Pin-in-Paste Reflow Calculations and Special Cases
The major concern of the pin-in-paste reflow process is the quality of the solder joint. It must meet IPC610 standard. The criteria for IPC610, class 2 are:
To meet the above requirements, the following steps need to be considered:
Both sides of the wire leads must obtain at least a 75% solder coverage
Air cavities should be less than 30%
The surface of the drilling as well as the component’s lead must have 100% wetting.
Solder alloy volume calculation
The volume between the hole and pin (Vsolder >= V hole + V fillet – V pin) should be filled up by the solder alloy with good fillet.
Minimum applied paste volume calculation
Solder paste contains about 50% of metal material and 50% additional material (flux) which oozes out during the reflow process. So the minimum paste volume requirement is:
V paste = 2 x Vsolder = 2 x (Vhole + V fillet – Vpin)
Stencil aperture oversize design
The area of the aperture is calculated as follows:
Apaste = Vpaste / Stencil (where the Stencil = the stencil thickness.)
The Stencil aperture size is calculated as follows:
If it is a circle, then the Dstencil = 2 x SQRT(Apaste / ? ) , where Dstencil is aperture diameter.
If it is square, then the Lstencil = SQRT(Apaste ), where the Lstencil is the aperture length.
If it is rectangle, then Apaste = Lstencil x Wstencil, where the Lstencil is the aperture length and Wstencil is its width.
In most of situations, the aperture size will be bigger than pad’s size. This means that the solder paste will cover or extend over the entire hole.
Double Stroke: Special Paste Printing
To get enough paste into the hole, double stroke is an acceptable process when the right pressure is applied. The squeegee print speed should be adjusted at a slower rate to let the paste fill the apertures more completely. This causes more solder paste to be deposited.
SMT Reflow Oven, Lead free Reflow Oven, Reflow Oven Manufacturer, LED reflow oven, PCB Reflow Oven, Nitrogen Reflow Oven, Dual Rail Reflow Oven, China Reflow Oven, wave soldering machine, Dual Rail Wave Soldering Machine, Nitrogen Wave Soldering Machine, Wave Soldering Machine Manufacturer.
|Flason Electronic Co.,ltd provide a full SMT assembly line solutions, including
SMT Reflow Oven,
Wave Soldering Machine,
Pick and Place Machine,
SMT Stencil Printer,
SMT AOI SPI Machine,
SMT Reflow Oven,
SMT Peripheral Equipment,
SMT Assembly line,
SMT Spare Parts
etc any kind SMT machines you may need, please contact us for more information:
wechat whatsapp:+8613691605420, Skype: flasonsmt, Email: email@example.com||FAQ|
1) This is the first time I use this kind of machine, is it easy to operate?
There is English manual or guide video that show you how to use machine.
If you still have any question, please contact us by e-mail / skype/ phone /trademanager online service.
2) If machine have any problem after I receive it, how can I do ?
Free parts send to you in machine warranty period.
If the part is less than 0.5KG, we pay the postage.
If it exceeds 0.5KG, you need to pay the postage.
3) MOQ ?
1 set machine, mixed order is also welcomed.
4) How can I buy this machine from you? ( Very easy and flexible !)
A. Consult us about this product on line or by e-mail.
B. Negotiate and confirm the final price , shipping , payment methods and other terms.
C. Send you the proforma invoice and confirm your order.
D. Make the payment according to the method put on proforma invoice.
E. We prepare for your order in terms of the proforma invoice after confirming your full payment.
And 100% quality check before shipping.
F.Send your order by air or by sea.
5)Why choose us ?
A. Gold supplier on Alibaba !
B. Trade assurance to US$54,000 !
C. Best price & Best shipping & Best service !