatures?

By Dirk Stans – Eurocircuits and Geert Willems – Center for Electronics Design & Manufacturing, imec


[1] PBA Design-for-Manufacturing Guideline EDM-D-001: PCB Specification, imec-cEDM, July 2013.

[2] IPC-4101C: Specification for Base Materials for Rigid and Multilayer Boards

[3] Geert Willems, Piet Watté, Predicting PCB delamination in lead-free assembly, Global SMT &
Packaging, Vol. 10, No. 9, September 2010, p. 10.

Situation today!

  • We live in the lead-free soldering era
  • Soldering temperatures are higher than before (+25-35°C)
  • Five years experience with lead-free soldering of FR-4 boards has revealed advantages and disadvantages
  • The quality and reliability of your product is critical for its success in the market-place
  • These factors make the choice of PCB laminate base materials increasingly important
  • But how do you as a PCB designer make an informed choice?
  • And how can you design robustness into your PCB to ensure optimum quality during assembly and reliability during the whole envisaged product lifetime?

First reaction!

There are a host of material parameters to consider for the current generation of PCB designs:

  • T260, T288
  • CTEz
  • Td
  • Tg
  • Moisture absorption

They determine whether or not your PCB will delaminate and the vias will survive the lead-free assembly conditions applied to your PCB.

How do you select the right combination for your design?

One could select the best possible value for each parameter but this limits the number of available materials considerably. Furthermore, these materials have their own disadvantages such as a poor manufacturability and brittleness.

What are the consequences? Is your problem solved?

  • If you select non-standard materials with unnecessarily high thermal performance requirements a way too expensive PCB is the result.
  • Your board supplier may not stock the material you have specified.
  • The material manufacturer may cease production of less frequently used materials.

=> Your PCB supply is expensive and not future safe.


To provide a cost effective and scientifically sound solution to its customers Eurocircuits partnered with imec’s Center for Electronics Design & Manufacturing. The methodology presented here is described in detail in PBA Design-for-Manufacturing Guideline: EDM-D-001: PCB Specification, developed by imec/cEDM and available at Parts of the guideline are reproduced here with permission of imec/cEDM.

Better start from what you know and can control!

Your product will be soldered lead-free so you need lead-free soldering compatible FR-4. The requirements for the PCB laminate depend on:

  1. How many times your PCB will be raised to lead-free soldering temperature during fabrication and assembly or “how many soldering cycles will your board need for assembly and possible repair?”.
  2. The maximum operating temperature for your application.
  3. The planned lifetime of your application counted in number of thermal cycles.

Your internal or external assembly partners should be able to provide the answer to the first question. Your customer or the end-user is the source to find the answer to the other questions.

Possible fabrication and assembly soldering cycles

How to determine the number of soldering temperature cycles to a PCB? The answer is given in the table below, Ref. [1].

The PCB fabrication and assembly processes given in the first column determine the number of solder cycles to be taken into account.

Process Cycles Explanation
HAL lead-free (bare board) 2 One HAL dip + one extra dip
Reflow 1
Wave soldering 1
Selective soldering 1 Including manual soldering
Touch-up / repair 1 Removing shorts or opens on leaded components
Component replacement 3 Removal+clean+re-solder: valid for using local heating

Specifications of lead-free soldering compatible FR-4

Always start from an internationally accepted standard. The IPC standard that defines lead-free solderable FR-4 is IPC-4101C:

  • There are 14 classes of lead-free compatible laminates: /99, /101, /102,/103[WG1] ,/121,/122, /124, /125/126,/127,/128,/129,/130,/131, each with slightly different properties.

More detailed information can be obtained via

  • Key parameters:
    • Decomposition temperature: Td (Thermal decomposition temperature: see further)
    • Time-to-delamination: T260, T288, T300 (Time to delamination at 260°C, 288°C and 300°C; see further down)
    • Z-expansion (thickness direction): coefficients of thermal expansion alpha 1 and alpha 2 (ppm/oC), and CTEz the z-expansion in % between 50oC and 260oC

Rather than specifying a base material to your PCB supplier, check that his materials conform to one of the IPC defined classes and see what minimum values he guarantees for these key parameters. Your boards will be cheaper and available faster.

Let”s compare the SnPb era FR-4 against the lead-free compatible FR-4 in respect of these key parameters.

Typical values of SnPb-era FR4 laminate materials compared to those of the lead-free compatible FR4 classes .

FR4 SnPb













Td (°C)














T260 (min)














T280 (min)

>10 sec













CTEz (%)














As the table shows, there are significant differences between older FR4 and current lead-free solderable FR4s (shown in IPC classes) for the key parameters Td, T260, T288 and CTEz.

We now solder 25-35°C hotter than in tin-lead solder times. This causes risks for:

  • Delamination: parameters T260, T288 and to a lesser extent Td.
  • Via cracks: parameter CTEz

Let”s further examine the effect of these parameters.


  • Driving force:
    • Laminate decomposition
    • Moisture within the PCB[1]
  • Key parameters:
    • Time-to-delamination: T260 – T288 – T300
    • Decomposition temperature Td
  • Failure types
    • “blisters”
    • High Ohm resistance shorts
    • Track failure (open circuit)
    • Via cracking (open circuit)
    • Field failure (usually not detectable during PCB assembly testing).



Delamination (extended separation inside the PCB)

Not more than 25 % of the distance between adjacent conductors or plated-through holes.

Not more than 1% of the printed wiring area on each side may be affected.

No propagation as a result of thermal stress testing or representative condition.


(6A) shows separation between two glass weave layers in the base material. The separation can also occur between the base material and the copper foil.

shows a separation between individual layers.

and (6D) show separations between laminate and internal or external pads respectively, or copper planes.



Key specifications of FR-4 with respect to temperature behavior

  • Decomposition temperature – Td
    • Measured using TGA: Thermo-Gravimetrical Analysis
    • The decomposition temperature Td determines how fast your board starts to degrade during heating. On reaching the Td temperature after heating up at a speed of 10°C/min, 5% of the base material will be decomposed. Since lead-free soldering needs temperatures about 25°C hotter than before, we need Td values for our material that are higher than before.
  • Time-to-Delamination: T260-T288-T300
    • Measured using TMA: Thermo-Mechanical Analysis
      T260-T288-T300 determine how long your base material can resist these temperatures before the material starts to delaminate (the material will increase in thickness).

Cycles to delamination as a function of laminate properties

Research and modeling by imec-cEDM has proven, Ref. [1, 2], that the IPC /sheet boundary conditions – especially the fixed T260≥30min does not provide sufficient protection to delamination. The following IPC-4101 compatible definition of thermal performance classes guarantees the indicated number Nd of solder cycles without cohesive[2] delamination, Ref. [1]. Note the more stringent T260 and T288 requirements.



Td (°C)

Min. v

T260 (min)

Min. v

T288 (min)

Min. v

CTEz (%)

Max. v


Potentially compliant

IPC-4101 sheet numbers







99, 101, 102, 103, 121, 122, 124,

125, 126, 127, 128, 129, 130, 131







99, 102, 103, 124, 125, 126, 128,

129, 130, 131







102, 126, 130


A mid performance material with a T260≥50min and a T288≥10min will be able to withstand at least 12 solder cycles before delamination will occur in the bulk of the laminate assuming the PCB is dry. The physico-chemical mechanism links Td, T260 and T288. Therefore, the actual Td value is not an additional parameter.

Graphs to determine the number of solder cycles to delamination for a given combination of Time-to-delamination and decomposition temperatures are given respectively in EDM-D-001 and Ref. [2]. A calculation tool is available at (free use for cEDM members).

Via cracking

A via crack is usually caused by the difference in thermal expansion between the laminate and the copper barrel of the hole. This is influenced by the thickness of the board, the thickness of the copper plating and the diameter of the hole. The key material parameters for this is the CTEz value.

  • Driving force:
    • Difference in CTE between the laminate and the copper plating of the via.
  • Key parameter:
    • CTEz: 50-260oC. The higher the expansion the worse the situation is.
  • (Tg, α1, α2) (Explanation further down in the text)
  • Failure types
    • Apparently open solder joint (especially BGA)
    • Intermittent open connection
    • Open via connection
    • Field failure (often not testable during manufacture)
    • Reduced PCB lifetime


Via cracks due to thermal stress can appear during soldering or during the operation of the board. Soldering stress cracks are tested by repeated soldering and for operational lifetime one tests this effect through accelerated thermal cycling testing (typical -40oC/125oC).

Let’s concentrate on the most critical effect of temperature cycling: z-axis tension in the via barrel due to the much larger Coefficient of Thermal Expansion CTE of the laminate in the z-axis compared to the CTE=17ppm/oC of copper.

CTEz, α1, α2: expansion in z-direction




The material parameter that has the biggest impact on cyclic tension in the z-axis direction is the CTEz value.

In the graph above you can see the relationship between the z-axis expansion of the material (CTEz) and temperature. The expansion is a rather linear process but has a click point where the angle of the curve changes and the z-axis expansion increases faster per °C. This click point is at the Tg value of the base material. It is actually the way the Tg is determined using Thermo-Mechanical Analysis (TMA).

The graph also shows that a traditional FR-4 material with Tg=150°C (orange line) has a CTEz value which is a lot higher than for the new lead-free solderable material (light green line) with the same Tg value. This is achieved by reducing the CTE of the laminate through the use of inert fillers (increases drill wear!) or/and using higher functionality epoxy types (harder, more brittle materials).

Conclusion: CTEz is far more important than Tg with respect to z-axis expansion. A higher Tg material does not guarantee a higher thermal performance with respect to lead-free soldering. However, it will increase the PCB cost.



Via crack model

According to EDM-D-001, 4.4.3, Ref. [1], plastic via deformation dominates under soldering conditions. Therefore, the via lifetime (number of solder cycles to failure) depends mainly on the CTEz value of the laminate. The small dependency on the via dimensions can be neglected for specification purposes. EDM-D-001 provides CTEz based criteria for selecting laminates that will provide sufficient number of solder cycles to via failure.

Eurocircuits materials with a maximum CTEz=3.5% guarantee conservatively less than 1% via failure after 14 solder cycles.

Note that under soldering conditions the vias are stretched by several percent which is a very large mechanical load knowing that via barrels will immediately fail when stretched by 7 to 10%, Ref. [1], Appendix B.

Via: operational reliability – number of -40/125oC cycles to via-failure

Under operational conditions the dimensions, board thickness and plating thickness may have a significant impact on the lifetime. In general the stress increases and thus the lifetime decreases with increasing board thickness, decreasing via diameter and decreasing plating thickness. Imec/cEDM developed an accurate analytical model to calculate the via strain during thermal cycling and to estimate the via lifetime.

The graphs below show the dependency of the via strain under -40/125oC cycling for a laminate with a1=50ppm/oC, an board thickness D and via diameter d for t=20μm (left) and t=10μm (right) via plating. (FEM: numerical Finite Element Modeling results)


Using the Wöhler relationship which relates the number of cycles to failure to the cyclic strain on the vias the lifetime of the vias under different operational conditions can be calculated. An online via lifetime calculation tool is available at (free for cEDM members). An offline version for embedding in PCB design tools is available from imec/cEDM.

Impact of soldering on the life expectancy of the PCB: via degradation

As mentioned before soldering imposes very large stresses on the vias. When the via does not fail during soldering – which is off course the intention – the lifetime of the PCB vias is reduced after soldering compared to the lifetime of vias of an unsoldered board. EDM-D-001 explains how this effect can be calculated. Again, selecting materials with a low CTEz reduces the impact of the soldering on the via lifetime.

If we look again at our standard value CTEz of 3.5% we achieve less than 4.6% loss of life expectancy per applied solder cycle, EDM-D-001, 4.4.4, leading to an overall lifetime reduction for an unrepaired PBA between 13 to 20%.

Eurocircuits pooling panels.

The vast majority of our orders are produced on pooling panels.

The standard technological values for these boards are:

– board thickness 1.6mm

– minimum track & gap 150µm

– smallest hole size 0.25mm

– minimum copper plating in the holes 20µm


Based on these values and imec/cEDM’s methodology described in Ref. [1] and explained above, we have determined specifications for the base material we use.


Our goal is to offer our customers a guaranteed performance for our PCBs during their assembly processes and sufficient PCB reliability for medium operationally stressed electronic assemblies.

How often may you heat up your PCB to soldering temperature?

  • Pooling – minimum material specifications and maximum number of solder cycles
    • T260 = 60min, T288 > 10min & Td = 325°C =>16 cycles
    • CTEz = 3.5%
    • 1.6mm PCB => 14 cycles 1% failure or 11 cycles 0.1% failure
    • 20µm plating
    • Tg 145°C=> max operating temp 120°C
    • Eurocircuits wants to be on the safe side => -2 cycles
    • Lead-free hot-air solder-leveling involves => -2 cycles
  • So, using our minimum guaranteed material specification, a standard Eurocircuits pooling PCB with lead-free HAL finish may be raised to the lead-free soldering temperature (=<260°C) during assembly 10 times – on condition that the PCB is sufficiently dry[3].
  • The PCBs maximum operational temperature is 120°C.
  • In fact, the materials we currently use, Isola IS400 and Nan Ya NP-155F, perform much better than our minimum guaranteed specifications. They have the values: T260=60 minutes, T288>10 minutes, Td=350°C, CTEz=3%, Tg=145°C. CTEz=3% would bring the basic number of solder cycles already to 20 with 1% failure instead of 14 cycles.
  • Via reliability decreases over time and with every applied solder cycle (for example, 8 cycles at 4.6% adds up to +/-37% loss of life expectancy).
  • For better reliability use large vias and limit board thickness. The laminate CTEz and the CTE below Tg a1 are the dominating via reliability parameters.

“hot” – “hotter” – “hottest”

Like any good steak, any good PCB can be burned!

This article is made with the support of:

Imec’s Center for Electronics Design & Manufacturing
Kapeldreef 75
3001 Heverlee

Geert Willems – 0498 919464 –



[1] Moisture absorbed into the PCB can exacerbate delamination and, due to the higher soldering temperature, has become a much more critical parameter than it was with SnPb solder. It can be countered by storing PCBs in a temperature and humidity controlled environment. As moisture, if present, would be a local variable, we have not considered it further in our discussion of material properties.

[2] Cohesive delamination: delamination in the bulk of the laminate as opposed to delamination at the resin/copper interface.

[3] Moisture absorbed into the PCB increases the tendency to delamination due to the additional internal stress of the water vapor pressure. This can be countered by storing PCBs in dry bags or low humidity (<5 RH%) dry cabinets.

Pilot the eC-reflow-mate

How to pilot the eC-reflow-mate?

Watch the program on the eC-reflow-pilot:

program ec pilot


  • On the left hand side we see that the bottom heater is set to follow the top heater with a difference of -40°C. So a top heater reading of 200°C would steer the bottom heater to 160°C. (more about pre-heater).
  • The reflow TAL time is set to 15 seconds. This means that when reaching the highest temperature point in the curve, the oven controller will keep that temperature for at least 15 seconds. When this function is set, the oven will heat until the highest temperature is reached, regardless in which time frame. It will hold the temperature for 15 seconds in this case and then jump back to that highest point in the curve and continue the rest of the curve. (see also eC-reflow-mate hold time and eC-reflow pilot hold time).
  • The curve itself looks unsmooth and when performing a solder test we can see that the temperature shown in the temperature scope in the bottom part of the screen, does not follow the theoretical curve at all. What is happening?

Controlling the oven is like driving a car.

heating up
  • The first step we step in our curve is jump to 100°C in a few seconds. That is not going to happen. It”s like pushing the gas lever of your car when the traffic light turns green. The car is not jumping from 0Km/H to 70Km/H in 0 seconds flat. It needs time to accelerate. The oven reacts in the same way. Telling the oven to heat up, will launch a current through the Infrared lamps. This current will heat up the lamp wire which then will start to heat up the oven and the board. It will take some time.
  • The second section of the curve reflects a slow acceleration. After you have told your car to accelerate, you release somewhat the gas lever, giving your car time to accelerate slowly to the 70Km/H desired. The same you do with the oven.
  • Whenever the oven reaches the highest point of the curve depends on the type of board you are soldering. Heavy copper boards will require more time. Time is exactly the only parameter to manipulate the curve: “time”. When you do not know how a board is going to react, it is best to solder it using the external sensor and thus measuring the temperature on board and using the reflow TAL function, explained above to guarantee that you reach the reflow temperature.

Cool down, open the door.


door open
  • The next point is the door open point. The temperature will never drop like we define in the theoretical curve. What we set is “hit the brakes” like we do with our car when we see a red traffic light. Only in case of the oven it means that we stop heating. From that point on the oven will cool down very slowly as he is very well insulated. From the moment that the temperature reaches the temperature set in the door open point, the door will open. The door open point is temperature controlled and not time controlled as we need to be below solder temperature before we open the door thus no components will move anymore.

No hidden tricks during the Eurocircuits PCB soldering workshops – all demonstrated materials are available in our shop

Eurocircuits is organising workshops on PCB prototype assembly and soldering.

These workshops are presented by Ben Verwaest from ARCOSS and Uwe Dörr from Eurocircuits. We refer to earlier blog articles to get an impression of what is happening during these workshops.

Ben is an expert in the field of PCB assembly. He is frequently consulted by professional assembly houses for process trouble shooting.

The materials we use during the workshop sessions are selected by Ben for their quality and performance. Together with ARCOSS, Eurocircuits now offers these products in small quantities, fitting the need of electronics engineers to assemble their prototypes.

Some examples:

Solderpaste has a short shelf life, so we pack it in small 140 gr jars, more about the advantages and specifications you can find here .



To clean your stencils and printing material, we offer eC-stencil-wipes and eC-wipes.



We trust you will appreciate the quality of these products to achieve the same professional PCB soldering result as we show during our Eurocircuits workshops.

Eurocircuits serving the engineering community

An assembly solution for the wider electronics engineering community

At Eurocircuits we are already well-known for our powerful offer manufacturing prototype and small batch PCBs for electronics engineers.  We have already extended this back into the design process with our links to EAGLE and to Altium.  But what about assembly?

We are often asked if we can assemble boards and several of our competitors offer this service.  The following diagram illustrates powerfully why we should not.

prototype assembly market


Prototype and small batch assembly requires a heavy investment in equipment and expertise.  So it has a high cost of service.  On the other hand, customers are driven by price.  The value of the service is perceived solely in price terms, cutting prices and lowering margins.  The pure prototype assembler risks getting caught in the mouse-trap where low prices mean that he can no longer cover the cost of his service.  Two ways of increasing margins have emerged over over the last few years.  Some assembly companies have stayed with small batch assembly but moved into very high technology markets like defence, aviation, medical or high-end communications.  Others have moved into high-volume assembly, only making prototypes as a loss leader to land large contracts.

At Eurocircuits we have evolved our business model to handle medium technology prototype and small batch PCBs quickly, reliably and cost-effectively.  We are not in the very high technology market nor are we volume producers.  So offering a “me too” prototype assembly service would not work.  And in any case it doesn’t make business sense to compete with our customers.

We have a better solution.

When he needs prototype and small batch assembly, the customer’s service perception is highest when his needs are met immediately.  For a designer this may be difficult to achieve using a sub-contract company.  He has to spend time communicating his requirements and he has to wait for a slot in the sub-contractor’s scheduling.  On the other hand, if he does his own assembly there is no delay.  He knows what the design has to do; he knows the components; he can start as soon as he is ready.  Of course he needs a supply of components, he needs suitable equipment and he needs to know how to use it.  Our eC-solutions program means that we can offer our designer customers a full range of suitable equipment and back it up with training programs and consumable supplies, developed in-house and via our partner companies.  For more information on the program, go to our website section about smd-reflow-soldering equipment

eC-workshop report – reflow soldering SMD PCB prototypes- Belgium 22-03-2012

Overview of our first seminar 22-03-2012 and dates for future seminars.

We started with a warm welcome and the registration of our participants accompanied by a cup of coffee. 19 out of 20 preregistered participants found their way to ARCOSS for our first seminar on reflow soldering of SMD PCB prototypes.


arcoss office Retie welcome


Dirk Stans spoke a word of welcome and gave an overview of the planning for the day. Dirk continued with the Eurocircuits history for the last 20 years followed by a brief overview of Eurocircuits services.

Eurocircuits history


The introduction of the eC-prototype-equipment was the next item on the agenda. Here Dirk explained why Eurocircuits have entered into this venture and explained the two machines eC-stencil-mate and eC-reflow-mate and their specification in detail. Special focus was laid on the difference between reflow chamber soldering and its solder curves and reflow soldering in a throughput oven.



Next Ben Verwaest, MD of ARCOSS, explained the process of reflow soldering with all its phases in great detail, accompanying his exposé with many practical tips and do”s and don”ts.

Ben teaching Ben teaching


Ben also explained the correct use of the screen printing process and the materials and consumables to be used. This led into an explantion of the specially developed eC-kits of consumables and tools for every function in the process: eC-stencil-mate-kit, eC-reflow-mate-kit, eC-equipment-starter-kit and the eC-ESD-kit.

eC-kits ben teaching


Lunch time. The company ARCOSS pleased the group with a nice sandwich lunch.  As the weather Gods were favoring us with some nice sunny skies, we could enjoy it all outside on the terrace.

After lunch, it was Uwe”s turn. Uwe Dörr, our application specialist for the eC-equipment and project manager for the development of the eC-equipment, demonstrated the screen printing with the eC-stencil-mate.

uwe -ec stencil mate uwe fixing stencil


Ben then showed the quality of the printing under a microscope and proved that he still possesses a pair of skilled hands by mounting the components with tweezers.

eC-solderpaste printed mounting components


Some customers participated in the population of boards as we made more than one. After that only the reflow soldering with the eC-reflow-mate remained to achieve a finished assembled prototype board. This went smoothly convincing all of the soldering qualities of the eC-reflow-mate.

All materials used during the workshop are available from Eurocircuits :

– Spare parts and starter kits

– eC-solder paste (140 gr)

– eC-stencil wipes and eC-wipes




The next part was dedicated to the practical skills of the ARCOSS team.

Hand soldering of a fine pitch PQFP-208 pins gull wing component made quite an impression on the participants. The ease with which Ben Verwaest soldered this component to the board with a mini wave soldertip left an impression and convinced people this was not rocket science but something of which one should learn the practical tricks and then start doing it. In the second part, the BGA soldering of individual components, ARCOSS application engineer Sven played the main role. Sven used the PACE solder and rework BGA/QFN station to perform the job.

 placing BGA



bga mount.jpg bga mounted.jpg


All was inspected with the companies X-ray machine, which by itself made a good demonstration of what is possible with that technique. All together it proved to be a useful day which brought us many positive and useful feedbacks.

This positive feeling and the fact that we already had more candidates for attending the seminar than we had available places led us to decide to repeat this seminar another 3 times. The dates we planned for this are the 15th, 22nd and 23rd of May. Registering for any of these days can be done using the registration link below which will open a registration page and form. Please fill in your details and the day of your choice. Please use the form to register as it will help to smooth the process and keep an overview of who registered when. The places for each day are limited to 20 and are assigned on a first come first served basis. The limit of 20 participants is of a practical nature and helps us to keep the quality of interaction with the audience high.

Update 10/05/2012 : There are no places available anymore for the seminars on May 15, 22 and 23. We will keep you informed about future seminars we organise

eC-workshop – reflow soldering SMD PCB prototypes

eC-workshop – Belgium  March 22, 2012

Eurocircuits are organizing a workshop on using the eC-reflow-equipment for the reflow soldering of SMD PCB prototypes.

Already 160 Eurocircuits customers throughout Europe are using our eC-reflow-equipment, the eC-stencil-mate and the eC-reflow-mate. Let us convince you of the ease of use, the quality and the reliability of our equipment at a dedicated hands-on workshop on SMD reflow soldering using our equipment.

The workshop is free. It will take place at 10:30 on 22nd March, hosted by our reflow soldering partner “ARCOSS” at Looiend 60 – 2470 Retie -Belgium

Specialists from Eurocircuits and ARCOSS on the eC-reflow-equipment and SMD reflow soldering will be on hand to demonstrate the equipment and to answer all your questions on the reflow soldering of surface-mounted devices.

Registration for the workshop will close on 15 March or earlier if the maximum number of attendees is reached before this date. In this case we will arrange a second workshop on a later date.

More detailed information on our eC-reflow -equipment can be viewed here.

Hand-soldering – point by point or mini-wave technique

Hand-soldering with the same high quality result as reflow or wave soldering?

Are you ready for the challenge ? Let us look at  the mini-wave soldering technique.


perfect tools?

 This picture shows that tools and skills are the basics to achieve a good result in hand-soldering. You agree ?

Hand-soldering is in most cases the last step in the prototype assembly process. Why is it less controlled and more difficult than other steps in the manufacturing. It is something we all know how to do. It”s just heating up a PCB and a component to make a solder joint. Isn”t that simple?

PCB designers, technicians, electronics engineers, we all learned at school how to solder with an iron. It can be 5 or 35 years ago, but we assume that not a lot has changed. A lot did change!

Do we still take our car to a service where they have only mechanical hand-tools to fix it ? They do have a lot of tools these days to do a good repair job.





Soldering connections – Solderjoint

A good solderjoint is an electrical and mechanical connection which in the best condition is made in one shot with a temperature as low as possible, and as quick as possible. This rule is still valid, even when solder-alloys have changed from Sn63/Pb37 to the leadfree SAC305, SN100,.. or whatever the alloy used.

A good iron and the right skills makes the perfect start. What is the temperature of your iron today? How is the geometry and condition of your tip? What solder-materials do you use? Are you soldering leadfee assemblies?


 Today we show you a technique to solder a SOIC-16 (Small outline Integrated Circuit 16 I/O) or PQFP-100 with Gull Wing leads. The quality we like to match is the same or even better than in a full automated production line. We all know how to solder this point by point, but do we master the Mini-wave technique?










See more details from the SOIC in the package outline

PQFP component SOIC 16




What do we need :

  • Soldering station (iron)
  • Soldertip
  • Solderwire
  • Flux past / Flux pen
  • Tweezer
  • Cleaning product
  • EPA zone ( ESD protected area)

How do we proceed:

  • 1. Set the temperature as low as possible considering the pcb design ( layers, copper mass )
  • 2. Insert the tip into the soldering iron
  • 3. Heat-up the tip and check the tip conditions: the solder should flow (spread evenly) over the plated tip area.
    • If this is not the case, clean the tip surface ( to remove oxidation)
    • if this does not help, replace the tip with a new one.
  • 4. Place the SOIC 16 on the PCB and attach 2 or 4 corners to hold the component in place ( Apply flux to the pads before placing the SOIC on the board)
  • 5. Add flux paste or flux to all leads/pads on the SOIC16
  • 6. Clean the solder-tip on a wet sponge or brass tip cleaner
  • 7. Add solder to the tip-end (miniwave or conical tip)
    • Point by point soldering:

      • Solder all leads individually – point by point by adding the right amount of solder. The solder is provided by hand using a fine solderwire.
    • Mini-wave soldering:

      • Place the mini-wave tip ( parallel to the pads) on the first pin of the PQFP/SOIC and move along the pins at a constant speed. Solder all leads in less then 5-10 seconds.
      • Do the same thing again on the other sides of the PQFP/SOIC
  • 8. Clean all Flux-residues with a cleaning solvent and ESD-safe trigger grip
  • 9.Check all solderjoints/connections with a microscope/videomicroscope/magnifier.
Inspect joints


The difference between both techniques is that the point to point technique takes much more time than the mini-wave technique. With the point to point technique it is also more difficult to have an even quantity of solder on all the joints.

eC-Workshop: Prototypen perfekt SMD-Bestücken (Germany)

Mehr als 150 Kunden kauften bereits das eC-reflow-equipment von Eurocircuits.

überzeugen auch Sie sich in einem Workshop von der Qualität, Einfachheit und Zuverlässigkeit unserer professionellen Lösung zur Prototypen-Bestückung.

ec-reflow-mate ec-stencil-mate


Der erste Workshop findet am 23.02.2012 um 10:30 in 41812 Erkelenz stattBei Bedarf werden wir weitere lokale Workshops organisieren.

Da die Teilnehmerzahl für die kostenlose Vorführung begrenzt ist, bitten wir Sie bei Interesse für einen Workshop das zutreffende Formular auszufüllen

Hier erhalten Sie Informationen zu unserem eC-reflow-equipment:

Allgemeine Informationen zum eC-reflow-equipment

Informationen zu eC-stencil-mate

Informationen zum eC-reflow-mate

Informationen zu eC-reflow-pilot


We plan to organise eC-Workshops on PCB prototype assembly in other countries also in the future. When you want to be informed when there is a workshop in your area, pre-register here and we will keep you updated.

Visit our calendar to see all upcoming events