Report. Soldering Tests at COM Express Connectors, Type Receptacle and Plug. Order: Bergwerkstraße 50 D Peiting. Your Order-No.

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1 Zentrum für Verbindungstechnik in der Elektronik Argelsrieder Feld Oberpfaffenhofen-Weßling Telefon: / Telefax: / Report Order: Soldering Tests at COM Express Connectors, Type Receptacle and Plug Customer: ept GmbH Bergwerkstraße 50 D Peiting Your Order-No.: ZVE Order No.: Report Size: Editor: 13 pages Dr. S. Wege Date:

2 Soldering Tests at COM Express connectors, type Receptacle and Plug Summary For the investigation two types of COM Express connectors (Receptacle and Plug) exist. The solderability of the pins should be controlled using a reflow soldering process. The conclusion of all results is that the two types of the connectors show a good soldering behavior and the formation of the solder joints is in accordance with the criteria of the IPC A 610 standard, also for class Investigations For the investigation two types of SMD connectors (COM Express, Receptacle and Plug) exist. The solderability of the pins should be controlled using a reflow soldering process. Additionally comparable soldering tests with two similar types of SMD connectors, produced by Tyco, were made. Also connectors which were soldered by ept, using a small version of a reflow oven, were available. The quality of the solder joints of all variations should be assessed and compared, considering the criteria of the IPC A 610 standard. For the soldering tests the testboards were supplied by ept. A standard leadfree solder paste with the composition SAC 305, type 4 was used. The printing of the solder paste was made with a manual equipment of ept. The placement of the connectors was also manually. For the soldering tests a SMT reflow machine and a standard leadfree profile with a peak temperature of 245 C were used. The results of soldering tests were optically inspected. Additionally at some specimens an X- ray inspection was made to check the uniformity of the solder formation at all pins of the connectors and to control the porosity in the solder gap between the printed circuit board and the pin. Figure 1: overview of the test boards with the soldered connectors page 1

3 Results The results of the optical inspection for the connectors of ept are shown in the figures 2 7. The pins of the connector type Receptacle are completely wetted and an acceptable solder fillet in the bend of the pin was formed. The solder doesn t reach the package of the connector. Therefore the solder joints fulfill the acceptability criteria of the IPC A 610 standard. The pins of the connector type Plug are gold-plated and have a larger thickness. The pins are also completely wetted. The height of the solder fillet in the bend is about 50 % of the thickness of the pin. Figure 2: connector type Receptacle (ept) optical inspection of the soldered pins Figure 3: connector type Receptacle (ept) optical inspection of the soldered pins page 2

4 Figure 4: connector type Receptacle (ept) formation of the solder joints at the side of the pins Figure 5: connector type Plug (ept) optical inspection of the soldered pins Figure 6: connector type Plug (ept) optical inspection of the soldered pins page 3

5 Figure 7: connector type Plug (ept) formation of the solder joints at the side of the pins The solder joints of the Tyco connectors (Figure 8 and 9) with a similar type show a comparable appearance to the results for the connectors of ept. At the connectors, type plug, the surface of the solder joints looked more homogeneous, because the pins were tin-coated. At this component the height of the solder fillet in the bend is also only about 50 % of the thickness of the pin. Figure 8: connector type Receptacle (Tyco) optical inspection of the solder joints Figure 9: connector type Plug (Tyco) optical inspection of the soldered pins page 4

6 The results of the X-ray inspection are demonstrated in the figures It can be seen that at all researched variations the solder joints are homogeneous formed about the whole length of the pin and the porosity in the solder joint directly under the pin is small. Figure10: X-ray analysis - soldered connector type Plug (ept) soldering tests (ept) Figure11: X-ray analysis - soldered connector type Plug (ept) soldering tests (ZVE) page 5

7 Figure12: X-ray analysis - soldered connector type Receptacle (ept) soldering tests (ZVE) Figure13: X-ray analysis - soldered connector type Receptacle (ept) soldering tests (ZVE) page 6

8 Figure14: X-ray analysis - soldered connector type Receptacle (Tyco) soldering tests (ZVE) Figure15: X-ray analysis - soldered connector type Receptacle (Tyco) soldering tests (ZVE) page 7

9 Figure16: X-ray analysis - soldered connector type Plug (Tyco) soldering tests (ZVE) Figure17: X-ray analysis - soldered connector type Plug (Tyco) soldering tests (ZVE) page 8

10 Figure18: X-ray analysis - soldered connector type Plug (Tyco) - serial assembly To examinate the formation of the solder joints exactly additionally a metallographic cross section through two soldered pins of the two connector types (figure 19) was made. The results are demonstrated in figure In both cases the whole length, the heel of the pins is completely wetted and the solder doesn t touch the body of the component. The solder height at the top of the pin is not defined. Therefore the solder joints fulfill the criteria of the IPC A 610 standard, also for class 3. For the assessment of the solder joints the criteria for flat ribbon and gull wing leads were used, because the connector pins have a special shape, which is not described in the IPC A 610 standard. In this case for class 3 applications the acceptance criteria should be adjusted with the customer. Figure19: over view of the connectors, chosen for the metallographic examination left: type Receptacle, right: type Plug page 9

11 Figure 20: overview of the solder joints of connector type Receptacle Figure 21: metallographic cross section through the solder joints of connector type Receptacle overview page 10

12 Figure 22: metallographic cross section through the solder joints of connector type Receptacle detailed view of figure 21 Figure 23: metallographic cross section through the solder joints of connector type Receptacle detailed view of figure 22 Figure 24: connector type Receptacle formation of the solder joints at the boundary of the pin and the PCB page 11

13 Figure 25: overview of the solder joints of connector type Plug Figure 26: metallographic cross section through the solder joints of connector type Plug overview page 12

14 Figure 27: metallographic cross section through the solder joints of connector type Plug detailed view of figure 26 Figure 28: metallographic cross section through the solder joints of connector type Plug detailed view of figure 27 Figure 29: connector type Plug formation of the solder joints at the boundary of the pin and the PCB page 13