-
- News
- Books
Featured Books
- smt007 Magazine
Latest Issues
Current IssueBox Build
One trend is to add box build and final assembly to your product offering. In this issue, we explore the opportunities and risks of adding system assembly to your service portfolio.
IPC APEX EXPO 2024 Pre-show
This month’s issue devotes its pages to a comprehensive preview of the IPC APEX EXPO 2024 event. Whether your role is technical or business, if you're new-to-the-industry or seasoned veteran, you'll find value throughout this program.
Boost Your Sales
Every part of your business can be evaluated as a process, including your sales funnel. Optimizing your selling process requires a coordinated effort between marketing and sales. In this issue, industry experts in marketing and sales offer their best advice on how to boost your sales efforts.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - smt007 Magazine
Two Prevalent Rework Heating Methods--Which One is Best?
November 7, 2017 | Bob Wettermann, BEST Inc.Estimated reading time: 4 minutes
There are two prevalent heating technologies in use throughout most electronic assembly operations for advanced component rework. The first method employs the use of hot air gas to heat up the component through the package—this may or may not include the injection of nitrogen. A second much-used heating technology relies on infrared energy. This electromagnetic radiation, safe to the operators, is absorbed by the package, thereby sending the solder into reflow.
Hot Air Rework
A typical hot air rework system employs a heat source and an air source that forces the heated air through a nozzle (Figure 1) configured to the area of interest, which heats up the component to be reworked. There are numerous levels of such a hot air system, including a completely manual, a semi-automatic, and an automatic system, each with its own features.
Why Hot Air?
Hot air convection heating for PCB rework is advantageous for a variety of reasons. The absorption of heat by the component and circuit board is independent of a material’s color or texture. Additionally, inducing nitrogen to the site during component reflow has the advantage of making sure the metallurgical structure of the solder joint is the most reliable. In air-atmosphere rework, an oxide layer forms around the solder sphere as it reflows. Inducing nitrogen during this step displaces the oxygen and limits the oxide layer forming around the molten solder. Finally, a hot air convection system quickly delivers heat energy into thermally massive boards.
Figure 1: Nozzle delivers hot air in and around the package during rework cycle.
While there are many advantages to using a hot air rework system, there are some drawbacks the user needs to be aware of when trying to decide which reflow source to use. First, due to the nature of the hot air source and the ever-decreasing mass of SMT components, solder joints can be disturbed or parts can be skewed during reflow. This is especially true for 0201, μBGA and other micro packages. Secondly, to make sure the hot air blows effectively on the package and not onto the neighboring components, a customized nozzle is required. Too large a gap between the edge of the package and the nozzle and then the neighboring parts will tend to go in to reflow. A poorly-designed nozzle leaves a temperature gradient in the hot air source thereby leading to inconsistent results. In addition, customized nozzles take several weeks to fabricate and are not cost-effective for small quantities. Finally, in many cases the peak temperature will be higher for a hot air profile versus that of a similar IR reflow profile. This may cause parts in the neighboring vicinity to those being reworked to reach their softening point (like plastic-bodied relays and connectors), thereby causing damage to them.
What is IR?
Infrared (IR) technology, the other widely-used heating source for PCB rework, was first introduced into SMT repair equipment in the mid-1980s. An infrared heater is a body transferring energy to a body with a lower temperature through electromagnetic radiation in the infrared spectrum with wavelengths from 780 nm to 1 mm. There are two basic styles of IR technology. The first is medium range IR (Figure 2), which emits the energy and is “blocked” from some areas of the PCB by “shuttering.” The second is a focused IR heat source (Figure 3) in which IR radiation is collimated and directed through a lens system.
Advantage of IR
The IR heating source presents some advantages to the PCB rework process. It is important to realize how passive and gentle the method is and, in fact, at full power the heating effect is so slight that you can hold your hand in the beam for some considerable time before any effect is felt. This makes the technology advantageous for applications where heat-sensitive components found in rework may not be damaged.
Figure 2: Medium IR heating technology for PCB rework.
Page 1 of 2
Suggested Items
AIM to Highlight NC259FPA Ultrafine No Clean Solder Paste at SMTA Wisconsin Expo & Tech Forum
04/18/2024 | AIMAIM Solder, a leading global manufacturer of solder assembly materials for the electronics industry, is pleased to announce its participation in the upcoming SMTA Wisconsin Expo & Tech Forum taking place on May 7 at the Four Points by Sheraton | Milwaukee Airport, in Milwaukee, Wisconsin.
Hentec/RPS Publishes an Essential Guide to Selective Soldering Processing Tech Paper
04/17/2024 | Hentec Industries/RPS AutomationHentec Industries/RPS Automation, a leading manufacturer of selective soldering, lead tinning and solderability test equipment, announces that it has published a technical paper describing the critical process parameters that need to be optimized to ensure optimal results and guarantee the utmost in end-product quality.
Empowering Electronics Assembly: Introducing ALPHA Innolot MXE Alloy
04/16/2024 | MacDermid Alpha Electronics SolutionsIn the rapidly evolving electronics industry, where innovation drives progress, MacDermid Alpha Electronics Solutions is committed to setting a new standard. Today, we are pleased to introduce ALPHA Innolot MXE, a revolutionary alloy meticulously engineered to address the critical needs of enhanced reliability and performance in modern electronic assemblies.
New Book on Low-temperature Soldering Now Available
04/17/2024 | I-Connect007I-Connect007 is pleased to announce that The Printed Circuit Assembler’s Guide to… Low-temperature Soldering, Vol. 2, by subject matter experts at MacDermid Alpha Electronics Solutions, is now available for download.
Inkjet Solder Mask ‘Has Arrived’
04/10/2024 | Pete Starkey, I-Connect007I was delighted to be invited to attend an interactive webinar entitled “Solder Mask Coating Made Easy with Additive Manufacturing,” hosted by SUSS MicroTec Netherlands in Eindhoven. The webinar was introduced and moderated by André Bodegom, managing director at Adeon Technologies, and the speakers were Mariana Van Dam, senior product manager PCB imaging solutions at AGFA in Belgium; Ashley Steers, sales manager at Electra Polymers in the UK; and Dr. Luca Gautero, product manager at SUSS MicroTec Netherlands.